Technical Q and A for classic motorcycle maintenance and repair.
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Q: I have a Sears 106SS motorcycle that I won on auction. I had the bike shipped to my house. I got it running great, and it looks awesome. It starts on the first kick all the time. My only problem is that when I hit the rear brake, the bike bogs down like I am hitting a kill switch. I checked the wiring and it looks fine. I also put in a new bulb. The brake switch has two wires that are connected together and just push into the back of the switch. I am having trouble locating that switch. These bikes were manufactured by a company in Milan, Italy. The manufacturer is called Gilera. Can you help me out with any suggestions? Thanks for your help. — Mark Canavin/Aston, Pennsylvania
A: I haven’t had any luck finding a wiring diagram for this bike, so the following is just guesswork. My 1964 Triumph T100SC with Lucas ETC ignition can do a similar thing if the rear bulb shorts out, as it grounds the flywheel magneto ignition and the engine dies. Try removing the taillight bulb and see if that makes a difference. If it does, there is something wrong with the wiring of the bulb or socket; probably hot and ground leads are switched. If it makes no difference, then the problem is farther up the chain. Try disconnecting at the brake switch and testing again. One of these things should be the culprit. Good luck, and do let me know if any of this works or if I have to delve deeper.