Motorcycle Repair: cb400t too advanced.., open throttles, cb400a

Question
I have a cb400t 1978 motorcycle.  It will run but very badly and unreliably backfiring through the carbs the whole time.  I checked the timing even though it's not adjustable with this cdi but it's way too far advanced.  It seems to be firing right when the pickup on the rotor gets to the first piece on the pulser thing, at least I think that's what it is, and at that point it's about 30 or 40 degrees advanced past where it should be, I'm surprised it even runs.  Any ideas?  Any help would be very much appreciated!

Thanks,
Matt

Answer
Matt, Honda had a tough time with the CDI ignitions in 1978. All the CB400A machines had their ignitions replaced under warranty. The parts for the automatics are different than the manual transmission versions, so hopefully you don't have a mix of parts in the bike.
The module may have gone south or the pulser coil could be having difficulties, which is often the case, but usually they just quit. The module controls the spark timing advance, I believe.

Other possibilities are that the keyway has sheared on the flywheel/rotor and everything has shifted. Verify that TDC (T mark) on the flywheel marks coincides with the piston at top dead center.

Also, perhaps the cam timing is off due to someone working on the bike and failing to set the cam in correctly.
Check the compression first... should be around 175 psi with open throttles. IF both sides are way down into the 100-140 psi range, then the cam timing is out a tooth or the engine is way worn out.

Bill Silver