Revs remain high, what's up?

[pasteurized]

Finally got my GS750's carbs all put back together from being cleaned and rebuilt (screw you, I'll do what I want, landlord!! :-) ). The setup of the carbs is essentially the same as before being cleaned except for a little difference in pilot screw adjustment. I know they are way off as far as sync goes, but other than that they are good to go. The problem is that when revving the engine in or out of gear, the rpms stay high for a few seconds, and then slowly, gradually come down. I took it for a test ride around a few blocks and I have to be very slow and deliberate with my shifts. If I shift like normal, once I pull in the clutch the rpms will shoot up in between shifts and it makes for a really herky jerky shift. Before rebuilding the carbs I didn't have this problem, although it did seem like it took a little longer than it should for the motor to rev down but I was convinced that was a tuning issue as it has never been tuned correctly. The carb boots are questionable but I did the old spray water/carb cleaner near the boots trick and I couldn't notice any difference. I can't imagine that a sync would fix the problem, and I am not sure about the boots. What else could it be? I have a Morgan CarbTune but I'd have to ride it elsewhere (like to a buddy's place) to do that. I will be ordering new carb boots as well, but I'd like any input that you can give. The throttle cables are working like they should be, valves are adjusted, etc.

Thanks!

[Redman]

Classic symptoms of air leak at intake boots.

Did you do the "spray test" right where the boots between carbs and head mate up agains the head? There are orings in there.

[pasteurized]

Forgot to mention, I replaced the O-Rings last year and I checked them while I had everything apart last week. They still looked good as new.

[gotjeepzj]

On mine the return cable was catching.

[Nessism]

Sounds like an air leak to me.

[mark]

I can't imagine that a sync would fix the problem

It might. With VM carbs if the synch is way off you can get your bike to rev. through the roof. Ask me how I know.

[chef1366]

Check your slides.

[pasteurized]

I just ordered 4 new intake boots and I have 4 brand new O-rings, so once the boots come in I will install them and do a good sync on the carbs. I guess I will have to see where I am at that point. Hopefully both of those things take care of the problem!

If anyone else has any ideas of what could cause this problem, feel free to post it but I am *HOPING* that this does the job. It was really nice to be able to ride the bike around a little today, first time since November! Even if it wasn't running like it should be :-/

[tconroy]

That will do the trick.Air leaks are often hard to fine and when the bike warms up it gets worse.The boots will seperate from the metal flanges and you cannot detect it untill it warms up to temp.You wont believe the difference in the boots.They will be soft and flexible instead of hard as a rock.It also make it easier to pull the carbs on and off.

[Steve]

While you are waiting for the new boots and o-rings, you have the carbs off already, so do a bench sync to at least get them in the ballpark.


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[pasteurized]

Thanks tconroy, I am thinking the same thing. I hope it takes care of the problem!

Steve, I will do that. I'll have to do a search and come up with a bench sync guideline, but the basic idea is to get all the slides open the same distance when throttle is closed, and then basically do the same thing when the throttle is completely open, right?

[Bustinjustin2k]

been there my friend

I fought with that forever, I removed the carbs so many times I had dreams about it. Eventually I spent 5 bucks on a massive box of O rings, followed the directions on this site how to compleatly disassemble your carbs, got a dunk tank, removed EVERYTHING from the carb, new o rings and bamn better then ever. Im not talking the O rings in the boot, Im talking about every O ring inside the carb itself. Good luck bro.

[tconroy]

Thanks tconroy, I am thinking the same thing. I hope it takes care of the problem!

Steve, I will do that. I'll have to do a search and come up with a bench sync guideline, but the basic idea is to get all the slides open the same distance when throttle is closed, and then basically do the same thing when the throttle is completely open, right?

That's right but go by your slide on the 3rd carb cause you cannot adjust it.Set all the others to it.You can get really close just by looking at eye level then use your carb sticks

[pvtschultz]

How did it ever work out for you????