Boyesen Accelerator Pump Cover?

Do you mean to tell me that there are 3 different diaphrams for the accelerator pump? I own a 2002 YZ426F, I installed the P-38 Lighting cover from Factory R&D, it seemed to help allot at first, but I feel like the sputter is coming back when I snap the throttle real quick! I would love to eliminate this sputter, I'm running a 165 main and a 45 pilot with a stock needle at stock position, pilot turned out 3/8, any tips? Buy the way, I just installed a Protaper Twister throttle tube with the needle bearing in it, what an amazing mod! I have so much throttle control now, worth the $80.00 big time!

its inside the float bowl not the carb. when the bowl is off look down into it;brass thingy with a screwdriver slot :naughty:

Yep, I made that mistake first time I went looking for the leak jet. Its in the part you take off (the bowl) of the carb below (if I recall correctly) the accelerator pump.

I own a 2002 YZ426F, I installed the P-38 Lighting cover from Factory R&D, it seemed to help allot at first, but I feel like the sputter is coming back when I snap the throttle real quick!

Keep in mind that diaphrams wear out and they recommend replacing them at least every year! I bought the Boyesen AP cover but after reading the instructions found that they recommend replacing the diaphram, O ring and D ring if more than a year old. So now I wait on that order which by the way was 50% less through TT Store than anywere else. About $20 total not including the Boyesen cover.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now