FMF 4.1 RCT Titanium Muffler With Mega Bomb Plus Headpipe


If you have kept up on my social media channels (@kkeefer120, @keeferinctesting) you will know that I have been riding the crap out of the 2018.5 Husqvarna FC450 Rockstar Edition and 2018.5 KTM 450 SX-F Factory Edition machines. I enjoy riding these two machines because they are easy to ride, well balanced and feel extremely lightweight when cornering. I do however wish they had some more RPM response and low-end excitement. Since the new Husqvarna RE’s and KTM FE’s are not coming with an aftermarket muffler this year I wanted to get my hands on FMF’s version as soon as possible to give you all some feedback, just in case you wanted to add some more bling and possible horsepower to your new machines.



The new FMF 4.1 RCT Full Titanium Muffler System that you see here will fit on either your 2018.5 KTM Factory Edition or your Husqvarna Rockstar Edition. The FMF 4.1 system went on easy on both bikes and took only a few minutes to install. Thank you to Husqvarna and KTM for making the new bike much easier to change a muffler. Gone are the days of dropping the shock and cursing in the garage just so you could get your new muffler system on. I tested the FMF 4.1 muffler system at several tracks on both bikes and had similar results at each track I tested at. In stock form the KTM Factory Edition has a little more throttle response and bottom end pull than the Husqvarna Rockstar Edition, but the RE pulls slightly longer up top. 



With the FMF system installed you will not be getting increased bottom end pull on either machine (compared to stock), but you will be getting a little more bottom and mid-range RPM response (or throttle crack for you not testing type readers). I noticed the added RPM response more on the Husqvarna, especially on low RPM, out of corners. The FMF system makes each machine’s engine character slightly more free-feeling and exciting. I also appreciate that I am not getting any added de-cel popping (or lean sensation) with the FMF system and both bikes ran just as clean with the FMF system on than it did with the stock muffler. Where you will notice the most improvement with the FMF system is through the mid-range. The mid-range “meat” you will get out of the FMF 4.1 system is downright impressive. Rolling the throttle on out of corners and accelerating you will notice an increased pulling power that wasn't there with the stock muffler on either machine. Whether you're coming out of a corner in second or third gear you will notice some extra horsepower getting to the next obstacle. With the added mid-range meat of the FMF system it really helped some of the gearing issues I had at tighter, less flowy tracks I tested at. Gaining some mid-range let me use third gear in some corners that was tough for me to decipher which gear was better. With the stock system I would roll into these corners in second gear and have the right amount of "pop" to get me out quick, but I had to shift early once exited, to keep the rear wheel from spinning. Third gear was too tall of a gear to get me out of the corner quick, but provided less wheel spin on the exit, so it was always a struggle for me to decide on which gear to use when being pressured from behind by another rider. With the FMF installed I could easily use third gear and have enough "pop" to get me out of the corner in a hurry, yet it kept the wheel spin to a minimum by being able to use a taller gear. So basically what I am saying is that FMF’s 4.1 system made me think less and twist the throttle harder, something I like doing. I didn't get any more top-end with the FMF installed, yet it didn't take any away from either machine. I did notice slightly less over-rev with the FMF system (from stock) when I got lazy and tried to wring each machine’s neck out in second and third gear. I don't mind not gaining anymore top- end and losing a touch of over-rev with these two models, because they are one of the most powerful engines in these ranges. I am not looking to own a top fuel dragster here. 



You have heard me say it time and time again that it's tough to beat a stock muffler system these days. You see more and more after market companies taking the time to release their new model systems because it’s not that simple to make a muffler system better than stock. FMF made their new 4.1 RCT titanium muffler with Mega Bomb Plus headpipe not only better through the mid-range, but a full pound lighter on the scales as well. If you just purchased your $10,000 plus Husqvarna RE or KTM FE and still have $1099.99 burning a hole in your pocket, I approve of this new system Lil D and the boys over at FMF developed. Head over to or give them a call at (310) 631-4363 to see when this system will be available. 




2017-2018 Honda CRF450R And CRF450RX Engine Mounts


For 2018 Honda went slightly softer on the top engine mounts of the CR450R. This was to give the bike a little more compliancy (straight line stability) on square edge and choppy terrain. However, if you have listened to my podcasts you will know that the 2018 Honda CRF450R can still feel a little rigid when the track gets hard packed and choppy. When the track is soft the Honda performs at its best, but since we are on the west coast and our dirt isn't as soft as east coast dirt, I wanted to get some more bump absorption out of the Honda chassis. The 2018 Honda CRF450R is a reactive, easy to maneuver machine and that is just a couple of its strong points, but after saying that it also can be a couple of it’s weakest points as well (when it comes to faster type tracks). You get what I am throwing down to you? If you don't, let me explain: If you're a vet, heavier guy or novice type rider that has a hard time cornering, the 2018 Honda CRF450R is a dream. If you're a faster, lighter type of rider, the Honda can be a hand full to ride when you start to push the boundaries a little. Yes, it won the 2018 Keefer Inc. Testing  450 MX Shootout because it has a great engine, is easy to corner and has a set of fairly good stock suspension. What it does lack is some straight line stability and consistency when you start to really push it on rough tracks. You may not know who Kris Palm is, hell I don’t know much about him either, but when someone presents a part for me to test, I am usually not one to shy away from trying things that I think may help a certain bike. When Mr. Palm asked me if I wanted the option to try a bunch of his engine hangers for the Honda CRF450R, I was more than willing to try. Knowledge is power right? 



Now….. I am not going to type about every single combination I tried because I will be here all day typing and not riding/testing. The ones that I felt didn't work as good as stock aren't worth mentioning, but rest assured I went through several variations of these engine mounts to find the best setting that I think will be best for you Honda CRF450 owners. I don’t know which engine mounts Kris Palm will offer, but what I had to work with was the top aluminum engine mounts in soft, medium and stiff as well as front engine mounts (made out of titanium) that come in a 4.0 thick/4.0 hole, 4.5 thick/4.0 hole and 4.5 thick/7.0 hole. I also tried the engine mounts on the 2018 CRF450RX for you off-road guys and incorporated which combo worked best with that machine. Just like in professional racing, changing the engine mounts and the affect it has on the bike is a rider preference thing. It may not be needed for every type of rider, so if you feel like you like the way your Honda rides than don’t worry about this test. However, one smart test rider told me back in the day “you are only as good as what you try”. Some riders like a feel of a certain engine mount and stick with that year round, where others will change their mounts for track conditions. Below are a couple of engine mounts combos that I think may be worth taking a look into.  



