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, 1503 SW 42nd St., Topeka, KS 66609, or send an e-mail with “Keith’s Garage” as the subject.
Q: I have two 1985 Suzuki Madura V4s. One is a 700 and one is a 1200. They are great bikes when running, but both share the same problem: They are hard to start when cold. I have installed new batteries, new plugs and wires, cleaned the carbs, and cleaned the connections and ground wires. Both of these bikes will nearly start when I first hit the starter, and after that they just turn over but won’t even try to start. If I spray a little starter fluid into the air cleaner, they will start right up. I’m thinking the spark may be weak. What you think of Dyna coils or equivalent, or am I on the wrong track? — David Durtschi/Utah
A: I usually don’t even think twice when someone says a mid-Eighties bike is hard to start or won’t idle. To meet emissions standards, bike manufacturers had to set the idle mixture as lean as possible. Sometimes it seems to be set leaner than possible. Add to that modern formulations of gasoline, including the addition of ethanol, and you have a ready-made set of problems. You should start from the manufacturer’s setting for the idle mixture and be prepared to go richer than they recommend. Another consideration on the Madura is the fuel pump. I recently had one in the shop that was hard to start and I found the fuel pump had quit working. The original pump is quite expensive, but I found an inexpensive electric pump from NAPA to take its place. It can be difficult to find parts for the carburetors, so be careful not to lose any parts if you have to remove and clean them. Reasonably priced bowl gaskets are available from siriusconinc.com. If you do remove and separate the carburetors, you’ll have to synchronize them when you reinstall them. I found that once I replaced the bowl gaskets, bench synced the carbs and replaced the fuel pump, the big Suzuki was an easy starter. Final running synchronization improved things even more. MC