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Discussion Starter #1
Hi everyone! I'm new here, have been lurking behind the scenes for a while, just now registered. Just so you'll know, the username has nothing to do with Polaris, it's from the TV show Rawhide, if anyone remembers that? :)

I have a 2003 Griz that I've owned since new, no mods, driven daily. Fired it up the other day, went about 100 yards and it starting backfiring, coughing, sputtering, just thowing a fit. Engine hadn't even warmed up yet. I changed the plug and that did not help.

It would start and run with choke on, smoke like freight train. With choke off it would backfire, spit, sputter and didn't want to rev without dying. With choke on I coaxed it to the road and ran it up to 55-60 mph. It didn't seem to miss a lick at high rpms with choke on. Prior to this problem, the choke would/should have killed the engine?

At high rpm's and 50+ mph, I could turn choke off and it would continue to run flawlessly until I let up on the throttle and it would backfire and raise all kinds of havoc and is practicall immobile at this point.

Figured it was a carb problem, so I removed and cleaned the carb thoroughly, put carb back on........same problem.

I hate to say these words, but I have a friend who is very knowledgeable with Polaris repair, in which he repairs them for a living and he is stumped with my Yamaha. I also had him take the carb apart and clean it, just in case I may have missed something. Didn't help a bit.

It really backfires hard through the carb and doesn't seem to act the same everytime I try to start it. Sometimes it has to be choked and others it doesn't just to get it to fire and then it just throws a fit and dies.

Any ideas? Or suggestions where to start next?

Thanks!!
 

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like your polaris buddy, im stumped too ......

i was going to say it was a carb problem but i presume you checked everything ... was the diaphram ok or maybe your float is stuck or something.

Craig
 

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Discussion Starter #3
Thanks,

I couldn't find a thing wrong with the carb, and neither could he. I thought the float was stuck prior to any tear down, I had opened the drain on bottom of the bowl and nothing came out, I thought, ahaww! stuck float! found it!... so I tapped on bowl for spell and then the gas started to flow out the tube.....didn't help a bit, that's when I tore the carb apart the first time.

At one point when I was pushing it onto the trailer with the key on, I noticed the reverse light blinking, I figured that I didn't have the shifter all the way in neutral, so I just turned the key off and didn't think anything of it until I read more about the blinking reverse light on the forum. Although, it isn't blinking now. It almost acts like it's cutting out as if you where trying to throttle it up and the front dif-lock hadn't engaged yet, except it back fires through the carb profusely.

Can anyone direct me as to where the speed sensor is located on this machine?

Any further suggestions/ideas are quite welcome.

Thanks!
 

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Check the carb vent tubes and the gas tank vent tube. Might of had something crawl inside and make a new home.
Since you've torn the carb down I'd think you got all the connections nice and tight. It sounds like it's getting to much air or not enough fuel at idle. Maybe a bad gasket at the carb to intake?
You say backfiring thru the carb? Valve hanging open possibly? CHeck the valve clearance. Probably time anyways.

Im not sure where the speed sensor is but, if the rev limiter was engaging then you wouldn't have been able to get it to 55-60 mph at all.
 

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Discussion Starter #5
Thanks Hillbrigger. I'm still digging at it and haven't had a chance to look at it more since posting here, hopefully I'll get a chance to further diagnose today. I have taken notes and will apply everyones suggestions.

if the rev limiter was engaging then you wouldn't have been able to get it to 55-60 mph at all.
True.......thanks!

I'm going to have to keep digging.

Would valve adjustment just show up suddenly like that? Would simply needing adjusted instantly create havoc like that or would it slowly show its face in other ways prior to such a drastic backfiring? They have never been adjusted since it was new. Probably has around 1200 miles on it, but gets used practically every day.

Do they make a good service manual for these things? If so, does anyone have any suggestions as to where I can find one. The mechanical stuff and most electronics I can deal with, but I'm not real fluent in the computer control diagnosis department......and that's what scares me, that it is an electronic problem? :(

Thanks and any further help is greatly appreciated.
 

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Sounds like you are starving for fuel. I would pull the fuel **** and hose. Check it for debris or obstructions
 

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Also...not likely, but if you have a buddy who has a grizz like yours, plug his CDI into yours. Could be the problem as well.
 

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Discussion Starter #8
Thanks Grizzie,

It appears to be getting plenty of fuel to the carb. That was one of the first things I eliminated. So you think that CDI could react this way?

I have no such a buddy with Grizzly to try CDI, sure wish that I did. My Polaris repairman friend knows Polaris inside and out (which I think is requirement if you own one ) :), but he's kinda afraid of foolin' with my Griz, unfamiliar ground I suppose).

Does anybody know if valves needing adjusted would abruptly show up and start acting this way?

Thanks again!
 

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Your buddy's just afraid that if he gets under the hood, he'll start liking what he's seeing, and BAM! Another Ex-Polaris rider!

(And I'm one of them myself!)

