Honda ignition problems
Q: I read the Q&A on the MC website about Honda CX500 ignition problems. I am rebuilding a 1980 Honda CX500C, with the 3-piece stator you discuss. My problem is the bike starts beautifully when cold, and runs well even when fully warmed up to running temperature, but if you switch the engine off it refuses to start again until cooled down. Checking for a spark when cold, it shows big fat sparks, but when hot, nothing or just the very faintest visible spark. Do you think this could be the low-speed stator winding or the CDI unit? Any advice for testing both would be greatly appreciated, as well as advice for replacing the units with modern replacements. (They don’t seem to be available any more, except used ones on eBay which could be just as problematic). Many thanks.
Charlie Watt/via email
A: This ignition system has not aged well. There are a few tests you can do to help pinpoint the failure origin, and rather than rehashing them here, I’m going to refer you to Motofaction, which has a detailed troubleshooting guide for both the CDI and transistor ignition systems. If, after troubleshooting, you find the stator to be the problem, Rick’s Motorsport Electrics sells a replacement CDI stator.
Oil capacity
Q: My name is Doug Bottcher and I have just bought a 1966 MV Agusta Germano 49cc pedal start moped for my wife. It has been in static display in a collection for several years. My intention is to put this bike back into service. It has spark and good compression. It has a very small Dell’Orto carb and should be an easy fix to put back on the road. The gearbox has been drained of oil. My question is would you have any idea of the correct oil capacity for the gearbox/clutch. Any assistance you can give would be greatly appreciated. I am a Bultaco guy and have no knowledge of Italian bikes. Thank you.
Doug Bottcher/via email
A: That’s an interesting machine, but I can’t claim to know anything about it. I did manage to find out the engine was sourced from DKW, but still no concrete info about gearbox capacity. Thanks to the efforts of Amanda at LF Scooter here in Lawrence, Kansas, I found some possibly useful specs. This engine is similar to a Zundapp 49cc engine, and the gearbox capacity is listed as 350cc. SAE 80 is the recommended gear oil.
Comstar wheels
Q: I have a 1979 Honda Gold Wing that I rehabbed and set it all up with a Vetter system for touring. It has the Comstar wheels. My question is can tubeless tires be mounted on these wheels safely? They run cooler and are easier to patch if need to be.
Rick/via email
A: Since those wheels have a hollow extruded aluminum rim, it should be possible to use tubeless tires on them provided the valve stem hole in the rim is shaped for stems. (Editor’s Note: Keith revised his answer to this question in the September/October issue.)
BMW revival
Q: I’ve been reading your column for years and really enjoy your thoughtful answers. I have a question that maybe you can help me with. I have a 1977 R100/7 BMW that I haven’t used for about 10 years. It was well maintained before I stopped using it and I drained the carbs and gas tank and placed rags in the mufflers and intake to keep rodents out. I don’t remember if I squirted oil in the cylinders but probably did. I recently installed a new battery and I can’t seem to get the engine to turn over. I can hear the starter struggling but that’s it. What do you recommend as the first step to make sure the engine is free to turn as this has no kickstarter.
Doug Davis/via email
A: Thanks for the kind words Doug. I appreciate them. There’s at least two ways you can try to turn the engine over without a kickstarter, and they both start with removing the spark plugs. The least difficult method then is to put the bike on the center stand with the rear wheel off the ground. Then shift into 2nd or 3rd gear and try to rotate the rear wheel. It will take some effort, but you should know soon enough if the engine is seized. The other method requires you to remove the alternator cover at the front, first disconnecting the battery so you don’t short anything out. You can then use a hex key (5mm, I think) to turn the alternator clockwise as it’s directly connected to the crankshaft. It shouldn’t take much effort to turn it, so use caution, you don’t want to snap off the alternator fixing bolt.
Triumph mechanic
Q: In a past issue a reader asked for a Triumph mechanic recommendation. Jim Romain is a mechanic who specializes in Triumph motorcycles, especially the T-150. He is located in Cloverdale, California (north western California). (707) 696-5004 (cell) or (707) 857-3790, jsromain@comcat.net. He also has a ’74 and did great work on my 1971 T-150. I also have a question. I just finished going through the timing side of a ’66 BSA Spitfire Hornet which included an oil pump rebuild. I was told that oil lines in that part of the engine must be primed with oil before reassembly. I had never heard that before. True or false?
John Damon P.E.
A: I just refreshed my memory by reading the lubrication section of the shop manual and it doesn’t say a word about priming the oil lines. I restored a same year Hornet a few years ago and went by the book. It wouldn’t hurt anything if you wanted to do the extra step. Thanks for the info on the Trident mechanic.
Email questions and feedback to keithsgarage@motorcycleclassics.com.
