BK Mod. squirt timing screw: 1/8 turn=big difference

I was trying some different jetting today and thought I'd re-check the squirt duration and timing screw positions from the BK mod I did 6 months ago. I turned the squirt timing screw a 1/4 turn each way, and then fine tuned to 1/8 turn final adjustments. What a difference!

For those of you who did the BK mod and just set the squirt timing screw by eye (fuel stream just misses the slide), if you haven't done so already, you need to go back and fine tune it while riding the bike. Make a couple of 1/8 turns each way from your current setting, and note what the difference is when riding. You can definitely tell when it's getting too much squirt (rich), and when it's not getting enough. When it's just right, you'll notice that the bike is much more crisp and responsive on the low end, and if it's like mine, the front tire will want to shoot skyward when whacking the throttle open! Just remember that if you make any adjustments to the timing screw, you may need to go back and tweak the squirt duration screw.

Ditto. I’ve done this mod to four or five bikes and rode them all, and I ended up increasing the delay, to good results, on all of them.

¼ turn is too much change. Try 1/8 turn increments, it makes an easily noticeable difference.

Like all other carb fiddling make sure the bike is fully warmed up before you do your testing.


I have spent a lot of time messing with the timing screw, and I believe it makes a HUGE difference. I also noticed that my bike is much more finicky when it comes to jetting. Before I did the BK mod, the bike ran good anywhere I took it. No adjusting required when going from 100 feet to 6000 feet. After the mod, at least a clip adjustment if not a main jet change is required.

I guess that is the price to pay for a major improvement.

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