1968 Cimatti C100 Magneto Mystery

Check out this reader's question about a 1968 Cimatti C100 and the degrees before the top dead center should fire the engine.

Reader Contribution by Graham Quisenberry
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by Keith Fellenstein

Editor’s note: If you’re having trouble with that old Suzuki, BSA or BMW, Keith Fellenstein is your guy. From motorcycle tuning tips to detailed motorcycle engine repair, he can draw from a wealth of experience to help guide you to success. Send questions to: Keith’s Garage, Motorcycle Classics, 1503 SW 42nd St., Topeka, KS 66609, or send an e-mail with “Keith’s Garage” as the subject.

Q: Hi, Keith. I enjoy reading your column. My question is simple, I think. I am doing repairs on a 1968 Cimatti C100 (Costuruzioni Morini Franco), Engine No. N001341. It uses an ASL226S Dansi magneto. How many degrees (or millimeters) before top dead center should the engine fire?
— Graham Quisenberry/via email

A: That’s a tough one. I’m not at all familiar with that brand. If you have easy access to the flywheel over the magneto, look closely at the perimeter of the flywheel. Oftentimes there are two marks on the flywheel, one for TDC and one before TDC for when the points should open. Those should line up with another scribed or cast mark or notch on the case itself. I’ll keep looking for a definite answer. Thanks for a tough question. Update: I have since received a phone call from Graham’s mechanic, who had better luck than I digging up information on the timing. The specifications call for the points to open between 1.8 and 2.0mm before top dead center. He also said there were no marks anywhere on the flywheel or case for reference points.

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