Medium Top Mount With Stock Front Mount

Tracks Tested: Glen Helen, Sunrise, Deep Sand Dez Track And Milestone

Best For: CRF450R and CRF450RX All Conditions



For better bump absorption and a slightly more forgiving feel on square edge, this was the best set up by far. This setting had more positives at each track I tested at and had a minimal negative affect on chassis balance. The medium top mount increased my rear wheel traction and gave me more front end feel on flat, hard packed corners. The Honda CRF450R kept its great cornering ability in tacky and soft dirt, but increased its cornering capability on hard pack with this medium top mount installed. Straight line stability was also a noticeable positive change as the Honda’s chassis felt less reactive (or more planted) on throttle which let me roll the throttle on sooner coming out of corners. Off throttle the CRF450R didn't have as much of a wiggle as it did with the stock mounts installed. The only negative for me was a slightly slower feeling on lean in (into corners). Again, the Honda with the medium top engine mounts installed wasn't as reactive, so it took slightly more work from the rider to get into ruts. To me that is ok as I can sacrifice a little “tip in” character for some added stability and rear wheel traction. Unlike what some other magazines will tell you, having a slower reacting machine doesn't mean it will corner bad. To me you will be able to get into the corner better now because the Honda has a more of a planted feel once you chop the throttle to set up for corner.  



Medium Top Mount With 4.5 Thick/4.0 Hole Front Mount

Tracks Tested: Glen Helen, Sunrise, Deep Sand Dez Track And Milestone

Best For: CRF450R In Soft/Sandy Conditions  



The stock front engine mount has a thickness of 4mm and is made of aluminum, but the bottom engine mounts Kris Palm offers are titanium. This means no matter if the dimensions are the same the flex character will obviously be different (because of the material difference). when going back and forth to different tracks I found out that the medium top mount and the 4.5 thick/4.0 front mount hole combination works best in sand and soft dirt. I felt the medium top engine mounts were better on compliancy, but it did suffer a little side to side flickability. With the titanium 4.5 thick/4.0 hole front mount and medium top mount it brought back that lightweight feel in corners and helped tip in. I didn't like this combination as much in hard pack situations because it brought back some of the harshness on small chatter bumps and square edge. If your track is soft with bumps that break away, this is a great combination that gives the rider some added soft dirt bump compliancy on straight line and gives the Honda more quickness (lightweight feel) in cornering situations. 



Stiff Top Mount With 4.0 Thickness/4.0 Hole Front Mount

Tracks Tested: Glen Helen, Sunrise, Deep Sand Dez Track, Milestone

Best For: CRF450R In Tight, Rutty, Jumpy Conditions



I went back and forth with this setting a couple times (on the same day) just to be sure I was feeling what I thought I was feeling on the track. Usually when I see “stiff” I shy away from it pretty easily when it comes to the Honda CRF450R, but this set up worked great for tighter tracks with medium to large sized jumps. With the stiff top engine mount, 4.0/4.0 front mount the Honda had a solid (less wallow) feeling to it when landing and kept great front end traction through long, deeper style ruts. This is not something that is particularly great on rough tracks, but if the track serves up some acceleration chop, long ruts, jumps with shallow landings and has good traction this combination was worth mentioning. It made the Honda slightly more flickable in the air and sudden direction changes (cutting down early from a berm or blown out rut) were better than stock engine mount setting. When I tried the medium top mount and 4.0/4.0 front mount the CRF450R flexed too much and become wallowy in the rear. Now I am just speculating here (because we don't have much arenacoss type tracks in California), but I feel like this could be a great setting for you east coast winter riding guys that have those indoor facilities to moto inside.  



Now here comes the tricky part. Kris Palm doesn't have a website set up yet because he really hasn't started pushing these engine mounts that hard. So if you're interested in getting a hold of him, maybe to get a set, you will have to reach out to him via a Direct Message on Instagram @kris_palm. If you don't know what a DM is, try Facebook. If you don't have any of that email me and I will try to get you in contact with him. I told you it was tricky! It’s almost like the movie Fight Club, where the first rule of Fight Club is you don't talk about Fight Club. The top engine mounts will run you $169.95 and the front engine mounts are $89.95. How can you pay? Get a hold of Mr. Palm and he can fill you in. Like I said, it's like an underground club that you must know the password to get into.  


If you have any reasonable questions about this underground Fight Club type test please feel free to email me at  


Yoshimura RS-9T Full Stainless System (2018 Honda CRF250R) 

It’s no secret that the all-new 2018 Honda CRF250R is lacking some bottom to mid power when compared to the other competitors in the 250 class. Seeing as how I’ve been logging a lot of hours on the machine as of late, I was designated to be the main test rider for the full RS-9T stainless system. Installing the new full system took me less than 20 minutes and the instructions were very detailed. All of the parts that came inside the box fit perfectly and no swear words were thrown while installing the Yoshimura exhaust.. In my opinion, Yoshimura is one of, if not the highest quality exhaust manufacturer in the industry. In my full time job I work in an R&D department of a welding shop and I can tell you first hand that the quality, fit and finish of a Yoshimura exhaust is impressive.


Now to the part that everyone wants to know... Does the Yoshimura help the little red screamer? The simple answer is yes, but who likes simple answers? Not us! With the stock system, the Honda pulled nicely from mid-range to the super high rev limiter, but when exiting corners and trying to grunt up obstacles, the engine needed some help. The best way to explain the stock feeling CRF250R is that it’s similar to a 125 two-stroke. By saying that I don’t mean it’s as slow as one, but I felt like I had to shift my riding style from four-stroke to two-stroke mode. I had to ride a gear lower at times in corners (than other 250F machines), and if I didn’t, it took a bit of clutch feathering and more shifting to get the bike pulling hard again.


