Bonneville America Forums Forums Technical Forums Performance Mods Choke question

I have completed the AI/snorkle removal and air box drilling. I have yet to drill out the cap on the carb to make the gas adjustment. Why could I not run the choke at say 1/4 open? Wouldn't this have the same effect?

Are you asking about removing the cap that covers the mixture screw on some of the bikes? It's not on all of the years so you might not have a cap covering your mix adjustment. Using the screw instead of the choke gives precise results.

If you mean drilling the slide DO NOT drill the chrome top cap on the carb!! Drilling the slide on earlier models made the slide open faster causing fast response.

As for the mixture the choke won't give you the same effect and just plain isn't the right way to do it. Adjusting the pilot screws isn't hard to do.

I just bought the replacement thumb screws from Brent (NewSpeedmaster.com). I wish I had done this before. I never could get a solid feeling using the D-tool and the left carb was really hard to adjust. It is very easy to replace the thumb screws for the factory ones. The best part is that it is so easy to tell where they are and exactly how much you have turned them out.

I'd hightly recommend anyone getting them who wants to know how your carb screws are set and who wants to be able to easily change them. If I want to try a change, it's very easy and I know I can put it back exactly like before.

Thanks. It is a 2002 so I believe the mixure screw is capped and no D tool required. I will get around to making that adjustment. I was just curious why opening the choke would not have the same effect.

If you could do it perfect every time it probably would but you can't.

The problem with using the choke to adjust the idle mixture is that the choke stays the same throughout the operating range of the engine. The way the air bleed on the idle jet is setup, the idle port stops adding fuel when the slide starts opening, then it comes back on when you get up into the wide open throttle high speed heavy load region.
If you have a right angle drive tool, (a small air ratchet works nicely) you can drive a small self drilling sheet metal screw part way into the cap. Then grab the screw with pliers and pop out the cap.

Lacking special equipment to actually measure the mixture, you can get really close to ideal by adjusting for best idle speed.

Due to variations in tolerances and such, there can easily be as much as 3/4 turn difference from one side to the other, so don't worry so much about turn counts except to get to a workable starting point when replacing or rebuilding carbs.

Good explanation. Hope to get around to this this weekend.
Thanks.

Best way to adjust mixture screws is to disconnect the right plug wire to adjust the left cyl. and vise versa. Turn the screw in until it runs rough then out until it runs rough then split the difference. You will need to turn the idle up some to do this or it won't idle on 1 cyl. at a time. Don't let it run too long on 1 cyl. , just long enough to do the adjustment.

Just cant justify $40 for 2 thumbscrews....maybe Santa is listening...