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1996 Yamaha Big Bear 350 SE with no power

ljungman

By ljungman
in Yamaha ATV Forum

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ljungman

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Ok, so last month I noticed my 96 Yamaha big bear 350 SE was lacking power. I took off the clutch cover and found the centrifugal clutch was very worn. I replaced the clutch with a 2ed hand one that was in good shape and has lots of material left on it. I also replaced the clutch packs as I figured I might as well for the extra $40 seeing as how I had it apart. Changed the oil. Have 10w40 atv oil in it now.

So I took it out today and still no power. It starts and idles fine but in higher gears it will bog down and if I try to spin the wheels by pushing against a telephone pole, ect it will just start to push and then bog down. It won't spin the tires at all under load.

-I've cleaned the carb a million times.

-No holes in any intake boots ect.

-Air filter is clean.

-I've adjusted the clutch from one extreem to the other with that little screw on the side with no change at all

-I've played with the air/fuel screw on the carb with no change at all

-I haven't really checked compression but it will blow my thumb right off the hole when cranking

It just started doing this suddenly and I'm running out of ideas on what it could be. Any thoughts?

Edited by ljungman
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ljungman Rookie

ljungman

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Thanks,

Did some more tests today.

Compression is great and built up fast.

Timing is spot on.

My spark however....refuses to jump anything over 2.5mm and the manual says minimum of 6mm so I guess I'm looking at a new coil. Also I'm trashing the 2ed hand Centrifical clutch in favor of a new one....$300....ouch....

Anyone know how to check my exhaust for restrictions? So I just remove it and blow in it or wa? lol

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  • 4 weeks later...
ljungman Rookie

ljungman

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Ok, so. I replaced the Stator and cintrifical clutch. I'm not sure what was the bigger problem but after tests I found both were gone. She runs great now, and the spark will jump about 30mm which is about the limit of my tester. Alot better than 2.5mm!

I took the time to also replace the coil as it was only $20 and the clutch packs since I had it all apart. Nither was worn that bad but I figured what the hell.

Thanks for the help!

Edited by ljungman
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