As soon as I fired the bike up with the new exhaust it was clearly a bit louder, not obnoxious, but a nice, throaty sound that was deeper and less raspy. I tested the stock system back to back with the Yoshimura system on the same days, so it was cool to see the places on each track where the bike really felt different. The most noticeable place the bike felt better was out of tight inside ruts that exited up faces of jumps. With the stock system I had to slightly slip the clutch all the way up the lip (to be able to clear the jump). When I bolted on the Yoshimura system I could leave it in that same gear and just use the meat of the new found power to pull me up and over those types of jumps. Where I had to be in second gear and then scream the bike on the exit with the stock system, I could now be a gear higher and use the smoother/stronger part of the power to exit the turn with the Yoshimura mufflers. From mid to top I didn’t notice any real added power gains, but I also didn’t feel like the top end suffered in order to fix the bottom end. I’m by no means saying that bolting on an aftermarket exhaust will make your Honda feel like it has a Yamaha 2018 YZ 250F bottom end delivery, but it definitely helps close the gap and make the bike more enjoyable and easier to ride. If you have a 2018 Honda CRF250R and feel like you’d like a bit more bottom-mid range power I’d definitely look into the RS-9T system. There are three options Yoshimura offers, the slip on mufflers ($789.00), the full stainless system ($977.00), and the full titanium system ($1499.00). Admittedly none of these are super cheap options, but it is one of the few things in today’s four-stroke world that provides a true bolt on benefit. Besides, if you were cheap you’d still be riding your old clapped out POS instead of your sweet 2018 Honda. -Michael Allen 


I concur with Michael Allen on these findings. Michael is a great off-road rider and is an improving novice type of motocross guy. In order to please a wide range of abilities and riders when making an exhaust is not and easy task. I feel like Yoshimura has done that with their 2018 CRF250R exhaust system. I get more rpm response down low and it adds some excitement to the crack of the throttle. I love the chassis of the new generation Honda CRF250R, but it is hurting for some bottom end, in stock trim. The Yoshimura helps wake up some of that bottom-mid range and instead of getting a hollow/empty feeling down low (especially when the dirt is tilled deep), now I have some more “meat” to work with coming out of corners. I still can’t run third gear in corners, but I most certainly can shift earlier coming out of them. I also agree with Michael that the Yoshimura muffler didn't lose any up top when compared to the stock system. If anything I feel like it was a little stronger than the stocker, which is impressive. I also think the stainless system is just as cool as stock (because I am saving money), but you will only be losing a little over half a pound instead of over three pounds with the titanium version. -Kris Keefer

Yoshimura RS-9T Full Titanium/Carbon Muffler System


The 2018 Honda CRF450R is a refined version of the 2017, albeit a better one I may add. If you listened to the muffler shootout podcast you would know that this is a great muffler to add to your new Honda CR450R. If you haven't listened do yourself a favor and click on the podcast tab and look for the "Honda CRF450R Muffler Shootout Podcast". Once I got my hands on one and I took it through the ringer of the shootout process, I knew Yosh had put some R&D time into this system. We know Yoshimura works closely with the Factory Honda team here in the states and have seen the RS-9T muffler on Cole Seely and Ken Roczen’s new bikes so it's no surprise that they work pretty damn well. The Yoshimura RS-9T system only comes in a dual can set up (no single mufflers are available from Yoshimura) and is a three-piece slip fit design. Installation of the system was painless and took 15 minutes to install, which was nice to do when at the track swapping mufflers.


Once installed and on the track the Honda’s exhaust note turned from high pitch 250F’esq to a deep throaty more traditional 450 factory race bike sound. The crack of the throttle (or RPM response) is slightly smoother and less crisp, but bottom end pulling power is increased over the stock muffler. Rolling out of corners, in second gear, feels like the rear wheel has even more traction than stock and was more controllable while accelerating out of hard pack corners. The slightly smoother RPM response takes away the Honda’s excitement feel ever so slightly, but helps you gain a little more control coming out of corners. The mid range pull is healthier than stock and while the stock system had a tough time pulling third gear in tighter corners (without a gearing change), the Yoshimura system will give you an easier time rolling third gear corners. With just the flick of the clutch lever (in third gear) the Honda will be in the meat of the power once again and have you down the straight in a hurry. We noticed top end and over-rev was as good as stock (which is great). It pulls adequately down the straights in second and third gear and there wasn’t a time where I thought to myself  “I need more top end pulling power”. Ehhhhhh. No. You could tell Yoshimura was focused on bottom to mid-range pulling power when they designed this muffler system and they succeeded in doing so. It is also impressive that they didn’t lose any top end and over-rev in the process.


After weighing both the stock and Yoshimura RS-9T systems you will be saving 1.9 pounds, which is a nice chunk off of a already heavy (on paper) motorcycle. This is a significant weight loss but for $1,499.00 it is a very pricey bolt on modification. If you are looking to save a little money Yoshimura offers the stainless steel/carbon version for $977.00, but you will not be saving much weight (only half a pound). I really like the craftsmanship that went into the Yoshimura system. The welds are flawless and the mufflers tuck up inside the side number plates for a stealthy, compact look. If you’re looking for al little added giddy up and bling from your new 2018 CRF450R, the Yoshimura RS-9T system will help you on the track, but your wallet will be not as fat. This is the price we pay for getting some extra HP and a better-looking muffler right? This is one of my favorite systems for the 2018 Honda CRF450R and it has held up great over time (over 20 engine hours). You can head over to to get yours or call them at 800-634-9166.



If you have any questions about this test please feel free to email me at 

Dubach Racing (DR.D) 2018 Yamaha YZ450F Slip-On Muffler

Before I start this review I am going to go on a little rant here, so bare with me. Mufflers are always a hot topic when it comes to horsepower, especially when you get a new bike. I know a lot of riders out there get a muffler system before they even ride their new bikes! Ride your new bike and break it in before purchasing any muffler please! See what you're working with and purchasing, so you know if its better than stock. Because if it’s not better than stock, what is the reason you purchased it in the first place? To look cool. To drop some weight. Those two statements would be the only answers that are acceptable when someone asks you why you have a new muffler on that bike that has an hour meter that reads 0.1 hours. Ok moving on…….. 



When it comes to Yamaha motorcycles, Doug Dubach is a name that comes to mind immediately right? Doug has been a Yamaha test rider for 87 years and is almost that old, but don't tell him I said that. Seriously, Doug knows the ins and outs of the 2018 YZ450F like the back of his hand, so I was anxious to try his slip-on muffler when I reached out to him. However, instead of trying a full system I wanted to do something different and just try a slip on muffler system. A slip on system is only the rear section that keeps the stock headpipe and mid-pipe intact. I installed the DR.D stainless muffler system (that saves just over one pound compared to stock) in only 3.5 minutes. 


