electrical problems

[yzrider_69]

ok i need some help. ok the other day my bike wouldnt start and wasnt getting spark so i toke coil off and tested it it was fine i put it back on and it ran, so i ran it for a couple of days, then died again, no spark. do you think its just a bad coil that acts weird because if it was the cdi it would normaly die and stay dead and i checked all the wires and they were fine all i can think of is the coil.

 

[overbore]

Make sure that its grounded good,which might be what you did
when you took it off and put it back on.

 

[zoommx]

I fought my yz for weeks fouling plugs before fixing. I had checked all kinds of stuff down to piston and rings / cylinder clearances before finding the coil had an issue. Measuring the resistance to the frame was a little high, but the resistance to the ground tab from the coil was right in the specs ( I think about 27 ohms ) so I put some soldering flux at the joint and cleaned as good as I could and then put some oil on it to reduce corrosion and promote conductivity and the resistance to the frame was back in spec. Not another problem since then (Feb). Of course I was off about 5 months recovering from ruptured achilles.

Good luck,
Roger