Breaker points 180 degrees out of alignment?

[loudboy]

I am rebuilding a 1971 CB350k. This is my first bike, but I am far from unfamiliar with wrenching on machines.

This problem has got me stumped though. I am putting the breaker points back on and roughing in the ignition timing and points gap. For timing the instructions are to align the proper marks on the alternator and then rotate the breaker-points mount slightly until the left-hand points just barely start to separate. When everything is aligned as per the book, the left hand breaker is wide open/nowhere near fine tuning range. I can see the flat part on the cam that is supposed to let the gap close, but it is 180 degrees from where the follower is for the left hand breaker (See picture).

I have checked and rechecked and triple verified that my alternator is mounted correctly and aligned to the crankshaft correctly, the camshaft is aligned to the alternator/crankshaft, and that everything else matches up like it should. So what the hell is going on here? How can I possibly be 180* out of whack?

Thanks all!

 

[Flugtechnik]

Did you disassemble you mechanical advance? I think it is possible to reassemble those 180 deg out.

 

[frogman]

Did you disassemble you mechanical advance? I think it is possible to reassemble those 180 deg out.

+1 Very easy to do, made that mistake myself, Make a mark on the front of the advance once you figure it out so you can remember the next time you are in there.

Can also check for proper time by watching the intake follower on that cylinder go down and then back up. Once it does, that is the bottom of the compression stroke, one more 180 degree turn and it is at TDC.

 

[noexit]

I did the same thing. Twist the center to full advance and you should be able to pull it out, and put it back in 180° from where you had it.

 

[crazypj]

Common fault, points cam is on retard mechanism 180 degrees out (or, you need to turn engine 360 degreesas it could be on 'wrong' TDC, cam turns half crank speed)

 

[Sonreir]

Also... left point is blue. You have it wired to yellow.

 

[DrJ]

Advancer cam has a small notch that should be at top when left cylinder is at TDC before compression stroke (both valves closed).

 

[frogman]

Also... left point is blue. You have it wired to yellow.

Hey Sonny, every picture I have is yellow to the front (left side) blue to the back (right side) like he has.

 

[loudboy]

Wow I feel like a n00b.

Thanks for the quick replies!

crazypj, you were right, I was at TDC for exhaust. D'oh! And DrJ, I see that notch now that you mention it. That sucker is small...

As for the wiring: I replaced one point at a time, so the wiring is the same as when I got to it (never assuming that is stock though).