I am very picky when it comes to mufflers and how they deliver the power to each bike I evaluate. The DR.D slip on keeps the stock feeling YZ450F bottom end pull intact, but maybe softens the low end RPM response just a tad. This is only noticeable on super loamy style tracks, but helped rear end traction feeling on hard pack style tracks. Losing a little RPM response and gaining some rear wheel traction is not a bad thing on this beast of an engine. I want to note how hard it is to build a muffler system that keeps the low end pulling power feeling of a stock 2018 YZ450F as I have tested several full muffler systems that had less bottom-end than stock. Where most of you will feel the difference between the stock muffler and the DR.D is mid range pulling power. The mid-range meat that the DR.D system delivers is impressive and gives you a better pull in second gear and helps the third gear transition when shifting. With the stock Yamaha system (with stock gearing) it was hard at times to carry third gear through corners, so shifting to third immediately after the corner was a must. With the DR.D system I have the freedom to leave the Yamaha in second through the corner and shift early without the blue machine falling off the power much. Or if you choose to run third gear in corners it picks up the power slightly earlier and helps lazier/lug heavy riders get out of the corner quicker with more rear wheel traction. Top end is also slightly increased over the stock muffler as you are able to hold each gear (well, to be honest the only gears I used was first through fourth) slightly longer. If you're looking for more over-rev this isn't the muffler you are looking for because the DR.D system keeps all of the stock feeling over-rev on the track and doesn't gain anything extra. This isn't a bad thing as the standard YZ450F power character revs out just fine. 



The DR.D slip on stainless system is the best slip on system that I have tried on the 2018 Yamaha YZ450F and will only set you back $395.00. Not to mention that you’re not losing any horsepower and gaining some mid-top end, while getting some added rear wheel traction. The DR.D muffler system comes with quality packing, has a nice sound to it without it being obnoxiously loud, is easy to re-pack on your own and doesn't blow out quickly. If it comes time to re-pack and you don't want to do it yourself, Dubach has an exhaust packing service where you can send in your muffler and he will re-furbish it for you for a small fee. If you're wife is having a conniption fit about you spending more money on your new bike you can tell her you're saving around $600.00 by not going to a full system. You’re actually compromising and doing her a favor! You're welcome fellas! You can check out all of the mufflers that DR.D makes over at


If you have any questions about this test, please free to contact me at 


2018 Yamaha YZ450F Dubach Racing Engine Relocation Kit


The new 2018 Yamaha YZ450F corners much better than in previous years, but still can feel like it has some front tire pushing when there is nothing to bank off of. This is not as drastic a feeling as it was in 2017, but some riders want more front end bite out of the blue machine, so we thought we would try Dubach Racing’s engine relocation kit. Doug has had this engine relocation kit out for quite sometime and they have worked well on older model YZ450F’s. I personally didn't think the engine needed to be tilted more forward than it already has for 2018, but I can’t keep well enough alone, so I decided to give it a go. Dubach’s kit only consists of two small bushings that tilt the 2018 engine 1.5mm forward and only takes around 30-40 minutes to install. If you want to understand better on how to put the kit in you can go here: and check out Doug’s instructional video he did. This video is dated, but most of what he is doing to this older YZ450F applies to what you will do to the 2018 version (without the new engine mounts of course). The 2018 kit only comes with two collars/bushings as you will use all your stock/existing engine mounts.



Before you go purchasing Dubach’s Engine Relocation Kit make sure you have tried doing some things to your 2018 YZ450F, like raising your fork up 5mm (flush is stock) in the clamps and be sure your sag is set at 104-105mm (100-102mm is standard). I don't recommend going higher up (with the fork) than 5mm to get more front end bite, as going up any higher will dramatically hurt your straight line stability. 


So what exactly did I feel on the track once the Dubach Racing Engine Relocation Kit was installed? A lot actually! “Keefer, it’s 1.5mm, how much difference can it be”? Well once I got out on the track, I immediately noticed how reactive the front wheel was to my steering. I have a ton of hours on the stock 2018 YZ450F and I know how it reacts once I turn the handlebars. The Yamaha with the DR.D Relocation Kit on was almost Honda-like and gave me the feeling of having the front tire tucked in more towards the engine. It took me around two laps to realize that I needed to drop the fork back down in the clamp and re-check my sag to get it to where it wasn't as reactive to handlebar movement. I dropped the fork back down to 2mm up in the clamp, set my sag at 105mm and did a couple motos. The 2018 Yamaha YZ450F has better tip now in coming into corners and I can feel the front knobbies biting down a lot more through flat corners. This was all for the better, however I noticed a little less straight-line stability and slightly less rear wheel traction coming out of hard pack corners. I adjusted my fuel/ignition map on my Yamaha Power Tuner App to help mellow out the low-end delivery and that rear wheel traction returned! The straight line stability loss that I experienced was very slight, but was mostly noticed while on-throttle, off-throttle stability improved slightly. When chopping the throttle the little wiggle I used to get in the chassis has now settled down some. On throttle side to side movement fro the rear end has slightly increased. I wouldn’t say that the DR.D kit makes the 2018 Yamaha YZ450F twitchy, but it will make it very reactive to any slight steering movements you make. If you are looking to make the Yamaha a more reactive machine and slightly more agile, this kit will do just that! 


At the end of the day, I prefer the stock tilt for the way I ride. Let me explain this…. I don’t mind a slightly slower turning machine as I can corner fairly good. I do need front tire traction as I am a front end steering rider, but having a little less reactive machine makes me feel stable and I am able to push harder (hence more stability). Now, if you’re a rider that needs every ounce of lean, front-end bite and cornering capability, this is a great option for you. I have several riding buddies that prefer the Honda CR450R over the YZ450F because they want their machines to corner with ease and with more front wheel bite. Having this DR.D Engine Relocation Kit installed made those friends happy with the 2018 YZ450F now. The DR.D Engine Relocation is available now and will set you back $89.95. 


If you have any questions about this test please feel free to email me at

Enzo Racing Spring Perch And Sub-Tank System For 2018 YZ450F KYB SSS Fork Product Review 

The 2018 Yamaha YZ450F is the best suspended motocross bike that is available, but that doesn't mean I’m going to leave it alone. When I got the call from Enzo Racing’s Ross Maeda to see if I wanted to test a couple fork parts, I was more than happy to see if we can make the KYB SSS fork even dreamier. 



