High idle???

[Drumagician]

I just put the bike back together after changing plug wires and caps, replacing valve shims, and replacing the carb butterfly valve seals. My bike idles at 2000 rpm after syncing for some reason (was 1100 rpm before sync). The idle adjustment screw is backed all the way out; the throttle cable is 100% not causing the issue. Before installing the carbs on the bike, all butterfly valves looked completely closed and working properly. Could there be any other reason for high idle other than a butterfly valve issue?

[motoman]

Check your vacuum caps or lack of that was just off to re-sync.

[cywelchjr]

And disconnect the throttle cable from the carbs and see if the idle stays high, more than one person has found that the cable WAS holding the idle up even though they were sure it wasn't. If it won't go down with the adjustment, something is wrong, and the most likely is either a bad sync or something holding the throttles open, and the most likely item for that is the cable.

[ManagerMike]

Based on your info, I vote for the 'bad sync' remote diagnosis; one of the carb throttle valves is bottomed out and holding the other three open off of the idle stop screw.
Made that mistake myself as I was educating myself how to improperly sync carbs. I believe I have since educated myself how to do it correctly.

[XS1100_OEM4ME]

Air flow

If you dont have too much air flow your idle will not be to high (regardless of gas flow) you have something not letting the butterflys close right, you said you replaced the butterfly seals, I would check there first. If you take the carbs back off and hold them up to a bright light, I am guessing you will see where the butterfly vavles are not closing all the way when adj to full close on idle screw. Dont know what you did when changing the seats but I am pretty sure this is your problem

[Drumagician]

Yes, after taking carbs off and holding to a light, there was gap evident that I couldn't see without the light. I needed to reposition the butterfly valves and all is good now. Thanks all!!

[XS1100_OEM4ME]

Fyi

Yes, after taking carbs off and holding to a light, there was gap evident that I couldn't see without the light. I needed to reposition the butterfly valves and all is good now. Thanks all!!

Just FYI, if you moved/adjusted the butterflys I am guessing you loosened or removed the screws, when you get them where you want them they "NEED" locktight of some kind on the screws. The factory stamped the ends to keep them from comming lose and going down the intake and tearing up cyl/valves Just a heads up, good luck with your bike

[Ken Talbot]

My guess is that one of the hose clamps holding #2 or #3 carb manifold to the head is twisted around a bit so it is interfering with movement of the throttle mechanism. It has happened before.

[cywelchjr]

My guess is that one of the hose clamps holding #2 or #3 carb manifold to the head is twisted around a bit so it is interfering with movement of the throttle mechanism. It has happened before.

Very good idea. That is indeed something to look for, as it is one of the things that can cause the reported problem.