Topic: '77 CB400F ignition timing issue...

[mwc400f]

Greetings,

I gapped and installed new plugs, and replaced the points/condensers on the backing plate. I set the backing plate into the center of the adjustment range, and then set the static timing/gapped the points as per the honda service manual. I set the points at .012, which is the low end of the range. I started the bike, set the idle at 1200, and using a strobe timing light, and successfully set the timing for 1,4 -- although the backing plate was hard against the end of it's adjustment range. I got 2,3 somewhat close, but ran out of adjustment before the timing marks lined up. I did look at the FAQ, the suggestions there didn't gain me enough adjustment.

Any hints are welcomed.

Thanks!

[scottly]

The points gap needs to be set at the crankshaft position where it is the greatest, which is approximately 90 degrees past the F mark, IIRC.

[mwc400f]

Yeah, I should have mentioned that I was using the 90 deg past F as the position to gap the points in my description of the problem. Points are also after-market (not honda), although the backing plate is genuine honda. Don't know if that's relevant.

I am thinking of starting over, with the backing plate moved all the way to the opposite stop, and then start with setting the static ignition timing, then the strobe light. I'll see what effect doing that has.

Thanks for your response,

Regards,
Mike

[bryanj]

Gap should be 14 thou

[mwc400f]

I'll give 0.014 a try. Just a photo on the ignition setup in question...

[dave500]

best to get hold of a dwell meter and timing light,youll never get it truely squared away static compared to dynamic,then youll chase your tail when it comes to the carb settings?

[Little_Phil]

From memory on one of my bikes I think I ended up setting the two sets of points with slightly different gaps to get the advance timing marks right and also within the slots on the plate. Didn't bother to investigate further. But it ran fine enough for me. Dwell is a fixed number, but time when power is applied to coils varies with RPM anyway.

[BenelliSEI]

Any chance your rotor shaft is ever so slightly bent? Can give the symptoms you describe.

[dave500]

also the plate is located by three lugs,theres often a bit of slack to the centering,it can skew the points each time you adjust the timing with it.

[HondaMan]

Uh...is that water dripping off the right-side green condensor's wire at the bottom of its bend? Weird...

Do you know which brand of points you have, and condensors? They are not TEC, that's obvious, but I don't see any ID on them or the condensors.

The Daiichi points are 'off' slightly in geometry. The typical symptom of this is: you can set the "L" points to (or almost to) the "F" mark at idle speeds, but the points plate ends up hard against the ends of the slots with the gap at 0.014". Then it is also impossible to reach the "F" mark with the 2-3 points set. If yours is like this, I may have some suggestions that can help.

P.S. - don't throw away your old condensors yet - you may still need them.