We didn't go with a fork re-valve as we wanted to see if the parts provided made a noticeable change to the existing stock 2018 valving. I personally like this approach because if you're currently happy with your valving and just needed to fine tune this was a great test to see if the Enzo parts provided could make a difference. I am 170 pounds and a front end steering rider, but I felt the stock fork setting (once broken in) was a little soft on de-cel and jump faces/transitions. Ross installed a 5.1 fork spring (5.0 is stock) and sent me out on the track to see if I liked that change, which I did. It provided a little more hold up and I could ride over the front more while being more aggressive. It did give me slightly less front end traction on lean in (coming into corners), but the trade off for me was well worth it. I did however need a little more comfort on the top part of the fork’s stroke (acceleration, light bump absorption).



Next up, Ross installed the Enzo Technica fork spring perch. This perch flows more oil and is a machined aluminum piece that Ross at Enzo makes for several different models. Once the spring perch was installed, they sent me back out on the track and I immediately noticed a difference on lean angle traction. The front end traction that I lost with the 5.1 front fork spring I gained back and then some. With the spring perched installed I immediately felt more front end bite coming into corners, especially on flat corners. Where the front tire felt like it was riding more on top of the dirt now I could feel the knobs digging into the terrafirma more when I went to cut down into a rut. Another part of the fork’s action that was improved was on braking bumps. The stock Yamaha fork isn't harsh by any means, so I guess the best way to describe what I felt was more of a plush feel when hitting bumps (on or off throttle). Let me try and describe what I am feeling to you all while you are sitting there reading this: Let’s say the stock fork is a basketball that you drop 10 feet up in the air, to the ground. The Enzo fork with their spring perch installed is like dropping the same basketball to the ground, but now from only from 5 feet up in the air. This is the sensation that I get when riding that is most describable to you all. It cuts the KYB fork’s hit to each bump (or sensation to your arms) in half. I was so amazed that I had to go back to the stock spring perches just to be sure what I was feeling was in fact that much better. If you listen to my podcast, you know how I rate each test as it’s off of a numeral system. On my sheet the numeral system would look something like this: Stock fork = 3 baseline. Enzo Fork with spring perches installed = 3.5. A noticeable, positive change! 



For the last test Ross installed the Enzo Sub-Tank System that was so popular several years ago. However, this is not the same system that was around back then, this is more like a 2.0 version of the Sub-Tank System. The Enzo Racing Sub-Tank system is adjustable by bleed setting screws on the side. This adjustment is tunable using a small flat blade screwdriver. The standard setting is 4 complete turns out (counterclockwise) from maximum (all the way tight clockwise). This adjustment setting creates a restriction in the tanks which will control the air compression volume depending upon the speed that the fork is compressing. In simpler terms, the tighter the adjustment, the sooner the firmness of the fork will occur. If you are experiencing bottoming, you should turn the adjuster clockwise IN 1 turn at a time. If the action feels too stiff, turn the adjuster counterclockwise OUT 1 turn. I left it on the stock setting for this test, just to get a feel for what it does. What I can tell you is that the fork still has that plushness and front end bite it had with the Enzo Spring Perches, but I can feel more of a damping feeling near the end of the fork’s stroke now with the Sub-Tanks installed. This wasn't a huge improvement, but I could hit faces of jumps harder and flat land singles further. Basically this system works great if I was racing and getting aggressive while trying to make the pass on a rider. I like how putting these Enzo Sub-Tanks on did nothing to my newfound front wheel traction that the Enzo spring perches gave me. 



At the end of the day I got an even better (more comfortable) feeling front end and didn't have to re-valve my fork. I will be trying a full Enzo re-valve in the future, but I thought for keeping the stock Yamaha’s valving in and only adding a few pieces to the fork, it really helped the fork’s action and ride attitude of the bike around the track for the better. The spring perches and sub-tank system are available now. You can call Enzo at (714) 541-5218 for pricing or visit 

For any questions about this test or any other burning questions please feel free to email me at kris@keeferinctestingcom.   


FMF Factory 4.1 RCT Full Muffler System Product Review

It’s hard sometimes to get more power out of newer four-stroke models nowadays with aftermarket mufflers systems. To be honest with you most stock systems are pretty damn good and aftermarket muffler companies like FMF work really hard to try and give you that little extra bit out of a system. I can sit here and tell you that FMF is one company (of only a couple in existence) that will take the time to listen to the proper feedback (either from me or other media testing outlets) and make the necessary changes to alter a new four-stroke machines power in the right direction. The key word here is “alter” and maybe not “gain”. Yes, in this article you will hear me talk about “gaining” a little pulling power, but to me the configuration of the 2018 Kawasaki KX450F FMF 4.1 RCT Muffler System power delivery is more “altered” from stock than anything. 



The stock power of the Kawasaki is unchanged for 2018, but that doesn't mean it’s not a great bike. The engine has a snappy throttle response with a free feeling, on de-cel, without much engine braking. Once rolling on the throttle, the power is not as strong as the Honda or Yamaha, but still creates a lightweight feeling on the track. I didn't necessarily need more rpm response with the KX450F, but would like more meat through the mid to top end range. Bolting on the KX450F FMF Factory 4.1 system is bar far the easiest system I have bolted on for 2018. It took me literally two full songs on the Metallica Pandora station to change the muffler. The Kawasaki is a light bike stock, but I chose to go with the full titanium system that let me drop 1.8 pounds from the stock system! Visually the titanium FMF system is one of the most stunning aftermarket mufflers you can put on a bike. I love the blue anodized finish as it looks good on almost every make and model machine. 



On the track the FMF 4.1 on the KX450F makes as much bottom end power delivery as stock and keeps that peppy/exciting RPM response. Where the FMF 4.1 system really impressed me was mid range pulling power when exiting corners. The stock system feels empty in this area, but the FMF fills the power-feeling in through the mid-range. What I mean by “fill the power in” is that the FMF system actually feels like it pulls as soon as you shift into third gear unlike the Kawasaki’s power where it feels like it lacks some pull through the mid-range. There is a dip in the Kawasaki’s mid to top end power and the FMF brings back some meat through that area, which in this case “fills in” that area. Top end is also increased slightly and you get increased pulling power near the end of each straight with the FMF. 


