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Discussion Starter · #1 ·
I tried searching for this subject, but there was nothing that matched my situation.

When riding above 4K rpm, the bike seems to surge and I can't keep it running smoothly. It is not a major surge, it is just not running smoothly.

I put my carb synch on and checked them at idle and above 3K and they track exactly the same.

Next, I checked the timing. I pulled the advancer off and cleaned and lubed it and everything is free to move.

After setting the timing on both sides at idle with a strobe light, I checked the advance. This is where it gets interesting.

The left side will advance past the marks, while the right side will only advance to the correct marks. I think this is the cause of my surging running condition. One cylinder is advanced too much and the other is not.

How do I keep the left side from advancing too far?

Not sure if I need to replace the points or is there something that can be adjusted?

Thanks for your help.
 

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The advance mechanism is not adjustable but this can be caused by an excessively worn advance cam or too much play end play in the fit of the advance cam on the shaft. You can check the end play by inserting shims under the advance cam washer and while there is no specification, anything over .005" is probably too much. You can change the end play by inserting a thicker spacer under the cam, I purchased a variety of sizes from McMaster-Carr. If the outside of the cam appears to be excessively worn, you can try a different cam.
 

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Discussion Starter · #3 ·
I understand that there could some axial play, but I don't understand how this would effect only one side.

How can one side advance to the correct degree but the other side overshoots it?

Is there any way to adjust the individual point for the left side to limit the amount of advance?
 

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Adjust the points until both cylinders hit the mark at full advance. It doesn't matter a whole lot if one cylinder is off a few degrees at idle, it runs at full advance 95% of the time, when you're riding it anyway.
 
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