QuestionHi Chris,
I am trying to revive a 650 that hasn't been ridden for 10 years. It is in generally good shape with only 5000 original miles.
I can't get a spark on either cylinder. I can get sparks across the points when I short them, but that doesn't result in a spark at the plug.
I removed both coils, and they both read 0 ohm resistance across the primary, while the manual says they should have 3.9 meg ohms. The secondary resistance seems OK.
The local mechanic says that BOTH coils wouldn't fail at the same time, so he thinks that the manual may be wrong. It is a factory manual for the 650SE; I have a 650SF.
Am I in for two new coils? How can I test the output voltage of a coil?
Thanks very much in advance.
Jan de Groot
AnswerHi Jan.
I have always followed what the factory manual says, but if you are in doubt, then go to a Yamaha dealership with your manual and the readings that you got and ask the factory mechanic. He/she should know for sure.
I seriously doubt that there is a significant difference, as far as the coils for the SE and the SF models, but check that with the Yamaha parts guys and/or mechanic as well.
As old as the bike is, both coils could have gone. Maybe not all at once, but the bike did set for 10 years. Did you ask why it sat for so long?
Make sure that you reseal the tank and give the carbs a good and thorough cleaning as that could be part of the problem as well.
As far as testing the voltage output of a coil, just hook it up and pull the plug that it connects to. Attatch the plug to the coil as normal, leaving the base of the plug in contact with metal on the engine and try to start the bike. You should get a nice bright blue spark. If you do not, then you either have a bad coil, a short in the ignition system, or a bad plug.
Give the electrical system the once over with a multimeter as well as visually. You will be checking for shorts, bad/dirty connections, bad fuses and bad fuse connections.
Good luck.
FALCON
