Topic: cb750k2 timing question

[amattel]

I went out to adjust the timing on my bike today... cb750k2

checked my dwell and it was at 40 degrees (4 cyl scale) on both 1/4 and 2/3

while I was adjusting the timing with a stroboscopic timing light, I noticed that the 1/4 timing was unsteady.. moving back and forth about 1/8 inch while everything was all tightened down while 2/3 timing was dead on with no movement whatsoever.

why would 1/4 be so unsteady and 2/3 so unmoving when all is tightened down?

I believe the movement percieved under the strobe would indicate that the ignition was firing unevenly.. which could mean ??

thanks,

Adam

[TwoTired]

I had a similar issue with a Cb550.  Turned out the point cam was scored/ groved.  Sometimes the point rubbing block fell into the grooves sometimes it rode up on top.  A new, smooth point cam stabilized the timing.

Cheers,

[amattel]

Thank you TT,

I just checked out the lobe of my Advance unit and it is very badly scored...

Honda wants $92!! for a new one.  Classic cycles has a new one for $52.

Ebay has used ones for 15 including shipping.  I just have to establish that they aren't scored as well.

Perhaps it is time for me pick up the $120 dyna s from zr1 and bypass the whole issue.

Adam