BK mod for 1998/1999

what is this mod for the 1999 400? searched for that thread but no longer exists on server..........

I hear that there is 2 ways to do this.

1. Drill and tap the bottom of the acelerator pump and insert a set screw to limit the travel of the pump.

2. The other is to install a locking coller on the pump shaft (brass looking thingy) to limit the travel. You can get these collers at Radio controlled car hobby shops.

Mine is still stock. I was looking at www.powersportspro.com and they have listed diferant acelerator pump diaphrams for our bikes. Never tried to order them though. This is how we were supposed to tune the pump on the older bikes.

Yep I just looked there are 4 diff diaphrams listed for the 400.

5JG-14940-05-00 $16.99

5JG-14940-07-00 $16.99

5JG-14940-08-00 $26.99

5JG-14940-09-00 $26.99

Not sure what one is the stocker though.

what is this mod for the 1999 400? searched for that thread but no longer exists on server..........

The BK mod wilnot work on the 400's ony the 426 and 450

for the 400 you need the Factory R&D P-38 Lightning

do a search for Factory R&D P-38 Lightning in the 426 section you will learn about it.

Here is a link to the mod

GBmod Explained Thanks Garrett

wait a secong isnt there the Taffy mod, it has to do with putting a collar on the accel pump rod i think to shortin the duration.

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