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2002 Yamaha big bear 400

Old Apr 7, 2024 | 12:24 PM
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Default 2002 Yamaha big bear 400

Hi, need help. I've just recently got a Yamaha big bear 400 with a no spark issue, I was told it ran great before it lost spark anyways it turned out to be the cdi box. I have spark now and I've replaced the ignition switch, coil,spark plug, and also bought a new oem carburetor for it,checked all the wiring did all the test on the stator,pick up coil,rectifier, everything I can think of but it runs bad. It will idle fine but when I go to rev it up cuts out and backfires. I've adjusted the air/fuel mixture screw all the way in and out with no change. I'm at a loss any help would be greatly appreciated. Thanks.
 
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Old Apr 7, 2024 | 06:56 PM
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Is CDI oem? check charging system? brake switch maybe sticking or not working the cdi think the brake is on an put it limp mode
 
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Old Apr 7, 2024 | 09:34 PM
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It is a oem cdi box, checked charging system, I unplugged the rectifier and still does the same thing. But I will check the brake switch I didn't think about that. Thanks for your help I'll update when I get a chance to check it.
 
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Old Apr 9, 2024 | 07:10 AM
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Update on the big bear I unplugged the brake switch and still runs bad.
 
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Old Apr 9, 2024 | 06:34 PM
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I think it has to twist tie wire together I cant remember to make a loop is brake light on?Is CDI new or used?
 
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Old Apr 10, 2024 | 05:25 AM
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Oh okay I'll try that. The cdi box was used bought it off of ebay. Thanks.
 
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Old Apr 10, 2024 | 10:45 AM
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Can you post a video of this atv running let us hear it?
 
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Old Apr 10, 2024 | 10:49 AM
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I'll do it when I get home from work today.
 
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Old Apr 10, 2024 | 05:17 PM
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It will not let me upload a video.
 
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Old Jun 7, 2024 | 03:04 AM
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Any update?
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Edit: Thanks for the update.
 
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