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Discussion Starter #1
Hey everyone I'm having problems with my 02 660 grizzly. It will not stay running after initial startup.

My grizzly has sat for about 7 months but it didn't have fuel in it as my gas tank was leaking fuel and I took the old tank off and replaced it with another used on. Before o put it back on i cleaned it out really well and everything.

I also have replaced the spark plug and spark plug cap. Put a brand new carb on, new air filter box (upper & lower), new air filter and new rubber grommets from the motor to the carb and the carb to the air box. Pretty much everything on the top of the motor to the air filter are all brand new.

I put brand new premium gas in the tank, opened the choke, pumped the throttle once to get some gas in the carb and hit the start and it fired right up and was idling fine, reed it up a few times and it would idle down. But after the motor warmed up it cut out and stopped running. Opening the choke wouldn't even start it again. The only way I could keep it running was by holding the throttle down slightly and hitting the start button and it would fire right up no questions asked and keep running till I let off the throttle. And every now and then it would seem that it would back fire after high reving or barely pressing on the throttle. But anyways it just want to stay running and I need to get it to stay running and stay running after I sell it.

Any suggestions or help would be greatly appreciated. Thanks again
 

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You may need to raise the needle a notch or two if there is no slack in the throttle cable.
How is the A/F screw set?
 

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Agree sounds like the carb. If it back fires more than likely carb needs adjusting, new carbs still need final adjusting.
 

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Discussion Starter #5
the a/f screw is capped to where i can't adjust it and the throttle cable adjuster i found was wound to its max and still wasn't even touching the throttle body, so i swapped out the old one from the old carb and put it in the new carb and now it touches the throttle body. i adjusted it enough to push the throttle back a little to open it up just a hair. And my carb came with 2 additional pilots i believe a 1.50 & 1.55 not sure whats in it now because it is capped and sealed. It ran for a minute when i adjusted the throttle body screw then started backfiring really bad.
 

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Discussion Starter #6
This is the old carb and as you can see the a/f screw is not capped. but on my new carb there is a metal cap with 2 tiny holes in it covering the a/f screw up and i have no idea what to do
 

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Discussion Starter #8
The EPA makes them cap it. I'm yet to see one that can't be removed
i've heard of people drilling out the cap but i was kinda hesitant on doing so for damaging the pilot underneath
 

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Why did you replace the carb in the first place? Was it dirty or giving issues?

If possible clean the old carb and reinstall it. I suspect it will work better than the eBay Chinese special you installed.
 

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Discussion Starter #10
Why did you replace the carb in the first place? Was it dirty or giving issues?

If possible clean the old carb and reinstall it. I suspect it will work better than the eBay Chinese special you installed.
didn't buy a ebay chinese special carb. I paid nearly 200 bucks for this damn thing. Plus the original carb that was on it was on its last leg and was giving me more issues than i wanted to try and rebuild it for. plus the original has long since been trashed by about 2 years ago. the one that was in the picture was its replacement and then this new one i got is giving me the same problems as the one in the picture
 

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What carb did you buy?
Was the old carb you took off a factory Mikuni carb?

After re-reading your original post, I think you need to adjust the pilot needle. You need to lean it some (turn it in). When your bike first starts the engine is cold and can handle the extra fuel (like having the choke on, which is an enrichening valve). Once the engine warms up, the engine is running rich and floods out at idle rpm. Adjust the pilot needle in 1/8 turn at a time and see if idling or low rpm improves.

To get the plug out, drill a small hole in the plug, then put in a wood screw and pull the plug out.
 

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Take Dezz's advice with the pilot plug, drill slowly till you feel the drill bit start to break thru the plug then stop, insert wood screw or self tapper screw, you can also cut the point off the screws if you feel it might touch mixture screw. I'd check the jet sizes also, that you had to use an old part on a new carb to get it to work doesn't sound right, the carb might be the same but for a different type of motor or from a bike & has different jets.
Another thing to look at is the plug lead it'self being jammed between the tank & the frame(they LUV doing it!) & rubbing thru arcing out causing a back fire.
By the way is this problem a back fire thru the exhaust or a spit back thru the carb?
 

