High Idle/ Reving High

I recently cleaned the carbs on my bike and just installed them back in. I started it up today and it turned over fine. But right when it turns over the thing starts revving like crazy! The idle speed is up in the red zone on rpms. So I shut it off immediately. I dont really know what to do here to fix it. Any suggestions?

 

Double check that nothing is binding the throttle cable. Check for air leaks.
For an engine to rev up it has to get air. What you have to do is find out
where it's coming from.

 

happened to me once. throttle cable was too tight. try loosening it up a bit. also check your idle adjustment screw.

 

Theres no obvious air leaks anywhere. I dont think the throttle cable would be a problem with the bike idling but ill give it a try. I tryed turning the idle adjustment screw out (which decreases idle speed) That just made it harder to start. It sputtered a couple times but then died.

Maybe I messed up somewhere when I was cleaning the carb. What else could it be?

 

are you sure when you put the tank on that you didnt pinch the throttle cable. i clearned carbs once put everthing back together and didnt realize that the tank was right on top of the cable. turned the bike on and it reved so high i thought the bike was going to 'splode.

just a thought...how about try disconnecting the throttle cable and see if at least the bike starts up and idles. then you know its not the cable.

 

Positive its not the throttle cable. This is getting ridiculous I don't know what to do.

 

Remove the Carb Linkage Connection from being captured beneath the Cylinder Head.

Don't PRY it and BREAK it!!!
Move the Carbs.

Everybody inn the world has made this Rookie mistake but won't admit it.

Me ... included.

 

trying to picture what your talking about rick. could you elaborate.

 

The attachment, on the Carb Linkage, where the Throttle Cable attaches to the Carb Rack often gets tucked-up under the Head and forces the Throttles open.

You'll have a run-away rpm's in that situation. Because even though the Throttle Grip is Closed the Butterfly's are almost wide open. It happens when you put the rack back on without securing the attachment to not be jammed-up under the rear of the Cylinder Head.

You have to Pull the Rack back and free-up the Linkage. Trying to pry that attachment loose will often break it off or bend the linkages keeping the Butterfly's Open.

Once freed, the linkages can act on the Return Spring and the rev's will be normal.

This happens to those who pull-off a rack of Carbs so frequently there ought to be a caution written in the how-to section to avoid it!

 

I got the bike running good now. It was just the throttle cable to taught.

 

Don't fib.

I know what you did.

Been dare; done datt!!

 

I just bought an '81 XJ750...PO says that the motor is an '87.... idle was fine when I checked it, then I rode 50 km down the rd and it revved at about 3500rpm....I pulled over let it cool...all good...heats up again...revs go up .....

So disappointed to pick up a bike and have that happen just down the rd.

Can anyone help me on this one.

Cheers
Sammy

 

Can anyone help me on this one.

maybe the P.O.

 

Hmmmm......yes I'm going to try that...however I think the PO is a F&*%g sly dog that has about as much scruples as John Howard (Our previous P.M).

I'm hoping someone here can give me some help based on their previous experience.

 

The first thing to do is check for air leaks.
Air leaks will cause the bike to run the idle up and also run lean causing the bike to heat-up.

Another factor that cannot be ignored is: Age! Passage of time. Lots of time.

All that time has probably caused some oxidation to occur in the Piston Bores of the Carbs Diaphragm (Slides) Chambers.
If there is oxidation on the Bores the Diaphragm Pistons do not Rise and Fall as they should and the Mixtures are all over the place making the Bike run crazy.
Sometimes OK
Sometimes not so good.
Sometimes not at all.

Please search the Forums for:
Your Bike Needs to Go Clunk
Clunk Test

Perform a Clunk Test and when your Bike passes the Clunk Test you'll be feeling better.

 

Hmmmm......yes I'm going to try that...however I think the PO is a F&*%g sly dog that has about as much scruples as John Howard (Our previous P.M).

So you think this lieing dog is better, he'll have you all in the dole queue in short time.