RPMs don't come down after turning the accelerator back

I'm working on a 1981 XJ550. I recently got it started after 10+ years.

Current status:
- tank is off;
- aux hanging tank is hooked up;
- vacuum line is off;
- chain and sprocket is off;
- seat is off;
-mufflers are off;
-and idler is set to keep RPM <2k with choke all closed.

It will start and idle just fine. If I turn the accelerator then it revs up, good, but when I release the accelerator then it stays at that new rpm and gently creeps up.

The other day, before I tuned the idler, it was revving all other the place. Too low on the idler, I would rev it to 4k but it would not come down. Idler too high and it was just well revving too high.

I'm thinking that there is one carb that is not synced pushing the RPM up or sticks. What are your thoughts?

NB. The right side exhaust smokes abit while running and just after killing the engine. The left side does smoke.

 

If the choke is on the idle is going to continue to climb to 4K RPM. Make sure you cap off the vacuum hose or I will climb and hang. Idle must be set after bike is fully warmed up which to me is about 10 to 15 miles of riding.
You should check to make sure that the cable at the carburetors is not tight it needs a tiny bit of slack. To adjust this you go to the handlebars at the throttle grip it was a long threaded sleeve by lengthening or shortening this it changes the outer cable length and if it is too long it will pull up on the throttle shaft causing the idle to be high.

 

You will know if the throttle cable is properly adjusted as there will be 2 to 3 mm of play when you go to turn the throttle grip. It should not immediately be pulling the cable. The second issue could be the routing of the cable if it does not go down the inside of the right headlight mounting bracket down the left side of the frame over the top of the rubber fuel tank mount and over the coil, then dropping down on the left side of the wiring harness to the carburetors, the cable can bind. Cable also needs to be properly lubed when installed and lubed on a regular basis or it can stick. New cables do not come lubed

 

After the above is checked you want to start looking for vacuum leaks such as the vacuum hose to the petcock not being plugged with the golf tee. Vacuum leaks will occur at the carb manifold boots could be cracked or loose. Vacuum leaks can occur at the throttle shaft seals. You can check this with an unlit propane torch and see if your RPMs climb. Or you can use carb cleaner in Sprint in these areas and see if the RPMs climb I use the card cleaner last as I don't like spraying flammable liquids on my motor.

 

When you say "choke is on", you mean that the choke lever on the handle is to the left opening up for more fuel, right?

I'll do that.

Good to know. I'm planning on revisiting the idler once I have everything back on the bike.

The accelerator cable?

 

I don't think there is tension in the accelerator cable. Lubing it is on the list once I get the bike up and running.

 

Yes my choke on I mean whatever is swung to the left using the enrichment circuit to put more fuel into the carburetors
Yes the throttle cable accelerator cable the cable that goes from the right hand twist grip down to the carburetor and connects to the little pigtail cable and pulls up on the throttle shafts to make it accelerate. You should leave the throttle cable now to eliminate it as a problem you can either do that with a can of spray in the little tube that clamps on the cable or you secure a plastic bag to the throttle cable end put some light oil in it or cable lube and you can let it hang overnight and gravity will do the job just move the cable in and out a few times and that will help get the oil going down the tube I prefer cable lube as oil may affect the inside lining of some cables

 

All the boots are cracked to some degree. Buying new boots is on the list.

 

you can clean boots with carb cleaner and then coat them with black fuel resistant rtv also can go the extra step and wrap an inner tube around them for an acceptable repair