I'd like to think I know what I am doing, but maybe not?

After dealing with the garage find I have, 81 650 Maxium, I am having one giant issue getting it to run correctly. The bike was parked for around 6 years. Of course the tank, carbs and everything else were a mess. Removed and cleaned the carbs. Everything went back together great! Took it for a short ride. After getting back home, thought that 9 miles were not enough, fired it back up and took off. Got about another mile away and the revs started racing, 2500 then 3500 and upward. Took the carbs off, AGAIN! looked for crap that might have shaken loose, found a few things and the reassembled and reinstalled.
What I've tried and found:

Syncing the cabs. 1 and 2 are good, 3 and 4 are good. Once I start to sync the 2 sets, I get the crazy runaway idle again. When I remove the vacuum tube from #2, the idle settles down, to near stalling. I have also noticed that it seems the spring on the main throttle is pretty weak. Doesn't seem to want to return to a full closed position. Thought that the cable might be bound up, verified that it is not.....

Checked the float levels with the clear tubing method. All seem to be close to where they should be. Have also adjusted the main idle screw, of course if varies with the sync.

ANY and all help would be fantastic.
Thanks in advance
Glen

 

I wish I could help ya, but it's all
Chinese Greek to me.

 

racing usually means an air leak. double check that the boots to the carbs are all installed correctly.

check the throttle cable is routed correctly.

also - might wanna double check that your idle isn't set too high - it takes a very long time to get the engine warmed up enough to set the idle correctly.

 

The symptoms read just like an air leak somewhere in th carbs
most likely th throttle shaft seals 8 of need replacing..or loose/cracked intake boots or th seal on th boot to th head. A complete carb overhaul is standard procedure for a bike thats been sitting for a long time.

 

To get revving-up to 3500 revs.
You need:
Throttles open + Air

Back-off on the Idle Rod to make sure the Throttles shut.
Polish the Bores
Make sure the Diaphragm Pistons rise and fall without any interference.

Test for AIR Leaks.
Spray Carb Cleaner on the Manifolds and Carbs and see it the Bike revs higher.

L@@K at where the Carbs enter the Manifolds and see if the Clamps are within the groove where thy belong.
If they aren't in the grooved area they cut the Manifold and cause a leak.

 

Thanks for the advice Gents.......Tomorrow is a new day and another shot at it. I did narrow it down a little farther.

Hooked up the Sync tool again. When I remove the vacuum line from the intake side of carb 2, the idle settles down. Hook up the gauges again, revs race up. Thought it might be the gauge, tried the same line on carb 1, normal results followed. I did use Permatex Spray and Seal on the boots (head side) intake side are almost perfect. Checked for false air entering (unlit propane torch) no rev increase.
I was REALLY trying to avoid taking the carbs off once again, however, looks like a fun filled Sunday!

Thanks again.