300ex dies after getting hot


Im trying to help my friend figure out whats wrong with his quad. It runs good for about 5-10 minutes then dies and won't start till cooled off again. I know its electrical and was kinda thinkin it was the coil, but wanted to see what you guys thought. Its not at my house so I havent checked anything with a voltmeter or anything like that yet.

i have the same problem, no spark, but i can bum start it, but once it gets hot it dies and will not start,

friends have told me it has to be the stator but im waiting to get a hold of a volt meter to test it

Check the coil as well..

When you get to look at it, start it up and run it till it dies. If you have a spare plug, pull the coil wire off and plug the spare plug in and hit the starter and see if you have a spark. If you have a spark ask your friend how long has it been since he adjusted the valves.

just for grins i put a new coil on mine, and no luck, still no spark, went ahead and checked all the valves and theyre still in clearance.

any other ideas?

Check all the connector plugs in the ignition system. Maybe one of them is corroded. Or it could be the ignition pulse generator going bad. Or the ICM. Sometimes when electronic devices are going bad they will freak out when they get hot. Also sorry if this is a stup question but have you tried a known good spark plug? Just throwing any possible ideas at it. :smirk:

Ok, this might be another stupid question, but when you check for a spark you had the spark plug grounded to the engine right? I just got to thinking if it actually is sparking you might want to look at the gas cap. If the vent is cloged it could cause a vacume in the tank and stop the fuel flow. Just throwing another idea out there.

sounds like a fuel problem to me is your carb runnig dry? And it wont start until it fills back up either from the gas tank creating vacum, clogged petcock, clogged needle valve in carb check all.

my problem is not fuel, its that there is no spark to begin with ive tried 2 new plugs and a new coil still no worky

If its a spark problem You'll have to check each part of the ignition system to trouble shoot. Make sure all the plugs and connectors are clean and make good contact. Do you have a service manual. If not you can download it here. http://www.sendspace.com/file/wcy9is Don't try to think the whole system at once. Just look at each component indivigually and check it according to the manual specs. There are only a few parts in the system that can go wrong. There may be some checks that require some special equipment. If you get totally stumped you can always take it to a shop and pay them to find the problem and you can fix it at that point yourself and save some $. Just because you take it to a shop dosn't mean you have to let them fix it. Just ask them to give you an estimate on the cost of the repair. The estimate should say what needs to be fixed and you can do it yourself and know its done to your satisfaction. Electrical problems can be a PITA to trouble shoot if you don't have the right equipment. :smirk: Don't know if this is much help. If I had it here I'd have a look at it myself.

Start at one thing and eliminate parts until you find the problem. Easy as pie!

Check the easy ones first. get fuel? got spark? gets air?....no fuel, look at that system...no spark, look at the things that make spark...coil, stator, pickup coil, and the worst!!! the CDI box...make sure the air intake is clean...anyone of these is the problem...now you need to narrow it down....if you can bring your cdi to a shop or test it on another same bike...

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