BK Mod

[Hot4Teacher]

I have a '99 yz400f. I hear alot of prople doing a BK mod on the newer thumpers. I was told that the mod can't be done on the 99 because of the different carb. Is this true? or is it just a little different technique on the older yz's? Any help would be greatly appreciated. Thanks.

 

[Senior KX Rider]

moved

 

[endosports]

Different carb all together... I haven't looked at it closely on the 400 but i believe that it is not possible.
I have done this to my 01 426, but it is a different carb all together. Can't tell you how much this mod has helped me out.

 

[Shawn Mc]

You can acheive the same thing with a p-38. Its an acclerator pump housing that replaces the stock one. I wish I could remember the Manufacturer. You can get it at MR.X i think.

 

[stormer94]

P38 info

http://www.mxsouth.com/perp38lit.htm

I just got mine, haven't put it on yet though.

 

[Hick]

You can buy an RC Wheel Collar and install it on the pump actuating rod for the same effect.

Click HERE to get the wheel collar, apparently the 3/32" collar fits best. The idea is the collar fits on the rod, acting as a stop to limit the pump stroke (ala infamous BK mod). Cheaper than the P-38 and infinitely adjustable.

I have not tried this myself, but plan on using my friends 520 EXC as a guinea pig. At any rate a few guys at Thumpertalk have tried this with some success.

Hope this helps.

 

[Hot4Teacher]

Thanks guys for all the information. I really appreciate it.

 

[Shawn Mc]

Hick has the set up. 89 cents verses 103 bucks, even an over paid freestyler can figure that out!