I did go back and forth with the couplers on the KX450F and came to the conclusion that although the lean coupler is better for bottom-mid range power, the standard coupler is slightly better from mid to top end. I will have to say when you do go to the lean coupler that the KX450F will pop more on de-cel with the FMF system than the stock muffler. With the standard coupler de-cel pop is minimal and not as noticeable with either system. 



At the end of the day the FMF 4.1 RCT full muffler system is better than stock and that is not easy to do these days. It takes off some weight and looks better than the stock monstrosity. To me there is no negative with the FMF system and that is rare in an aftermarket muffler. I have tried other FMF mufflers, on some other models with some negatives, but the KX450F muffler is a good buy. Please note that re-packing of the FMF muffler is important for the can’s lifespan. The muffler portion (or can) will start to leave hot spots/scarring when the packing starts to burn out inside. Once you start seeing these “hot spot scars or markings” on the muffler, remove and re-pack is recommended. FMF sells re-packing kits and taking the can apart to re-pack is not that hard to do. I get around 10 hard engine hours (these are pro type hours) before I see these markings and have to re-pack. If you run it past the recommended time, you run the chance of hurting performance and damaging the core (or perf) inside the muffler. Kudos to FMF for building a good KX450F system and moving the power around slightly and gaining a little as well. If you have any questions about this test please email me at 


Bonus: If you listen to my Keefer Tested podcast you know that I rate some parts and motorcycles by a numeral system. I wanted to break down the FMF system to the stock system for you all below. If you don’t know what these numbers mean, please go listen to show #3 “How To Test” and you will understand better what these numbers mean. 



Bottom End: 3/3

Mid-Range:  3/3.5

Top End:      3/3+

Over-Rev:    3/3+

Bottom End RPM Response:  3/3

Mid RPM Response:               3/3.5

Top End RPM Response:       3/3+

Think Technology Lite Seat Foam and Lite Seat Cover 

 There is a saying in racing that goes something like this “worry about the ounces and the pounds take care of themselves”, and Think Technology seems to live by this saying in everything they do. Think sent us replacement “lite” seat foam as well as a “lite” seat cover to go with the long term 2018 Honda CRF250R that I have had for some time now and I thought they forgot to put the foam in the box when UPS dropped it off (I’m not kidding, it’s that damn light!). I never really thought about seat foam and covers being a factor when it comes to the overall weight of a 200+ pound motorcycle, but when I felt compared foams, side by side, I was rather impressed. I honestly didn’t weigh them side by side since the scales I have don’t register that low, but I can tell you that the feeling in your hand is impressive and the claimed difference Think Technology says is close to one pound! I believe it, because it actually feels more than a pound on my human hand scale. 

Stock seat with Think foam and cover not installed yet.JPG

When I took off the original seat cover and foam I initially noticed the stock foam was still slightly wet from the recent washing a couple days before. The second thing I realized was that the stock foam not only goes on top of the seat pan, but the side overlaps and slightly goes around and under the stock seat pan. After all the stock parts were removed and I went to put the new foam on I realized that the foam no longer wrapped around the side and under the seat pan, which didn’t seem like a big deal at the time. The foam fit nicely on top of the pan and the new cover wrapped around the foam nice and tight with plenty of material left over on the bottom to staple. 

hink installed right side.JPG

The new cover has a cool look to it with the custom “120” Think put on the front of the cover making it custom for Kris (I’m not fast enough to have my own number). Installing the seat on the bike was almost easier than the stock one, but there is a reason for that. Remember how I said the new foam didn’t wrap around the bottom of the seat pan? Well, that now created a small gap all the way around the seat between the seat and the plastics, so much so that you can see daylight between the seat and the gas tank. This gap also left the seat pan a little loose on the side of the gas tank and lets the seat rattle slightly more than stock. However, where the seat hooks to the tank isn’t wedged tight, you really don’t notice it when riding, you notice more in the pits riding out to the track. That being said, those are the only negative things about the performance of the Think Technology seat foam. On the track those couple negatives go away when you feel the nice firm seat foam, not hard, but firm which never broke down at all, as well as the grippers sewn into the cover that really keep you in place on the seat. In addition to customizing the seat with your number (if you’re fast enough to have a number) Think Technology will also put a seat bump in your specified location for an extra $40. 

Think 120.JPG

After putting many hours on the Think foam and cover I’m impressed with the holdup of the product, the cover has only slightly lost its bright red look due to all the dirt and the foam hasn’t broken down or got water logged after further inspection. I did not notice a weight difference on the track, but maybe Kris can feel that kind of stuff more than me. The other cool feature of the Think foam is that it’s a closed cell foam (which comes from the aerospace industry), this means during washes it won’t absorb or retain water, which is good for two reasons; one it will not retain the water which makes it heavy, and two it will not stay water logged and ruin the foam like stock seat foam can do. Now to the part that will scare a lot of you away, the price of the Think foam is $299.99 (plus $40.00 if you want a bump) and the cover is $59.99. I know this is a lot of money (anything related to aerospace isn’t going to be cheap), but if you are into saving every ounce (as some of you crazy weight biased people are) as well as not having to sit on a water logged seat ever again, I’d definitely look into Think Technology. -Michael Allen

 There is more of a gap between the Think Seat and fuel tank compared to stock. This is common with aftermarket foams and we may have pulled this seat cover on too tight up near the front. Check back to for an update as we install another cover on to check gap. 

There is more of a gap between the Think Seat and fuel tank compared to stock. This is common with aftermarket foams and we may have pulled this seat cover on too tight up near the front. Check back to for an update as we install another cover on to check gap. 

 Stock seat and cover comparison. 

Stock seat and cover comparison. 


