Carb sync

Looking for some mechanical advice or sharing your own tales of the workshop wonder.

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peckafransson
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Posts: 13
Joined: Tue Nov 30, 1999 12:00 am


I have some problems to syncronize my carbs. It seems that the three set screws affect each other when turning them? How should it be done? The fourth carb is the base carb but the vacuum will change when turning other set screws??
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jamiedaugherty
Member
Posts: 163
Joined: Tue Nov 30, 1999 12:00 am


When adjusting one of the sync screws you should not see any change in the other carbs. While turning it you can sometimes push on the linkage such that the gauge moves, but once you stop the other three should come back to where they started.

Something else to consider is that the idle speed can/does change while sync'ing the carbs. This can affect the reading of the #4 carb too. Don't be concerned about the actual reading but rather that all four are together.

I suppose I should ask: you are adjusting them with the airbox and everything assembled, correct? I've seen guys try to adjust the sync screws from above with the airbox base plate removed. Don't do that.
peckafransson
Member
Posts: 13
Joined: Tue Nov 30, 1999 12:00 am


Thank you Jamie, I do have all parts assembled....
I will do a new attempt this coming weekend and see what the result will be. I might have some vacuumleak which I will check by spraying startergas around the rubbers.
It is a little akward to adjust the three screws as they are situated underneath and very hard to get to....
I have now purchased a long 90 degree screwdriver with a 7 mm socket. I hope this will help me through this task :)
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jamiedaugherty
Member
Posts: 163
Joined: Tue Nov 30, 1999 12:00 am


Yeah, a 90° screwdriver is a must for adjusting the carb sync. I think you'll have a lot better luck using that!
peckafransson
Member
Posts: 13
Joined: Tue Nov 30, 1999 12:00 am


I did not receive my 90 degree screwdriver to have a go last weekend.
New try next weekend...Another thing Jamie, I have set the butterflies according to the book , aligning the very small holes on all four carbs when the carbs were out the frame.
Now when I have been fiddling around with the setscrews in situ, how could I get back the initial setting without removing the carbs? It is not possible to see the small holes from the breather side.
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jamiedaugherty
Member
Posts: 163
Joined: Tue Nov 30, 1999 12:00 am


No need to bother trying to get back to the initial setting. That's only to get the engine running, using sych gauges is the only way to get them set correctly.
peckafransson
Member
Posts: 13
Joined: Tue Nov 30, 1999 12:00 am


Well, at last I managed to sync my carbs successfully! The main problem was that two inlet rubbers were not sealing properly. I must say they are somewhat troublesome to get seated correct. :evil: My 90 degree wrench from, http://www.carbtune.com/, with a modified 7 mm socket worked fine. :D
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