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'73 CB350

Discussion in 'Tech' started by Paw86, Mar 11, 2009.

  1. Paw86

    Paw86 New Member

    Hello, I don't usually post on forums but I've got a problem that I just can't wrap my head around. I have a '73 Honda CB350G that I just took completely apart and rebuilt the engine. This is my first rebuild of a motorcycle but I haven't had much troubles till now.

    My problem is the left points are controlling the right coil and vice versa. What's really strange is that if I switch the wires coming from the points, I don't get any spark from either cylinder. When I switch the wires back I get a consistent spark, but backwards (left points right coil, etc.). So of course it would be logical to just switch plug wires from one side to the other... if I do that then I get no spark on either side.

    I have tried everything I can think of to get the left points to fire the left side but i either have it backwards or no spark at all. What did I do wrong? I do know that the points are firing in time with the crankshaft, its just that they are firing the wrong side.

  2. JamesG

    JamesG Architeuthis dux

    You have the ignition timing rotor (or the pickup plate) on backwards or otherwise 180 degrees off.
  3. Tinfoil hat charly

    Tinfoil hat charly Well-Known Member

    The coil wiring may be transposed left for right?
  4. JamesG

    JamesG Architeuthis dux

    I think he already eliminated that by switching them around.
  5. Paw86

    Paw86 New Member

    Thanks for the replies! If by the pickup plate you mean the baseplate the points attach to, I am sure it is on correctly. The points are in time with the alternator marks, i.e. the left points spark when the alternator mark is on the LF and the right points spark when the alternator mark is on the F which is the way it supposed to be. However, the left points are firing the right cylinder which i don't think its supposed to be? For this reason I would think that the problem is somewhere between the points and the coil.

    Things I have tried:
    Switching point wires from left coil to right coil
    Switching plug wires from right spark plug to left spark plug
    switching positive and negative terminals on the coils

    The result is always the same, either points controlling opposite cylinder or no spark at all. It sure doesn't make sense to me! Thanks again for the help
  6. panthercity

    panthercity Thread Killa

    I am NOT being a smart ass.

    That said, are you sure that you and the manual are in agreement on which is the left cylinder and which is the right?
  7. Paw86

    Paw86 New Member

    I find that even simple and obvious things can be overlooked so I would call that a fair question. However, i call the left side of the engine the left side as i am sitting on the bike and the book does the same so I am sure I agree with the book.

    If I could just switch the plug wires from one side to the other everything would be great but I get no spark if I do that. Can anyone explain why?
  8. JamesG

    JamesG Architeuthis dux

    Normally on a problem like this you can blame it on a bad electronic ignition, but since this is a simple mechanical points ignition, I'd say something has to be mis-assembled otherwise it wouldn't work at all.

    Cam timing (and thus ignition timing) 180 degrees off? Maybe the generator rotor is on wrong, from a different model of bike, etc?

    Recheck your work and also check the wiring from the points to the condenser and coils to make sure they never got "repaired" wrong at some point in the past (the joys of working on old bikes...).

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