Second Opinion: 

I have used the Think Technology foam on other machines like a Yamaha YZ450F and have come to the same conclusion as Michael. I like the firmness of the seat and the fact it hasn't got heavier over repeated washes (over the course of a year). As you know I ride a lot, so I wash my bike a crap ton as well and it hasn't broken down. I have heard through some grumblings that the foam shrinks up over time, but I haven't seen this happen yet. Like I said, I have had mine on the Yamaha over a year now and all is well. This is a niche product, but I like testing these niche pieces because its not the norm. It’s expensive, yes, but it’s up to you to decide if it’s worth the money. It’s a good product, but to me gives you no real advantage on the track. The advantage is the lifespan and weight consistency of the foam. -Kris Keefer

Pro Taper Fuzion Handlebars

The Pro Taper Fuzion handlebar has been around for a while now and was a totally new concept to the off-road world (for crossbar lovers) when it was released a few years ago. The flex locking system allows riders to choose between a stiffer, more controlled handlebar feel or a softer more shock absorbing feel depending on terrain and rider preference. Changing the bar from “Locked” to “Unlocked” takes only seconds by simply turning a knob. The Fuzion utilizes Pro Taper’s exclusive aluminum alloy, 4mm wall design for lightweight, strength and comes in six different bar bends.



Depending on what type of bike I am riding depends on if I like running a crossbar type handlebar or not. For example when I am riding a Honda I like to have a crossbar because they come standard with one. When I ride a Yamaha I go to a handlebar without a crossbar. Why? You guessed it, because they come stock with that style. I usually can tell the difference in stiffness when I go back and forth between each type of bar so this made me want to really test this Fuzion bar. 

The 1-1/8 Fuzion handlebar weighs in at 1lb, 15oz. and was put on several of my test bikes. The easy-to-adjust locking system can be adjusted by simply taking the bar pad off and turning the knob in the middle of the crossbar. If you’re used to running a 7/8 bar with a crossbar on your bike, but want some added strength, the Fuzion is a great option. The downside to using a standard oversize bar with a crossbar is getting added rigidity through the bars that could be hard on the arms/wrists. Setting the Pro Taper Fuzion to the “unlock” position was most noticeable on the 2018 Honda CRF450R due to it being a more rigid feeling chassis. In stock form the Honda comes with a 7/8 handlebar and putting the Fuzion bar on gave me only minimal gains in stiffness through my arms. On braking bumps and hard slap down landings the bar flexed as if I didn’t have a cross bar on. Does it flex more than an oversize crossbar-less handlebar? After spending more time on both types of bars I would say it is very close.



I am very picky when it comes to handlebars and I felt that the Fuzion handlebar (when in the “locked” position) is slightly more precise (than on the unlocked position) when trying to corner on hard pack slick surfaces. Also, only a little more rigidity was felt on braking bumps and on flat landings when “locked”. The smoother the track surfaces the better the Fuzion worked in the locked position. However, 90% of the time I felt the Fuzion felt best when “unlocked”. Especially for the hacked out, choppy, desert tracks I test on.  A few tip overs and one big get off left me praising the Fuzion’s durability. This happened on the CRF450R and the handlebar got twisted in the bar mounts, but the handlebar itself wasn’t bent.


So at the end of the day why not just use an oversize non-crossbar handlebar you ask? The Fuzion handlebar eliminates having “crossbar lovers” cut his/her oversized crossbar handlebars (and avoiding potential handlebar failure to achieve desired flex when he/she demands a crossbar). I like that ProTaper addressed the need for this niche and picky people like myself. Especially for riders that need to see a crossbar yet have flex when he or she rides. Yes, it is more expensive than your average 7/8 handlebar, but it also will last longer in case you are a crasher like these dudes on MX Fails.

VP T4E Race Fuel Product Review 


VP has had T4 race fuel out for a while, but VP decided to come out with an updated version of the T4 and now it’s called T4E. What’s different? The VP employee couldn't tell me the specifics as it is a secret formula, but he said that I would notice a difference on the track compared to the standard T4. Hmmmmmmm....I was skeptical, but I gave it a go. 


Designed for stock or slightly modified four-stroke motorcycles and other off-road vehicles used in competition, unleaded/oxygenated and ethanol-free T4E (no the “E” doesn't mean ethanol) is a direct pour-in replacement for premium pump gas. Since pump gas has a short storage life and could cause greater need for repairs in the motorcycle industry due to its ethanol content, T4E’s 100 octane rating (R+M/2) provides greater protection against detonation. Compared with more expensive performance parts that increase power along only a small slice of the power curve, T4E claims to add 2-3 percent more power and better throttle response across the entire rpm range. I wanted to see if that “claim” was true and have been running it in several test bikes I have here. 


                                                            VP T4E is available now.

                                                           VP T4E is available now.

The biggest advantage of VP T4E over pump gas is our current pump gas (especially California pump fuel) contains ethanol, an alcohol-based alternative fuel manufactured by fermenting and distilling starch crops that have been converted to simple sugars. This is not good on the life span of the valve train, fuel pumps, and top end gaskets on small engines like a dirt bike. Ethanol in the fuel can leave a gummy substance that clogs fuel pumps (or jets on carbureted bikes) and causes early deterioration to head gaskets and O-rings and possibly shortening the life of your engine. Another major problem is phase separation; if water gets into the fuel this can cause the water/ethanol mixture to sink to the bottom of the tank where the fuel pick up is. Here’s a tip: If you are using pump fuel and you’re at a gas station and see a fuel truck filling the gas station’s tanks, go somewhere else, because chances are they are near the bottom of the reservoir. Water inside your engine can cause the fuel pump to stop working (seize up) and also can make your bike miss and sputter. 


Is their a on-track performance gain from T4E compared to the T4? Is the T4E worth the added cost instead of using pump fuel? For the average guy putting around on weekends, maybe not so much. Pump fuel is just fine. For the true enthusiast who rides hard and wants a reliable power gain, yes, it is. I ran five gallons of T4E in the Yamaha YZ450F and it took me less than three laps to feel the added throttle response (compared to pump fuel). Coming out of corners and rolling the throttle on in second gear I felt like the bike had more pulling power down low. Shifting in third gear I felt a better pull and the Yamaha actually ran slightly cleaner throughout the rpm range. I didn’t feel too much gain through the top end as most of what I felt was down on low rpm and up through the mid range. However, riding longer motos on a sandier-type track I noticed that the bike kept consistent power. Usually when I ride this type of track with this bike the power decreases a little as the bike gets very hot – but not so with the T4E. When comparing the T4 to the T4E the T4E does give me more bottom end than the T4. The mid range was close to the same. So if you’re looking for a little more bottom end snap/pull the T4E is the real deal. One thing you might have to deal with is a slightly different smell of the T4E. It is unique! My wife Heather thought a cat came into our garage and pissed all over the place, but to me it smells like race fuel. Just slightly different and I was fine with it! But……….You might want to find somewhere to store it, so the wife doesn't yell at you. If you’re in the market for a lower cost race fuel (versus some of VP’s higher-end products) that gives you power gains and helps your bike just run better, then the T4E is a good choice.


