Calling All BK Moder's Have Question

:) Can someone explain the Timing from the Pump screw to the BK mod itself. I have had to make no adjustment to the Accel, but was able to adjust down the duration from the Mod.

What purpose is the Pump screw ?

Why do Butter Flies ?

Why is All Green

Also When is Helen Ready ?


Seriuos Though I find no refreance in the Manuals, and true to form the Dealerships are Duhh Wudya mean , Geez I would be better off asking Clinton to tell the truth ?

The factory screw is a timing screw. The BK mod screw is a duration screw. The factory screw allows you to adjust when the squirt begins relative to the throttle position. The earlier posts on this topic agree that timing the squirt to just miss the slide is best but I have yet to find the sweet spot. I've still got a bog at the bottom, although not as severe as before the mod.

Hope this helps.


Just curious but is your bog noticable during regular riding?

Originally posted by bbeakley:

I've still got a bog at the bottom, although not as severe as before the mod.


>Did you increase your pilot jet size after the BK mod?? If not, that may be a part of your problem.

>Is the bog while on the stand or when riding?? Any bog on the stand doesn't count. It has to be tested while riding.

>This is the jetting I have come up with after hours of playing around: 45 pilot, one leaner on the needle and 165 main. I do use race gas so I can be jetted a bit leaner than if using pump gas.


:) Thanks for the info, I never had to touch the timing, The Bike responded perfectly by shutting down the duration. I could probably tweak it some but why fool with somethig that is working as I like.

The BK took the Bottom ..... Ok nows a good time to accel (Bogg) completely away and the beast rips out of the corners...

Would love to have Tim Ferrys Free Wheeling Clutch though

I my pump timing screw with the bike on the stand running. I basically ripped the throttle open, turned the screw BOTH directions until I had my best throttle responce. You really shouldnt end up with any kind of a lean/rich condition with this adjustment because your not changing the mix as much as when it hits. My bike doesnt bog anywhere, not on the stand, definitely not on the track. My jetting is Main 168 pilot 45 stock needle 1 notch richer, but I have a Thunder Alley exhaust too so, if your pipe is stock, you could leave the needle but Id still go up on the main and pilot and dial the pilot with the screw.

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