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Discussion Starter #1
I've got a 2003 Grizzly 660. Sometimes it will act like it is going to cut out and die, but most of the time it will keep going. On a few occasions, it has died, but not very frequently does it do that. What could be causing this?

I am wondering if it has something to do with the HMF slip on exhaust and K&N filter that came on the bike when I bought it?

The reason I say that, is it almost sounds like an air issue to me, but I am no mechanic.

Any suggestions on where to look first?

I thought about putting some premium fuel in it just to see if that would help.
 

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Could be something as simple as a vapor lock in the tank. Next time it happens, crack the seal on your fuel cap to see if that solves the issue. Make sure vent tube off fuel cap is operating properly.
 

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First try a new spark plug. Then check the float level. After that check the pulse coil. Don't waste your $ on premium fuel. A can of Seafoam can hurt anything and may help.
 

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My buddy bought a used 660 and it was doing the same thing your's is doing.
I adjusted the valves and installed a new plug and it ran like a top.
 

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You can do it.
You can get a service manual for 10 buck or less on line.
This will walk you through it.
It take more time to remove the tank than it does to adjust the valves.
Let us know when you have a question.
 

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Running way to lean with that setup. Too much air, not enough fuel.Sounds like it needs bigger jets.
 

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Discussion Starter #8
Running way to lean with that setup. Too much air, not enough fuel.Sounds like it needs bigger jets.

I thought it may be getting too much air too.

How hard are jets to replace, and how would I know what jet to get?

It came with the K&N filter and HMF exhaust on it when I bought it. I wish I had the cash right now to take it back to stock.
 

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Sometimes it will act like it is going to cut out and die
What do you mean by "sometimes"? If it's jetting, then the problem would be constant at a set throttle position and would be easy to diagnose by looking at things like spark plug and tail pipe color. If it only happens once in awhile, I wouldn't be looking at jetting.
 

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Is it hard to start? IF yes adjust the valves.
Nothing to do with too much air. Unless it is running out of fuel. All air no gas=no run.
Did you try a new plug?
Do you have an inline fuel filter? If yes install a new one.
I say float as it seems to be running out of gas. Check the float level and for dirt. May need a new needle and seat.
Start with the easy stuff.
 

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Discussion Starter #11
What do you mean by "sometimes"? If it's jetting, then the problem would be constant at a set throttle position and would be easy to diagnose by looking at things like spark plug and tail pipe color. If it only happens once in awhile, I wouldn't be looking at jetting.

It happens less frequent after it has warmed up a bit, but it still happens.
 

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Discussion Starter #12
Update:

It was the spark plug. The Gomer I bought it from tried to put some high-fangled performance spark plug in it that was the wrong size and the wrong gap. It took a 17mm socket to get it out.

I replaced the plug, with the correct gap, and it runs fine now. Thanks for the help guys.
 

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Excellent. Got to love the $2 fixes...
 

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Hey..Bowhunter..Thanks for the report..It help other members when the fix is posted.
 
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