I was given this 4 wheeler by a friend. It has been sitting up a while and has no key. I have gotten around the no key and am trying to make the thing start. I have no spark at the spark plug. Is there a wire in the key that grounds the spark or is that all done from the kill switch on the handle bars. How can I check the coil and other parts of the firing system. THanks for the help
The heading is labeled wrong this is an YFM-80 moto 4  

I found that I have a nice hard spark , I have sprayed starting fluid into the spark plug hole and it will not fire. Sometimes it seems to get real close to running but so far it hasn't anyone have any tips for that.  

Hey.  I have same make yamaha w/ same problem.  It does not fire (no spark) w/ electric start.  Although when jumping it by poping into gear it sounds very close to starting.  I have tried starting fluid in carb as wellas cylinder w/o success.  Have you had any luck.  Please let me know of successful maneuvers and I will post my findings.  I hear the carb may need cleaning.  On breif visual inspection it appears clean, and ai would think starting fluid in cylinder would prompt firing.  

the carb is most likely dirty. The jets and the float pin should be cleaned out and if it has a spark it should start. If it dosent start after that it is probably electrical  

briceis right, most likely the carburetor is dirty.

also have you dumped the tank and added new fuel?