I've got a good CDI unit sitting on the shelf. PM me with your address and I could send it out to you for testing...
 

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I would look at the valves. I think that is your problem. It could come on suddenly like you are saying if something is caught in one of them like A small piece of carbon not letting it close all the way. Also when you have the pull starter off I would look at the flywheel (timing marks) to make sure it has not turned causing the timing to shift.
 

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I don't know if the valves lash could be out of adjustment suddenly, but my intake valves were all too tight after 400 miles. As soon as I adjusted them I could tell it was much easier to start and ran quite a bit smoother.

Anyone know exactly how the decompressor works on the grizz? Maybe it's hanging open? I believe it only affects the exhaust valves though.
My little honda had the decompressor hang open and I believe it had something to do with a valve snapping in half. But that one has to flipped on by hand.
 

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Whats the compression at?
I think it could be valves or piston.
Sounds like the rings might be bad, and the fuel is going past the rings and and not burning. A compression test will tell you that if its bad or not. If thats not it whats the valves set at?

Decompressor is ran off the cam.
 

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Discussion Starter #13
Thanks a bunch fellas for everything, you've gave me some good ideas. Thanks BOB DENMAN for the offer, I may take you up on that, but I'm going to do some more in depth diagnosis first and try to isolate the problem.

I've got a service manual ordered to help me along and possibly keep me from any unnessacery work or expense. I should probably have one anyway, since I'm not planning on getting rid of the machine any time soon.

I know the valave are probably way past due on adjustment anyway, so I'll be taking care of that problem regardless as to whether it's the problem or not.

I use this Griz everyday and need it running in a bad way, I will apply everyones ideas and get back with everyone as soon as I figure anything out.

Thanks a million........to be continued......
 

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Thanks Jasson, knew the cam controls the decompressor, but can't tell from the pics in my manual how it actually works.

On my honda you flip the switch and a small lobe contacts the exhaust valve to open it up. On the grizz I see 2 weights on the end of the cam that look like they get flung outward but from there not sure what happens next.
 

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The intake valves on my 02 Grizz would get to tight from time to time.It would end up without any endplay at all.I would bet that the 3 intakes are all this way on your Grizz.Good luck
 

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Thanks a bunch fellas for everything, you've gave me some good ideas. Thanks BOB DENMAN for the offer, I may take you up on that, but I'm going to do some more in depth diagnosis first and try to isolate the problem.

I've got a service manual ordered to help me along and possibly keep me from any unnessacery work or expense. I should probably have one anyway, since I'm not planning on getting rid of the machine any time soon.

I know the valave are probably way past due on adjustment anyway, so I'll be taking care of that problem regardless as to whether it's the problem or not.

I use this Griz everyday and need it running in a bad way, I will apply everyones ideas and get back with everyone as soon as I figure anything out.

Thanks a million........to be continued......
I know it's has been a long time but did you ever figure this out I seem to be having pretty much the same problem. Same used winter and summer it was running fine then stopped went to start and it cranked and cranked then backfired. Now it backfires through the carb. When I get it to run and rev the reverse light is on so thinking it might be the rev limiter for reverse or when in differential lock. I changed oil, antifreeze and new plug and same thing appears to run OK at higher RPM but won't idle and when to go off idle to higher RPM it backfires and misses until it can get to higher RPM.

Hope you have an answer it is needed.

Thanks
 

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Hi everyone! I'm new here, have been lurking behind the scenes for a while, just now registered. Just so you'll know, the username has nothing to do with Polaris, it's from the TV show Rawhide, if anyone remembers that? :)

I have a 2003 Griz that I've owned since new, no mods, driven daily. Fired it up the other day, went about 100 yards and it starting backfiring, coughing, sputtering, just thowing a fit. Engine hadn't even warmed up yet. I changed the plug and that did not help.

It would start and run with choke on, smoke like freight train. With choke off it would backfire, spit, sputter and didn't want to rev without dying. With choke on I coaxed it to the road and ran it up to 55-60 mph. It didn't seem to miss a lick at high rpms with choke on. Prior to this problem, the choke would/should have killed the engine?

At high rpm's and 50+ mph, I could turn choke off and it would continue to run flawlessly until I let up on the throttle and it would backfire and raise all kinds of havoc and is practicall immobile at this point.

Figured it was a carb problem, so I removed and cleaned the carb thoroughly, put carb back on........same problem.

I hate to say these words, but I have a friend who is very knowledgeable with Polaris repair, in which he repairs them for a living and he is stumped with my Yamaha. I also had him take the carb apart and clean it, just in case I may have missed something. Didn't help a bit.

It really backfires hard through the carb and doesn't seem to act the same everytime I try to start it. Sometimes it has to be choked and others it doesn't just to get it to fire and then it just throws a fit and dies.

Any ideas? Or suggestions where to start next?

Thanks!!
Did you ever figure out this problem? I'm having the same issue.
 
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