2002 Grizzly 660 won't rev...
Jun 17, 2014 | 05:17 PM
#1
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Weekend Warrior
Joined: Jun 2014
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2002 Grizzly 660 won't rev...
Hey folks! New to this forum. Figured I'd give it a shot and see if I could get some help with an issue. If I wasn't bald, I'd pull my hair out over this one!
I am working on a 2002 Grizzly 660 for a friend. When he brought it to me, he said he had taken it to a local shop and they rebuilt the carb and gave it back to him. When he got it home, he found that it wouldn't run unless the choke was set at right about half on. Any less and it would die out, any more and it would die out. He took it back to them and they said it was a camshaft problem and they don't do that sort of work.
When I got it, he was right. It wouldn't run unless the choke was set at about 1/2 on. It also wouldn't rev up at all. As soon as you would touch the throttle, it would die out. Also, if the petcock was turned on for more than a few seconds (even with it running), fuel would start to dump out of the drain at the bottom of the float bowl even though the drain plug was tight.
I took the carb apart with a new rebuild kit waiting on the shelf and found that this carb was definitely not rebuilt. The bowl was off, I can tell you that for sure, because the drain plug for the bowl drain was replaced and the float bowl was reinstalled with RTV in place of the o-ring style gasket.
After disassembling and very thoroughly cleaning the carb, I installed all the new jets, new float valve, gaskets, etc etc etc that came in the kit and set the float level (which, incidentally, was WAY too high, which caused the fuel to get into the pilot air tube at the bottom of the bowl and drain out after the seat of the drain plug). Once everything was set up on the bench, I reinstalled the carb and hooked a gravity fed auxiliary fuel tank to the carb (no flow issues here, folks!). As soon as I hit the button, she fired to life with the choke all the way on. Good sign! The engine warmed up and I gradually turned the choke off until it was all the way off. Engine idles like a champ!
However, it still won't rev up. I read a lot of posts about the valve lash being too tight, so I went that route. Set the intake valves to .13 mm and exhaust valves to .17 mm. (Spec is I- .10-.15mm, E- .15-.20mm COLD). Still no revving.
I read something about the reverse rev limiter malfunctioning and causing issues, but that checks out too.
I did find that the drain rubber on the bottom of the airbox was missing, so that would allow a little extra air into the stock airbox (still has the stock pipe also). I plugged that temporarily and found that if I cover the air intake on the top of the air box (when assembled), the engine will rev up great! As soon as I move my hand to let more air in, I can hear popping (lean pop) in the exhaust and it bogs out like it's starving for fuel. Cover it back up and reduce the amount of air entering and it revs up again. If I completely cover the opening, it bogs out and dies and you can feel a real good vacuum in the box. It's also hard to restart after doing this since it basically floods itself out. This tells me (along with spraying around with carb cleaner) that I don't have any vacuum leaks causing a lean condition.
Tried a new plug as well and no change. Coil seems to be putting out plenty of spark, but this doesn't really act like a spark issue anyway.
Everything on this machine is stock and the carb is set up as such.
Any help would be appreciated!! Thanks in advance!
I am working on a 2002 Grizzly 660 for a friend. When he brought it to me, he said he had taken it to a local shop and they rebuilt the carb and gave it back to him. When he got it home, he found that it wouldn't run unless the choke was set at right about half on. Any less and it would die out, any more and it would die out. He took it back to them and they said it was a camshaft problem and they don't do that sort of work.
When I got it, he was right. It wouldn't run unless the choke was set at about 1/2 on. It also wouldn't rev up at all. As soon as you would touch the throttle, it would die out. Also, if the petcock was turned on for more than a few seconds (even with it running), fuel would start to dump out of the drain at the bottom of the float bowl even though the drain plug was tight.
I took the carb apart with a new rebuild kit waiting on the shelf and found that this carb was definitely not rebuilt. The bowl was off, I can tell you that for sure, because the drain plug for the bowl drain was replaced and the float bowl was reinstalled with RTV in place of the o-ring style gasket.
After disassembling and very thoroughly cleaning the carb, I installed all the new jets, new float valve, gaskets, etc etc etc that came in the kit and set the float level (which, incidentally, was WAY too high, which caused the fuel to get into the pilot air tube at the bottom of the bowl and drain out after the seat of the drain plug). Once everything was set up on the bench, I reinstalled the carb and hooked a gravity fed auxiliary fuel tank to the carb (no flow issues here, folks!). As soon as I hit the button, she fired to life with the choke all the way on. Good sign! The engine warmed up and I gradually turned the choke off until it was all the way off. Engine idles like a champ!
However, it still won't rev up. I read a lot of posts about the valve lash being too tight, so I went that route. Set the intake valves to .13 mm and exhaust valves to .17 mm. (Spec is I- .10-.15mm, E- .15-.20mm COLD). Still no revving.
I read something about the reverse rev limiter malfunctioning and causing issues, but that checks out too.
I did find that the drain rubber on the bottom of the airbox was missing, so that would allow a little extra air into the stock airbox (still has the stock pipe also). I plugged that temporarily and found that if I cover the air intake on the top of the air box (when assembled), the engine will rev up great! As soon as I move my hand to let more air in, I can hear popping (lean pop) in the exhaust and it bogs out like it's starving for fuel. Cover it back up and reduce the amount of air entering and it revs up again. If I completely cover the opening, it bogs out and dies and you can feel a real good vacuum in the box. It's also hard to restart after doing this since it basically floods itself out. This tells me (along with spraying around with carb cleaner) that I don't have any vacuum leaks causing a lean condition.
Tried a new plug as well and no change. Coil seems to be putting out plenty of spark, but this doesn't really act like a spark issue anyway.
Everything on this machine is stock and the carb is set up as such.
Any help would be appreciated!! Thanks in advance!
Jun 19, 2014 | 02:56 PM
#4
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Weekend Warrior
Joined: Jun 2014
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With the airbox removed, I can partially (mostly, really) cover the inlet side of the carburetor and see the slide moving up. Well, starting to move up until the engine starts to die out.
I set the float level with a clear tube on the bowl drain and set it so that the fuel level is right up to the bowl sealing surface. That is the correct height, yes? I even rechecked it once it was back on the machine to be sure it wasn't tilted or something when I bench checked it.
Thanks for the reply!
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