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We have just over 25 hours on the 2021 KX250 and so far we really love this machine. The KX250 is one of our favorite 250F’s to ride due to the work the Kawasaki R&D engineers made to the 2021 model . Although there will be a follow up article soon with some ECU and engine mods we thought why not throw up our initial top 5 mods that we have done to our worn in 2021 KX250. These mods below have improved the engine and chassis feel even more and as given us more confidence in the machine.
1. Pro Circuit Ti-6 Muffler System: Normally I DO NOT get more bottom end with a PC system (versus stock) on any brand of bike, but I was surprised that I got a little extra bottom end pulling power out of the PC system. RPM response is a little softer than the stock system, but when opening up the throttle out of corners the KX250 with the PC system pulls harder than the stocker. Mid range is where you will feel the meat of this power. When accelerating out of the corner and shifting to third, the KX250 doesn’t have that “empty” feeling that the stock muffler has at times when the track is tilled deep. The PC system keeps pulling once the KX250 is shifted into third gear and continues to pull harder into the top end of the machine. Over-rev is as good as stock and I didn’t notice any loss of over-rev when swapping the two mufflers back and forth.
The only real negative I have found from the PC system is I wish it would have a little more low end RPM response. Like I mentioned that stock muffler has a great initial touch of throttle which can make the bike feel a little lighter when hopping over bumps or popping out of blown out berms. The PC system pulls better out of corners, but is just a smoother initial touch (AKA, low end RPM response). If you want more low end RPM response and could stand to lose some pulling power then take the screen out of the Ti-6. Doing this will give you more low end RPM response, but will hurt some mid range.
2. ECU Re-Mapping: If you want more pulling power as well as more top end install the “Chavez Map” with your Pro Circuit Ti-6 or any other muffler system and thank me later. We used Kawasaki’s Calibration Tool to tweak the fuel and ignition timing in order to try and get some more pulling power out of the 2021 KX250. The map you see above will get you some extra torque when exiting corners while maintaining the excellent mid-top end power that the 2020 comes with. Use the stock green coupler with this ECU setting…
3. Gearing: 13/50 gearing is just fine for the Intermediate to Pro level rider with either the green or white coupler. If you’re a heavier rider that is lazier in corners you can try a 13/51 gearing to help you get back into the meat of the power sooner. We suggest using the green coupler with our preferred ECU setting with the 13/51 gearing however. This will ensure that mid-top end pulling power doesn’t fall off too soon.
4. 110 Rear Tire: A few manufacturers still like to run a 100/90-19 rear tires because it’s lighter. However, the 110/90-19 rear tire offers more traction and has better comfort on square edge, hard pack areas of the track. The 110 doesn’t weigh the 2020 KX250 down in deeper soil that much and in fact, I see no negative on the track to going up a size on the rear. The Kawasaki has plenty of mid-top end to carry the small amount of extra weight the 110 carries. You will get more lean angle bite coming out of corners as well as increased stability with the 110. The 110 will fit on your 1.85 rear rim so don’t worry about your standard current rim size with the 110 rear tire sizing. I am currently running a 110/90-19 Dunlop MX33 on the rear of the KX250 with good results in soft to intermediate terrain.
5. Pro Taper EVO Handlebar:
The stock Renthal Fatbar 839 handlebar is a great bend, but for me it’s still too stiff. If you’re looking to get less vibration and more flex out of your 2021 KX250 look into a Pro Taper SX Race bend as it’s only a couple millimeters lower than the Renthal 839 bend in height.
Honorable Mention: Ride Engineering makes awesome one piece rubber mounted bar mounts that DO NOT twist like the stock ones have/can. The stock bar mounts are soft so going to these 100.00 bar mounts ensured my handlers do not twist in my clamps. I like the stock triple clamp for this machine so I left stock triple clamps on.
Change oil every 2.5 engine hours with Blud Racing Pro Series 10/40
Oil filter every other oil change
New Chain guide/slider at hour 15
Purchase a new throttle tube when getting new grips. (Stock grips are vulcanized to the tube)
New DID ERT3 gold chain at 10 hours
Running VP T4 race fuel
Using Dunlop MX3S front/33 rear combo at 13.5/12.5 PSI
Acerbis Plastic Kit at 20 hours
Throttle Jockey Team Green Graphics Kit