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Discussion Starter #1
I just bought a 98 grizzly 600 that will run okay, but the idle adjustment screw does mostly nothing unless i get it too low, it occasionally has a high idle that i can correct by shaking the quad, and sometimes shaking it kills the engine.

I THINK i found the problem, I sprayed carb cleaner around the carb, and the engine slowed and died when I sprayed it on the intake manifold where it attaches to the head.

How are those sealed to the head?

And, is that likely to cause all of these problems or am I looking for a separate issue as well?

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If I remember correctly there are just orings between the intake and cyl head. Also take a good look at the rubber manifold that attaches the carb to the intake. It was cracked and leaking on mine. A vacuum leak could definitely cause some of the issues you have. At any rate I would fix the obvious problem first and re-evaluate from there.
 

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Discussion Starter #3
Ok, gotta search for the o-rings then. I was thinking about replacing the boots but may not. They arent leaking, yet. But Ill be sure to inspect them thoroughly.

I think I'll go ahead and rebuild the carb while im at it. Some PO buggered up many of the screws including the bowl drain.

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The carburetor adapter (between carb and cylinder head) has 2 O-rings on it that seals it against the cylinder head. These can dry out over time and leak. Additionally, corrosion can build up in the area causing a leak.

That carburetor adapter could also be cracked. That happens from to time. This will also cause an air leak.

Do not ride keep running it with an air leak like that. It causes lean mixture condition, and this will lead to piston burning and/or valve burning. It also cause damage to the exhaust from deceleration backfiring.
 

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Discussion Starter #5
Okay, I ordered a used crack free adapter, new boots, and a carb kit. Just need the o-rings, then I'll adjust the valves, replace the manifold and boots, and rebuild the carb.

Hopefully this will cover my bases. Also going to replace the petcock and make sure the tank is clean.

Funny enough, the petcock doesnt leak, until I turn it, then it dumps fuel until I stop turning it.

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Discussion Starter #6
Tore the grizzly down today, and found a few issues.

One, inside of the carb boot is aging, but not cracked through. Already have new ones on the way.

Two, the mixture screw was installed incorrectly. The washer was on the bottom of the spring, and the o ring was intertwined with the spring. So that's likely contributing to the problem.

Three, the intake adapter o rings are deteriorated. Likely the biggest problem i had.

Side note, is it a problem that the insert surrounding the carb slide is wearing? See pictures.



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As long as the vacuum slide still moves smoothly, then a little wear is fine.
 

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Discussion Starter #8
Well, all together and she's running great. Just gotta dial in the mix and it'll all be great.

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