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· Registered
3,761 Posts
Sounds like you have 1 of 3 possible problems.

Providing neither of the throttle cables are sticking and BOTH throttle cables are hooked up:

A. You have a pinched breather line on the carb(s). **Most likely cause**

B. You have a burr or dry slide inside the carb and it's sticking.

C. You have a weak spring in the carb that keeps the slides pushed down when not under throttle.

· Registered
3,761 Posts
slickster said:
a dirty air cleaner won't cause your problem, neither will a sticking carb slide, it'll just make it run very rich, the throttle plates control rpm....
Actually, a sticking slide will cause RPM to increase.

When you choke the bike, the RPM increase and the throttle blades don't move.
A sticking slide will do the same thing as a open en-richening valve.

The throttle plates do not control the RPM solely, either.
Throttle plates control the air flow or more correctly, venturi pressure.
The slides control fuel flow and they both work together to regulate RPM.

· Registered
3,761 Posts
mde8965 said:
This certainly sounds to me (like I know anything) like it is plausible. Since the bike has only 10k miles and I don't know the maintenance history, the carbs probably are gummed up to some extent. I figured I would change out the air cleaner, adjust the valves, replace the plugs, clean the fuel screen and replace the fuel filter, and run some seafoam in the gas (already put that in yesterday). Then if the problem still exists, it HAS to be the carbs (I'm guessing) or a vacuum leak. As far as the carb do you check them to see if they are sticking? Can I do this with the tank off and the carbs still on the bike or do I have to remove them? If they have to be removed, I will probably clean them and replace all the seals while I am at it...but would rather not if I can solve my problem without removing them. Any chance the seafoam will help unstick them?

If I have to remove them, should I sync them too? I do not have a mamometer (sp?)...can I take them off and take them to a shop for that?

Are there any common areas to look for vacuum leaks?

THANKS everyone for all the help and opinions!!
SeaFoam generally won't help a sticking slide, unless it's sticking at the needle, where it goes in to the needle jet.
If the slide itself is sticking, you have to remove the diaphram cover
to get them out.
If it's the needle sticking, SeaFoam could possibly help.

You're doing all the right things in doing possibly overlooked maintenance.

A vacuum leak can occur anywhere there is a rubber vacuum line connected.
Don't just look at where they are connected though, pinholes in vacuum lines also are source.
They can also occur at the isolation boots that hold the carbs to the head.
If they have a lot of age on them, it wouldn't hurt to replace those also.
They will get dry and can leak there.

There are two ways to check to see if the slides are sticking.
Both ways require having the carbs off.
With them off, you can open the throttle blades and very gently lift
the slide with your finger. It should move up in the bore freely and return
The other way is to very softly blow and suck in the vent tube.
This will cause the slide to move and fall. Again, it should do so freely.

It is definately a good idea to resync the carbs after you've removed them.
It's not something you can take off and take to the dealer to get done.
It has to be done on the engine that the carbs are on.
The reason is that manifold vacuum is not exactly the same across all
engines. You cannot sync your carbs with your two cylinders
and then take those carbs and move them to a different bike.
The health and efficiency of each cylinder detmine how the carbs sync.
When you synch the carbs, you are sync'ing them so they will pass
the same amount of air between two cylinders.

Talk to MarkC or cbjr0256. I believe both of them have successfully made
manometers out of clear tubing.
Either one of them can direct you or tell you how to make one that
you can set your carbs with.
I have a set of Honda 4 gauge units that I use, but if I didn't, I sure
wouldn't hesitate to make one like they did.
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