Sticking throttle on 1981 CSR 650

So after following everyone's advice I cleaned out the carbs on the 1981 CSR 650 that had been sitting. Put everything back together and now I get a sticking throttle.

The engine is hard to get to idle and when it revs above say 2000 or so it will stick there for above 5-7 seconds then slowly come back down. Sometimes it won't come back down. you can rev it from idel of about 1450 to say 1800 and it won't stick. Or at least it doesn't seem to stick.

I've disconnected both throttle cables at the carbs and worked the butterfly by hand. Same issue. I'ved reved tyhe butterfly by hand and then tried to force the butterfly back down and it goes down perfectly. So the issue isn't mechanical.

I've checked for air leak by spraying all over both engine and airbox side of carbs with carb cleaner. No change in idel or smoke. I've sprayed all over the carbs and no change.

Its almost as if the slides in the carbs are sticking. Is this possible? Any ideas? I didn't fool with the air screws when I cleaned the carbs. And it didn't stick before. So thats not the issue.

Could the slides be sticking or what?

HELP>>>>>

I don't know what you did when you cleaned the carburetors but whatever you did obviously didn't get the job done. The problem could be in quite a few different areas. While it may not feel like a mechanical issue with you, it very well could be. It could also be an airleak or obstructed internal passage; especially one that is carrying fuel. Sorry I can't be more specific but if you totally disassemble the carburetors, replace all the parts that might cause an airleak... also check tensioning by the main return spring... one of those things should do the trick.

Very often, the cables may appear to be okay but might have kinks or crimps that fray the cables on the inside of the casing. I had a high idle problem that drove me crazy until I replaced the throttle cable.
Grant.

Check the easiest and most obvious things first BEFORE tearing the carbs off again:
The throttle cables as mentioned above is a good start, then check to see if any of the clamp screws (it's usually the #2 or #3 carb clamp screw) securing the carbs into the intake manifolds are in the way of the throttle linkage and causing it to bind/stick slightly.

I had the latter problem not to long ago on my ZN.
And if it went for the fact I was so tired from trying to figure it out, I would have kicked my own a$$ for missing something so simple and obvious! :blink: :laugh:

Post edited by: RetroRiceRocketRider, at: 2007/07/23 22:23

Thanks guys. I'm going to pull the carbs tonight and check the return spring. I may go ahead and try and get a stornger one fromn the hardware store. They carry all 3 type of springs there (compression, tension, and both way. However even after I took the cables off at the carbs the problem persisted. So I don't think it is the cables.

The carbs are getting air from somewhere I think. They can't be that far out of synch as I set them using a 1 mm wire (desk synch). So I will assume that synching isn't the culprit. My plan of attack is the following:

Check return spring.
Check condition of boots at intake.
Check vacumme ports on intake boots.
check to see if airscrews are loose.

I hope one of these fixes it... I will let you guys know how it goes...