If you have any questions feel free to email meat

Works Connection Pro Pegs

Pro Pegs

Titanium Footpegs Review



          This version was an open cleat design that a lot of GNCC riders use for muddy conditions. 

         This version was an open cleat design that a lot of GNCC riders use for muddy conditions. 



Some people don't even take the time to think about aftermarket footpegs and just keep the stock footpegs on for the duration of ownership. The stock pegs are usually pretty good and do just fine, but for those of you who haven’t had sharp or wide footpegs you really don't know what you're missing. Pro Pegs titanium footpegs are manufactured with high-grade Ti-6AL-4V titanium. These Pro Pegs are lightweight, very strong and corrosion-resistant. Each piece of the footpeg is TIG-welded together and really is a work of art. The Pro-Pegs have a factory look with impressive strength characteristics. The Pro Pegs are 60mm wide (2.4 inches), weighed in at 345 grams a set, use the stock springs and are all hand made. They will set you back $269.95 and are fairly easy to put on. The only snag I ran into was that the stock springs are tough to line up with the Pro Pegs holes and takes some finesse/patience for the pin to line up accordingly. The Pro Pegs come with two fresh cotter pins, so make sure you use the ones that come with the pegs.  


 Once on I was very impressed that the Pro Pegs lined up flat, just like the stock pegs. With some other aftermarket pegs the stop was too long and cause the footage to be tilted upward somewhat. With the Pro Pegs the footpegs lay flat and move up and down freely with no restricted movements. The Pro Pegs that you see here are the Mud/Enduro style that don’t have the middle cleat, which I prefer. I like the open design to keep mud out of the footpeg as much as possible for maximum grip. They make a full cleat (which has a middle cross brace), but I chose this style to try on the 2017 Honda CRF450R. I have seen many top tier factory motocross teams run this design and wanted to see if it affected my grip on the bike. I have tried the full cleat Pro Pegs on past test bikes and didn't notice any extra grip with the middle cross brace added. I think the open design is more trick looking and gives the bike a factory look! 


  When installing remember to always bend the fresh cotter pin around to ensure it doesn't slide outward. 

 When installing remember to always bend the fresh cotter pin around to ensure it doesn't slide outward. 

The Pro Pegs teeth (all 18 of them) are sharp and much deeper than that of a stock peg. The amount of teeth on a footpeg is not as important to me as the sharpness of each tooth. Each tooth is much sharper on the Pro Peg (than stock) and although there are less of them, than a stock Honda peg, the grip that I get is much higher. I can feel the soles of my boots digging in instead of just riding on top of a dull footpeg. I feel more locked in with the bike and I am able to ride on the balls of my feet easier with these sharper/wider Pro Pegs. Yes, the Pro Pegs will eat the soles of your boots faster than the stock pegs, so make sure to keep an eye on the soles of your boots closely. I didn't notice any weight difference (on the track) or any odd vibrations through my boots with the Pro Pegs. 


The Pro Pegs are distributed by Works Connection and MotoStuff and are available now. If you are looking to get some added grip, want to really stick to your pegs and work on your technique these are a great choice. The Pro Pegs have outstanding quality and have been on my Honda for almost a year and still look great! 


Available at and

FMF Dual Titanium Factory 4.1 RCT Muffler System

Keefer Inc. Product Evaluation 

FMF Dual Titanium Factory 4.1 RCT Muffler System

The 2017 Honda CRF 450R has an incredible engine package stock. The snappy throttle response and free feeling of the motor makes this one of the most fun engine characters in the 450 class. This doesn't mean it can’t get better however. FMF wasn't the first to the game when the new generation Honda CRF 450R was released. In fact, FMF waited longer than it would of liked to release their 4.1 dual muffler system, but they wanted to ensure it wasn't just good on the dyno, but good on the track as well. I took delivery of FMF’s Dual Titanium 4.1 RCT muffler system and installed it in less than 10 minutes (which is a great time for me) and was able to head out onto the track. There were no joints that binded or misalignments when assembling the FMF system 

I have ridden with Yoshimura and stock systems on the 2017 CRF450R the most recently. I have a good feeling of both of these systems, so breaking down the FMF system was fairly easy to dissect on the track. The FMF 4.1 muffler system has incredible amounts of bottom end and throttle response. The bottom end comes on strong and the Honda keeps its exciting, crispRPM response feeling, but lets you run third gear through corners a little more than the stock or Yoshimura muffler systems can. Downshifting to second almost makes the Honda a little too much too handle with the FMF system installed (on roll on) through some corners. When going to the FMF 4.1 system I reverted back to map 1 (standard map) instead of map 3 (aggressive map). Since the FMF has so much bottom end I could use the standard map instead of having to use map 3 like I do on other systems. Mid range is broader and pulls farther than the stock muffler, so using third gear is almost the perfect gear for most tracks (with stock gearing). Through mid to top end the FMF system almost mimics the Yosh in pulling power feeling on the track. Over-rev isn't increased dramatically over stock, but I did notice that you didn't need to rev the Honda with system as shifting early was a welcomed attribute to the American made muffler. I did notice that the FMF system is louder than the Yoshimura and stock systems, but keeps a race oriented deeper sound. 


It takes you a little while to get accustomed to the sound once on the track, but the good news is that the muffler packing has lasted past the 12 hour mark and hasn't changed much to the ear. I used to get only 8-10 hours on other FMF muffler systems, but the dual Honda system has proved to be more durable. the system is light at 8.3 pounds and will remove a couple pounds off of your stock system. 

In my opinion this is one of the best mufflers that I have tried for the 2017 Honda CRF450R. Yes, it is louder sounding than others, but the increase in power feeling on the track makes it hard to beat. If you're looking for an exciting feeling muffler system that performs as good as it looks the FMF Titanium Factory 4.1 RCT Muffler System is a good buy. At $1299.99 it is slightly less money than its competitors and for as long as we all waited for Don and the fellas at FMF to get it out there, it is well worth the wait. You can go to to order yours. 

Have any questions about this test? Feel free to hit me up at and I will do my best to answer any reasonable questions for you.