I have a 2005 Marshin wolf 110cc quad that has spark part of the time. I do not mean sometimes it runs sometimes it doesnt. i mean when you crank it with the spark plug out grounded to the cylendar, it will spark once or twice and stop, if you keep cranking it will spark off and on a little after that or quit entirely. No real rhyme or reason to it that i can tell. Has anyone heard of this? any suggestions?

 

just a few questions:
have you tried testing spark with more than just that one plug?
have you measured the voltage coming out of the coil?
is the coil getting hot?
i presume all quick connects on your wiring harness are snapped tightly together.
coil wire itself in good shape with no nicks/cuts/wiring deficiencies/burn spots in wire jacket insulation?
coil could be starting to go out. let me think on that some more.

 

I do have 2 plugs i have tried both are old though. will get a new one and try.
did not measure voltage coming out of the coil. will do.
not sure about the coil heat either. I have 2 of these machines. have been swapping parts too but have not tried the coil.
i have plugged and unplugged connectors trying to be sure of connections.
went to the parts store and made a new spark plug wire.
I appreciate your input and will definitely try what you suggest. i am truly a weekend warrior but sometimes work on this at night and definitely on weekends. BTW, neither machine runs yet and i am working on the one that is not locked up. so i cannot truly determine if the swapped parts are good, only if it makes a difference.

 

Voltage coming out of the coil is spazmodic. acts just like the spark though. good first spark then occasionally. voltage jumps to 10.something for a second then little intermittant flashes off and on. voltage going into the coil is a steady 11.3 something. both coils i tried act the same way.