something funny on timing advance mechanism?

Hi all, first off, this in for my 77 kz650 b.
I have had issues with the rpm's not returning back to idle normally.
If I rev it up it wont drop back down to normal idle. (stays around 3K) If I put into gear and release the clutch a little to put a load on the engine, it will drop back to normal idle.
Ive seen several posts here with similar situations, and common idea is an air leak.
I agree with this, and have done everything, (new carb mounts, new vacuum port plugs, new clamps on carb mounts, and nice soft boots to airbox) I am fairly certain, that there is no air leak.

So I started to look at the timing advance mechanism. It seems clean and moves freely. But there is something funny.
Just inside the tips of the moving arms (right where they contact the center shaft) there seems to be some sort of rubbery material. (see pic) It just looks like some gunk in there, but is actually some rubbery material that is bonded to the moving arm. It is exactly the same on both arms.
Should this stuff be there? Should I scrap it out?
It seems like this will effect my timing. as the thing gets hot, that stuff will surely soften up.
Has anyone else seen this kind of material on their mechanism?
All ideas are appreciated.

Thanks
MJ

Sorry I meant, "scrape" it out.


MJ

Those are supposed to be there on certain models, and they dont have a large effect on the timing at all.

If you can turn the rotor clockwise until it stops, and it snaps back to the home position, everything is fine with the advancer.

Your problem could also be incorrectly tuned mixture screws.

GL.

They would only be a problem if they were NOT there. The advance would have too many degrees.

Thanks guys, glad that I dindt scrape them out!
Other than that the mechanism seems fine.

I looks like back to the carb tuning.

Thanks again.

MJ

mjkawa wrote:

...77 kz650 b...issues with the rpm's not returning back to idle normally. If I rev it up it wont drop back down to normal idle. (stays around 3K) If I put into gear and release the clutch a little to put a load on the engine, it will drop back to normal idle. Ive seen several posts here with similar situations, and common idea is an air leak.
I agree with this, and have done everything, (new carb mounts, new vacuum port plugs, new clamps on carb mounts, and nice soft boots to airbox) I am fairly certain, that there is no air leak....

Couple of questions ---

Carbs synced?

Mikuni manual slide carbs?

Manual petcock?

---

Sometimes easier to determine air leak by clouding the area with propane gas (unlit) instead of WD40 while listening for any change in rpm due to ingestion of propane.

Might be air leak due to a choke plunger failing to fully close.

If not already done, would use a timing light to assure correct ignition timing.

Could also be just a dirty pilot circuit.

Good Fortune!