# ATV losing power



## Ray Duve (Jun 26, 2004)

Hello
I am hoping for some help with what may be going on with my Yamaha Timberwolf atv. Very cold blooded and has to be started 10 times before it stays running. Main problem is after 15 minutes of riding it starts to backfire and loose intermediate power before it totally stops running . After 10 minutes or so it will start and run fine until it heats up and repeats the same issue at hand .Replaced the carb, fuel filter and check the gas cap venting and still the same problem. Hoping someone can help resolve any help would be much appreciated.


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## ESOX (Nov 20, 2000)

Sounds like a problem I solved on a buddy's machine with a new ECU. 

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## jjlrrw (May 1, 2006)

Any warning/check engine lights? Not sure the year but my 2006 had a neutral safety switch that would act up when hot. I found this site to be helpful Yamaha Grizzly ATV Forum


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## tdejong302 (Nov 28, 2004)

Sound like a coil or power pack to me.


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## twdhunt (Mar 12, 2012)

Sounds like your Valves might need lashing. I had a Yamaha Grizzly and had to lash valves every couple hundred miles. Just like yours if valves were tight would be hard starting and low power. When valves get hot they expand and make it worse.


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## Ray Duve (Jun 26, 2004)

Thanks for the advice guys I will look at all of the above mentioned.


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## GATORGETTER (Jan 31, 2008)

Late Father-in-law’s 1999 Yamaha Grizzly the stator went bad. Doing weird things like that. I bought an aftermarket replacement off eBay cheap and it’s been great since.


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## 1morebite (Apr 9, 2016)

Yep,
Check valve clearance.


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## MossyHorns (Apr 14, 2011)

twdhunt said:


> Sounds like your Valves might need lashing. I had a Yamaha Grizzly and had to lash valves every couple hundred miles. Just like yours if valves were tight would be hard starting and low power. When valves get hot they expand and make it worse.


I would have unloaded that Grizzly. I still have my 86 Honda 200SX and it has never had the valves adjusted and runs great. I just sold my 2003 Polaris, which I purchased new and never had to adjust it's valves either. I did check my valves on my 2017 Teryx while I had it apart to replace the stator and they were still in spec. I know they can get out of spec, but 200 miles is ridiculous. I would have to do that about every 3 to 4 weeks in the summer.


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## twdhunt (Mar 12, 2012)

MossyHorns said:


> I would have unloaded that Grizzly. I still have my 86 Honda 200SX and it has never had the valves adjusted and runs great. I just sold my 2003 Polaris, which I purchased new and never had to adjust it's valves either. I did check my valves on my 2017 Teryx while I had it apart to replace the stator and they were still in spec. I know they can get out of spec, but 200 miles is ridiculous. I would have to do that about every 3 to 4 weeks in the summer.


I sold it and bought a Can-Am 1000 best machine i have ever had. this is unstoppable. 5,000 miles and only replaced belt and tires.


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## slimpickins (Oct 6, 2016)

I would check the intake if it's the rubber coated one the are always splitting causing all your concerns. I have a Yamaha warrior and has done it 3 times. Now have a intake machined from aluminum problem solved. 

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## mattawanhunter (Oct 30, 2011)

Check around for a good one man shop (less expensive than dealer) with a good reputation.

Well worth the money.

I have one this way anyway!



Ray Duve said:


> Hello
> I am hoping for some help with what may be going on with my Yamaha Timberwolf atv. Very cold blooded and has to be started 10 times before it stays running. Main problem is after 15 minutes of riding it starts to backfire and loose intermediate power before it totally stops running . After 10 minutes or so it will start and run fine until it heats up and repeats the same issue at hand .Replaced the carb, fuel filter and check the gas cap venting and still the same problem. Hoping someone can help resolve any help would be much appreciated.


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