Technical Q and A for classic motorcycle maintenance and repair.
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.
Podtronics and RFI suppression
Q: Last summer I acquired a 1975 Norton Commando 850 MKIII that had been built by a friend. This is an award-winning bike and was well sorted. However, shortly after getting it, main fuses began blowing after putting the bike in gear starting out, I’d get a few inches before it stopped. After much analysis and investigation the builder decided it was the Podtronics unit which was at fault and replaced it at his cost. He then suggested I replace the spark plug covers with suppression ones, thinking this caused the unit to fail. I have successfully started and ridden it very short distances; so far so good. But the weather here has turned cold so it won’t likely get taken on a longer ride until spring. Does this solution sound right to you? I am, not surprisingly, concerned about going far and getting stranded. I know how to disconnect the Podtronics if that occurs, but would then have no charging of the battery so the ride home better not be too long! — Bruce Mitchell/via email
A: I’ve searched high and low and can’t find any indication that the Podtronics regulator/rectifier requires any RFI suppression to operate correctly. If you’re running an electronic ignition system, they usually require RFI suppression in the form of resistor plugs or resistor caps. If you have one you generally don’t need the other. You don’t mention whether your Podtronics is the model with the built-in capacitor for battery elimination. If you had that one and the capacitor had gone bad I could see a situation where it would short out and blow your fuse. I guess it could be possible that your neutral indicator light was shorting out and blowing the fuse, but that would have been a continuing problem that carried over to the new Podtronics. I think you just got a rare bad unit. MC