1966 R68S - sticking advance?

[pkboxer]

Bike is a friends '66 R69S. It sits a lot, last time, maybe 3 months.

It ran fine then. Now it doens't want to rev up when cold.

Then when it's warm, it has a high idle.

I'm not familiar with the /2 but am thinking that the 69S has an automatic advance and this may be sticking.

Any other thoughts or do I need to pry more information out of him first?

[Kurt in S.A.]

If it's a sticking advance, you can test that the next time it happens. Pull in the clutch, drop it into gear, hold plenty of brake, and slowly let the clutch out to just engage the motor. The speed should come down, but don't kill the engine. Without touch the throttle, does the speed stay down now? If yes, then the advance was hanging up. If not, it's probably carb rebuild and synch time. With the not revving when cold, it might really suggest that the bike needs some TLC...carbs, general tune up, valves, etc.

Kurt in S.A.

[George Ryals]

There's a good chance that someone set the idle (mixture and fast idle screws) without getting the engine up to full temperature(25-30 minute ride). Try setting the mixture screws and throttle stop screw with the engine warmed up.

[Duane Ausherman]

Kurt, you are thinking that it won't idle down because the flyweights are in the "out" position. This won't rev up, so if it is the stuck weights they are in the closed position, the opposite situation.

I would first check the timing advance, as it could be sticking in the retarded position as I mentioned above. Do you have a timing light to show the advance?

Kurt, and everybody else, don't ever use the clutch to slow down the rpm and get the weights to pull in. You are just wearing out the clutch for no reason.

As mentioned on my website, just pull the key for long enough for the engine to drop in rpm. Then shove it back in and see if it goes back to high rpm or stays. This isn't the case for the above mentioned symptoms.