1987 Yamaha Big Bear 350 4x4 No Spark

[Nick Gudex]

Hello I am new to this site and I havea problem. I have a 1987 big bear 4x4 that will not spark. I tested pick up coil per repair manual and I tested my new coil both ok. It puts out 9 volts at the coil but It is reversed polarity. So when I hook my meter up to it she shows -9 volts while cranking. When I put a test light  on it it flashes. Being an electric system this should tell me something but I don't know what its telling me. I have yet to meet one i could not fix but this old girl has me stumped. Any help would be awesome. Thanks to all.

Nick

[Scott M]

Does this quad have a source coil? It is much like the pickup but a little bigger. On the 350 Warriors this is a very big problem. Engine oil heat kills these coils. The best way to get this coil is just buy the whole stator. 

Your showing voltage says the pickup is working. I'm starting to wonder if you are actually testing the source coil? Have you tried reversing the polarity just to see if it sparks? Does it have 2 coils there? Or just one? If it has two then one is the source and one is the pickup. 

[Tom Bauer]

Has ignition switch been replaced? Only a genuine Yamaha switch will work. Any aftermarket will have NO spark. There are 2 pickup coils, 200Ω each and 1 source coil 300Ω.

[NoDeer]

Was having a similar problem with my 1987 350 Big Bear.  It had been used under very dusty conditions by previous owner.  Pulled the rubber boot off of the back of the on/off key switch and it was stuffed with dirt, shorting out the switch.  Engine would turn over, but no  spark.  Cleaned this boot out, never have had that problem since.

Edited November 10, 2020 by NoDeer