Expert: Mike Wells - 5/25/2009

Question
QUESTION: It seems odd that they wouldn't have been equally calibrated... it's not vital for a repair, but it is something that i have just never understood.  why did they do that?  thanks!

ANSWER: If I understand your question, you what to know why the timing is different on each cylinder? the reason is as the front cylinder is getting to top dead center the rear on is still coming up. After the front goes past top dead center the rear one is just getting there.
Good luck and happy riding
Mike

---------- FOLLOW-UP ----------

QUESTION: Thanks for the rapid response, mike!  Your answer is dead on as to what the difference does, i was just wondering why they didn't design it to be equal.  was it intentionally offset or was this just an oversight that turned out to be acceptable?  i know that most engines are not offset, and offsetting seems to produce undesirable effects, for instance in a car, on a mower, etc.  Thanks again, and i'll look forward to hearing from you soon!

Answer
Harley have made pretty much the same setup since they starter making the v-twin. Both cylinder rods run off the same crank pin. Since the flywheels run square to the cylinders, the front piston will always hit TDC before the rear. They also use a duel fire ignition, which means that both cylinders fire at the same time. If it were wingle fire, both cylinders would fire at different times. Doing this keeps them from having to use a distributer as well as both cylinders not of different crank pins, like car motors
Good luck and happy riding
Mike