Idle Issues

Just got a new (1971) R75/5. Starts easily, runs well, but when I clutch it at stops, it seems to idle high, around 2500 RPM. Anybody run into this problem or have any ideas what it might be? Thanks.

First, it sounds like your clutch lever isn't fully dissengaging your clutch. Need to adjust it. Idle sounds like a different issue, also hopefully just adjustment.

The two main causes of high idle on that vintage bike are: sticking timing advance weights, or an induction air leak.

There is a pretty good test that indicates which. It is not a 100% sure test but is usually a very strong clue.

So with the bike stopped, in gear, andd the high idle symptom present, gently start to let out the clutch while also holding the brake. This will pull the idle down. Release the clutch. If the idle stays down the problem is probably sticking advance weights. If the idle goes back up it is most likely an induction air leak.

Seems like you might have a sticking advance unit which doesn't return to it's rest position after coming to a stop. The next time you have this situation, end up with the front wheel near a wall. With the high idle still going on, grab 1st gear and slowly let the clutch out. If the idle returns to normal and stays there, then this is your problem. Otherwise, see next.

The other thing is you might need to a carb overhaul, at least as a minimum do a carb synch. A carb synch should be done with a fully warmed up engine/carbs, say after a 20-30 minute ride.

@sloane, I have the same bike as you and the idling is also one of my issues. I posted in this forum and got a lot of help from members. You can read mine to see if any of this will be applicable to your situation: https://forums.bmwmoa.org/showthread.php?95380-Airhead-R75-5-poor-idling-and-carb-synchronization-issue. Good luck.