Motorcycles, Snowmobiles, Go-Carts, ATV's and Golf Carts - 98 yamaha 600 grizzly keeps quitting, but not loosing fire.

Hello. I was wondering if any of you could help me with my 98 600 grizzly. I can start mine and run it no problem for about half hour. Then once it gets really heated up it will backfire and quit. Ive checked the spark and it still has fire, but will not start. not sure how strong the fire is, but it has a new coil. I let it sit for 5-10 minutes and it starts back up, runs fine for 5-10 minutes, then backfires and quits again. Ive replaced the coil and had the stator tested at a yamaha dealer. No problems showed up there. IF it were the CDI i shouldn't have any fire at all when it quits right? I'm not sure what to do next? They suggested that it could still be the stator or possible the wiring harness shorting out someplace? Ive also put in a new carb kit thinking it was a carb problem... ive also cleaned out the tank and the screens and replaced the fuel line. Ive ran it with no gas cap too to eliminate any fuel/air locking and that wasn't it either.
Any ideas? Thanks, Wade

Picking this up from the other thread... Yeah, the windings in the stator could be developing resistance while they are running, then fail. When they cool down, everything works again. A coil can do the same thing.

The next time it dies, if your battery is fully charged, break the connection coming out of the rectifier and see if it starts right back up for you. If it does, don't run it that way, but hook everything back up and think in terms of a bad stator or rectifier.

You can check a stator with an ohm meter while its cool and it may check OK, but when it heats with loading everything changes.

thanks for the ideas, i will try the rectifier trick next. I just left the yamaha dealer and they told me the same thing about the stator, that it could be breaking down under load. Is there anyway to test the rectifier itself? Another thing i was thinking about, is i have noticed a small air bubble in the fuel line every once in awhile, which makes me think about a fuel issue at the carb.

just another idea, if the battery were not the exact factory replacement, would that affect the rectifier and make the bike quit? the battery seems to be charging fine.

On the battery - no, it wouldn't have to be exactly the same, just the same voltage naturally and enough amps to crank over your accessories, ie the winch and starter.

On the rectifier - if your Yammer Hammer guys don't have anything an automotive electronics shop may be able to test it under load. A lot of guys treat it about the same as the CDI box, which no one seems to be able to test = try a known good replacement. I can't say that's ideal for diagnosing something but it's pretty common.

Usually a rectifier will have output at a specific voltage that can be checked, though. The catch is you have to do it under load and you're relying on the condition of the stator which feeds the rectifier.

I don't know about the air bubble in the fuel line. I don't believe I'd put a lot of weight on that. With a gravity fed delivery system the air could just be coming back up from the air space in the carb bowl when you hit a bump. That space is vented into from the carb throat.

When the little beast dies does it bog down or just quit like the ignition has been switched off?

i'll try testing the rectifier then and checking the carb situation. hopefully i'll stumble upon the fix sooner or later. Thanks alot for your help. Wade

Hi there i have the same ATV with the same problem as you had it runs good the firts 30 minuits then dies and backfires. I was wondering if you solved your problem and if so could you please help me out if you could that would be great. thanks, Jack

HI, sorry, mine still quits all the time. It seems to run sometimes longer and sometimes shorter when i tinker with the carb, but not totally sure the carb is the problem. I had the stator out and tested and it tested low, but ok to run, but they suggested at the yamaha dealer that the stator could be breaking down when running and hot... Ive been thinking that the engine might be overheating a bit before it quits, but i havent really done too much with the bike, i just get too aggrevated every time i try something new... My gut feeling though is that it is either the stator and/or the carb... Just not getting the right fire and fuel air mixture to stay running for long periods of time... It's also been suggested that it could be the rectifier overcharging the battery and once its at its max, its messes with the bike. I found a website with stators for 200 and rectifiers for 100. its www.rmstator.com. they are out of quebec, canada. they seem reasonable. i called and they said that the stator would cause my bike to quit like it is... i just havent had the money to put into it right now, maybe someday... I shoulda just bought a honda eh... lol... I hope this helps a little. If you do figure your grizzly out, please let me know. Id love to be able to run mine other then around the house and then pushing it back into the garage. Good Luck, Wade

Hi there i have solved the problem the engine covers by your knees when you ride mut be removed and it helps the engine cool down a lot. These quads are ment for going fast oin trails and that keeps them cool. Try taking off the covers on the sides plates off your engine. And Make sure your rad is clean.

Hope this helps,
Jack.