If you subscribe to the “Keefer Tested” podcast you were able to hear a lot of information on what I have done to my 2017 Yamaha YZ450F. It is no secret that I am very fond of this machine and am looking forward to swinging my leg over the 2018 version soon. I have over seventy total hours on the 2017 YZ450F and have had no engine failures to date. I am on the same top end since I received the Yamaha and the valve clearances are still in spec. This has been a reliable machine, but I wanted to break down all the modifications I have made to the YZ450F, along with some tips and tricks you all can do to yours at home.
Suspension: Even though I love the stock suspension as it is the best production suspension on the market, I needed more hold up so I took my stuff to Enzo to get it dialed in for me. The stock KYB suspension is fine when new, but once broke in the fork can dive a little too much on de-cel (especially with the heavy engine braking feel that the Yamaha comes with). Enzo changed the valving and went with a heavier .51 fork spring as this helped with balancing the bike out coming into corners. The shock spring rate stayed stock, but the valving was changed internally. Enzo put on one of their high speed adjusters that helped with rear wheel traction over acceleration bumps. Overall, I happy with the Enzo suspension as it still has a lot of the comfort that I love from the stock setting, but with the performance I am looking for when I want to get out of my comfort zone a little.
Ignition: I played with maps (on the stock ignition) and I have attached a good starting map for all of you out there to try. This map comes on smoother on low rpm, but broadens out the mid-top end. This setting also seems to help with some de-cel pop that I have experienced with the Yamaha on warmer days. The standard ignition is just fine, but if you’re looking for more power than you might want to try the Vortex ignition. I used the Vortex box and loved how it hits harder down low, but didn't lose any rear wheel traction. In fact the Yamaha feels more connected at the rear wheel with the Vortex installed. The Vortex is a pricey $500.00 investment, but gives you more power everywhere. If you're looking for more over-rev the Vortex ignition gives you an extra 300 rpm to work with without sacrificing much reliability. 40 of my 70 hours on the YZ450F have been with the Vortex ignition and the Yamaha runs cleaner and starts just as easy as the stock ignition.
Muffler System: I have tried many options in this category and came up with only three to recommend to you. Stock, FMF and DR.D. These three mufflers each has their advantages and does one thing better than the other. If you’re looking for an all around good muffler than leave it stock people! The stock muffler is hard to beat for the power that you're getting. Yes, it’s heavy, but it works well. The FMF is light and is better through the mid range, but is as good as stock on top end. The FMF has slightly more excitement out of corners (at very low rpm’s) and you’re able to shift to third gear sooner with its impressive mid range pull. The titanium FMF 4.1 muffler doesn't last long as I only got around 10 hours before the inside of the core comes apart. This is due to the muffler packing burning up and emptying out the can. If you want more durability buy a stainless aluminum system. Stay up on your muffler packing and you should be ok. The DR.D has less bottom end excitement (than the FMF), but is as good through the mid range. The top end pull is better than the FMF and is as good as stock on over-rev. The DR.D isn't as light as the FMF, but has a quieter exhaust note. The muffler packing of the DR.D will last slightly longer, but nothing beats stock for durability.
Engine: I have left it stock internally! The only thing I did to the engine was put a Hinson clutch kit for durability reasons. The stock clutch plates only lasted around 10 hours and then I had to change the plates out. The stock inner hub and basket lasted around 20 hours, so I decided to put in the Hinson clutch kit. Clutch plate life has improved to around 14 hours and I do not have to worry about baskets or inner hubs. If you are changing plates out make sure to check for grooves in the inner hub and clutch basket.
Engine Relocation: DR.D sells a engine relocation kit that moves the tilt of the engine forward 1.5mm. It doesn't sound like much, but it is really noticeable in corners. The vagueness through mid corner that the YZ450F is known for can improve with this 1.5mm tilt forward. There is more front end bite in corners with the engine relocation and I was able to feel like I have more contact patch to the ground with my front tire, which improved stability as well.
Subframe: JGR makes an adjustable subframe that can help you lower the rear of the YZ450F. The Yamaha can feel stinkbug at times on de-cel (especially when running the required 100-102mm of sag). I experimented with several settings and found out adjusting it 10mm lower than stock helped me drive into braking bumps harder without having the rear of the bike smack me in my ass. You will have to take measurements of your stock subframe before taking it off, so you are able to make the correct adjustments when putting on the JGR subframe.
Shrouds: I installed the Cycra Powerflow shrouds for the visual appearance of a thinner mid section. After measuring the stock shrouds to the Cycra shrouds I only saved 1.5mm in width. However, visually it is noticeably thinner due to the nature of the Cycra shroud shape. The Cyra Powerflow shrouds are slightly heavier than stock by over a quarter pound, but you will be gaining better throttle response with the airflow it provides. Shocking I know, but they work! The intake noise is louder, but I just like the visual appearance of the shrouds more than stock.
Offset: I keep the stock 25mm offset versus a 22mm offset for the simple fact that the Yamaha feels less harsh on braking bumps. With the 22mm (standard 2015 YZ450F version) offset on the 2017 YZ450F the Yamaha does corner slightly better through the middle of the corner. Getting to the beginning of the corner however the 25mm is much better for me as I can set up the Yamaha better to start the corner. There was not enough payoff for me on the track to switch back to the 22mm offset.
Fuel: I have been running VP’s T4E fuel in the Yamaha YZ450F and can run the same ignition mapping year round. VP Racing’s T4E is a pump fuel replacement that gives you better throttle response and bottom end pulling power. Going from the standard T4 to the T4E I could really feel the difference in pulling power coming out of corners. The fuel also will not boil as I have put motos in on hot 100 degree plus days.
Spark Plug Cap: The spark plug cap likes to pop upwards and dislodge itself from the plug. Invest in a spark plug cap holder and thank me later. If you're getting misfiring or de-cel pop more than normal check your spark plug cap immediately. It must be a problem because even the stock 2018 YZ450F comes with one now.
Gearing: I normally stayed with stock gearing (13/48), but recently have migrated to an MXA setting of 13/49. I can use third gear more in corners with the 49 tooth rear sprocket and can let the rear suspension free up more on acceleration bumps using a higher gear.
Oil: I know Yamaha says it’s ok to run synthetic oil in this bike, but I have had bad luck with synthetic oil for clutch life. I always run petroleum based oil (Maxima 10/40 Premium) and change it more often. I never had any problem with clutch fade or slippage when using petroleum based oil.
Important Settings: It is important to remember with this 2016-2017 YZ450F frame change to run no more than 102mm of sag. Do not try and incorporate your 2015 settings of 105mm or more as it simply doesn't work with this frame. You can try to run the fork 4mm up in the clamp for more front wheel grip through corners, but I wouldn't recommend going higher than 5mm. I have always had good luck with Dunlop MX3S or Michelin Starcross 5 Soft tires with this machine. Both sets have great front tire lean angle traction and that is what you need when dealing with a heavier, front end steering bike like the YZ450F.
If you have any questions please feel free to email me at firstname.lastname@example.org.