coil problems

Youll need an ohmmeter to test the primary & secondary parts of coil . If you have one Ill tell you how . If you dont Ill give you a hint first : We replaced more than a couple of these in the past and they are the only real ign component on the bike besides the kill switch so if the kill switch is good you probably need a coil assy . The coil assy/flywheel air gar can get out of range so youd want to check that too . Its like .040 inch or so .Or you could take a matchbook and put it in between the coil and flywheel . The keyways sometimes sheared in these bikes but sometimes they would still have spark . Onwe time a little guy filled up the motor with water when wasing his bike and hydrod the motor and when his dad kicked it over it locked up and then he pumped out the water . His dad was embarrassed to tell us this so he brought the bike in and we didnt know. It had spark gas & comp but the spark at wrong time . Its kinda hard to kick these little things over when youre a adult . You end up hitting your knees on the bars or footpeg . We kicked it over by hand and it popped and started running backwards so we knew it wasthe keyway. Always test forspark on those little ones with theshop lights off .

It's most likely the coil. I replaced 3 in less than 1 year on my boy's 2001 CR50. BTW, we got rid of that nightmare. I had almost as many $ invested in repairs as the initial purchase price!

I had a similar problem on a YZ 80. It turned out to be the spark plug boot which attaches seperately to the coil wire on the YZ. You can check this with an ohm meter. It was a $2 repair. :)