A must for all four strokes using the Keihin FCR carb.
To get the best throttle response from your four stroke engine you must properly adjust the low speed fuel mixture screw. Due to the difficulty of adjusting the stock screw Pro-Tec has designed an extended fuel mixture screw that can be adjusted by hand without the use of any tools.
Manufactured to the exact tolerances of the stock screw with a built in thumb wheel for easy adjustments.
Will fit all YZ/WR 250F, 400F, 426F, 450F, CRF450R, KTM450, KTM520 and YFZ450.