Can a 903cc be over advanced?

The story to me from several guys has been just make sure the ignition advance is full on by 2350 rpm. My Kaw shop manual from 1977 says that the '76 motor should be at the F mark at 1000 rpm or less and at full advance at 2350 rpm. Does that matter? What if the full advance happens at 1900 or 2100 rpms? If I am looking at this correctly the z1, unlike my 289 Mustang, can't be over advanced. Is this right or wrong? Please explain and tell me where you guys set your advance.

Thanks as always.

Yeah, you will probably be full advance by 2350 rpms or more. The mechanical advance on these bikes do wear over time and as the springs lose some tension you may hit full advance even sooner. It's not really an issue though as 95% of the time the engine is running at full advance.

Now, I will say this. In my own testing and speaking with folks more knowledgable in this area than me...usually the sweet spot for these motors is anywhere from 2 - 5 degrees retarded when setting advance at the F mark. This is where they seem to run best. This is usually due to wear/stretch of the cam chain which will cause an advance condition on your cam timing. Setting it slightly retarded they don't peak out as quickly and tend to run smoother and cooler.

I have one 550 that gets to full advance by about 200 or 300 RPM too soon. It knocks when I get on the throttle too hard. Not good. I'm changing the springs as soon as I get a chance. (I already know the advancer is clean and lubed)

If the little, tiny rubber stops on the advance arms fall off, you will get too much range in the advance. If you set it at idle, it will be too advanced at full-advance. If you set it at full-advance, it will be retarded at idle.