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tag. Similar issues.

New to forum, new to Grizzly, gift from a friend. 2001 YFM600 with 602 miles on it, has been sitting for at least three years. Degunked tank, replaced plug, removed mouse nests (seriously), pulled carb and cleaned/reassembled, had engine running last night but wouldn’t idle well, some “missing” and occasional backfiring (carb AND exhaust).

Tried again today, ran a boatload of Seafoam into carb after getting it running again - but ONLY with choke on full - now it’ll run, and idle a bit better. Think a passage or jet might still be clogged, narrowed, but I like these old mikunis; been about 30 years since I worked on one, had yamahas in the 1970s, a Norton commando 850 I put a Mikuni on for a while. Parts are big enough these old eyes can still see ‘em.

I got an “OEM” parts/rebuild kit in the mail today, I’ll pull the carb again, clean, replace, and see what happens next.

Great forum, I’ve been lurking for a couple of days now (just picked up the ATV on Sunday, tore into it yesterday AM, changed oil, etc.), thanks for any answers/suggestions, hints/tips.

Seems like there’s a boatload of aftermarket (ie. cheap chicom knockoff) parts (CDIs, coils, magnetos, voltage regulators, carbs, etc) on ePay and amazon. I’d like to keep this alive for a few years yet, use it on my farm in TN when i finally retire there.

Got a ‘92 HMMWV 6.2L NA diesel I’ll be using around the property too, ATV’s easier to get in and out of the garage and on some trails I might need the HMMWV’s hydraulic winch to pull out of.

Thanks again.

Norm
 

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tag. Similar issues.

New to forum, new to Grizzly, gift from a friend. 2001 YFM600 with 602 miles on it, has been sitting for at least three years. Degunked tank, replaced plug, removed mouse nests (seriously), pulled carb and cleaned/reassembled, had engine running last night but wouldn’t idle well, some “missing” and occasional backfiring (carb AND exhaust).

Tried again today, ran a boatload of Seafoam into carb after getting it running again - but ONLY with choke on full - now it’ll run, and idle a bit better. Think a passage or jet might still be clogged, narrowed, but I like these old mikunis; been about 30 years since I worked on one, had yamahas in the 1970s, a Norton commando 850 I put a Mikuni on for a while. Parts are big enough these old eyes can still see ‘em.

I got an “OEM” parts/rebuild kit in the mail today, I’ll pull the carb again, clean, replace, and see what happens next.

Great forum, I’ve been lurking for a couple of days now (just picked up the ATV on Sunday, tore into it yesterday AM, changed oil, etc.), thanks for any answers/suggestions, hints/tips.

Seems like there’s a boatload of aftermarket (ie. cheap chicom knockoff) parts (CDIs, coils, magnetos, voltage regulators, carbs, etc) on ePay and amazon. I’d like to keep this alive for a few years yet, use it on my farm in TN when i finally retire there.

Got a ‘92 HMMWV 6.2L NA diesel I’ll be using around the property too, ATV’s easier to get in and out of the garage and on some trails I might need the HMMWV’s hydraulic winch to pull out of.

Thanks again.

Norm
Welcome aboard. Lots of information to keep that bike running for years yet.

Some members in here also have experience with the H1....me included. I have done lots of work on a 1998 model with the 6.5 Turbodiesel.
 

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Welcome. I love working on grave yard ATVs..lol Rebuilding a carb is not to big of a deal, I have learned to get a manual helps a lot.
 

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When I was 13, my brother - a Harley owner/rider from early on - gave me a Yamaha twinjet 100 frame, wheels, and two engines complete in a couple of orange crates. And a Haynes manual. “Happy Birthday.” Took most of a year to get that fired up and I rode it around for a couple of years.

Got the factory service manual with the Grizzly. I also printed out the Yamaha service data, and owner’s manual from their website (found a workaround to printing their PDFs).

Service manual is a bit “thin” in the breakdown/teardown/reassembly of the carburetor. Reminds me of my Army days, yanking a broken part and replacing with one off the shelf or out of depot.

I’ll keep y’all posted. Thanks for the encouragement.
 
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