Bench sync throttle plates

[trichard310]

Hi everyone, pulled the carbs to replace some O rings (leak) and a good cleaning. Put the carbs back on the bike, and it was idling around 5000rpm. After some troubleshooting, found the problem is the throttle plates are not closing enough. I have attempted to bench sync the carbs using the #2 carb as the base. I make adjustments to nearly close the #2 carb then use a nail under the plate for gap. After I adjust the other carbs to match, I remove the nail and all the butterfly plates are in sync, but with a gap too wide. When I adjust the other carbs, it seems to move the #2 carb throttle plate reguardless of the nail holding the plate....Please advise.

[Volker_P]

Besides that a gap held open by a nail would be a huge gap for idle I do not understand why you want to use this nail at all.

Try it like that:
Turn out the black idle knob until it looses contact to the lever.
Then sync the throttle plates to be all closed without visible gap simultaneously.
Tighten the adjustment bolts and turn in the black idle knob until it gets contact to the lever.
Turn it in further stepwise and verify that all four flaps open to a very tiny gap simultaneously.
If you see differences, correct and repeat until things look fine.
This should be sufficient for nice idle and throttle response. If not, probably your carbs still have another problem.

[trichard310]

I'm using the nail in place of guitar string or drill bit, etc. Not to necessarily set a gap, just matching the plates. What I'm not understanding is when I adjust carb #1 or #3, it also adjust #2 with it. Shouldn't carb #2 be stationary when I adjust carbs #1 and #3? I've actually tried the way u suggested previously and I can't seem to get all the plates closed. The closest I can get the plates to closing is with 3 of the 4 little fuel holes exposed.

[trichard310]

Found the problem. Turns out I had two of my butterfly plates backwards.

[kerryb]

Thank you for finishing the thread so we know the solution.