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Hey maybe somebody can help me and chime in on this subject. I have a 2004 grizzly 660 my float valve was stuck over the winter and gas kept draining out of my overflow so I took the carb apart which I have done before for cleaning and replaced the float value and needle. When I Reassembled the carb and started the bike it started fine and idled like it should. However when I go to give it any gas it bogs out and dies. My slide and diaphragm are in perfect shape when the carb was disassembled I could blow into the top Chamber where the diaphragm is and see the slide move up and down with little effort as I force air in lightly. So I know it’s working properly but when it is installed on the bike and the engine is running I can remove my airbox and I’ll look into the throat of my carb and give it gas and see that the slide is not moving up. However when I hold my hand over part of the airbox intake somehow suction is making it rise that way but clearly I cannot keep my hand on that because my seat covers that when everything is installed properly. There are no tears in my diaphragm no holes I’m really stuck here I’ve had this car parked before for maintenance and cleaning I bought it new in 2004 so it’s been almost 15 years I’ve never had this problem it’s pretty easy to assemble the only adjustment is the air fuel mixture screw which has always been 2 1/2 turns out from a light seat. I clean the carb forfive times with carb cleaner I let it soak overnight and I sprayed three cans of carburetor cleaner in and out of every jet orifice and then blue high compression air from the compressor through every jet an orifice. I’m completely stuck here when I go to give it choke you have a throttle raises a little bit but I still can’t push my throttle in past a quarter without a bargain down. I bought a manual for this thing and when it was new and it was helpful but like I said you really can’t screw too much up with this carburetor because all the Jets get screwed in all the way until they stop except the pilot air fuel screw which is 2 1/2 turns I know where the main jet goes I know where the pilot jet goes nothing is mixed matched or reversed everything is exactly where it supposed to be I am really stuck here. Please help I really don’t feel like taking it to the dealer but I think I’m going to have to. All my valves are in spec. Intake specs are 0.10-0.15mm. Exhaust is 0.15 -0.20mm. I’m in the middle of those specs, my intake is set 0.13mm and my exhaust is set at 0.17mm. So I don’t know what else I could try. my diaphragm fits perfectly around the seat. I’ve done this before I don’t know what else to do please help!!!!????
 

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Check that the breather hoses are not blocked from something making a home in them at their ends.
The diaphragm can get pin holes in it that a visual inspection will miss, you gotta stretch & pull to show the hole.
The main nozzle can be put in upside down, it can also be crooked, jamming the needle, your carb has O-rings in odd spots, they all there?
Cracked rubber manifold taking pressure from the system, may have opened up when removing/replacing carb.
Blocked intermediate jet system, the other little hole/s other than the mixture hole, when guys blow out carbs they will remove jets then blow down the jet towers, any gunk gets blown towards the tiny jet holes in the venturi blocking them, the problem is that you can't blow these holes, only across them, you have to solder up the blower hole & drill another hole so the air comes out at a right angle, I have a Kawa 300 bayou doing exactly the same as yours, it was left for a couple of years & the fuel left something like chewing gum in the carb internals, got some out but it still has some in there, good luck with it.
 

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Check that the breather hoses are not blocked from something making a home in them at their ends.
The diaphragm can get pin holes in it that a visual inspection will miss, you gotta stretch & pull to show the hole.
The main nozzle can be put in upside down, it can also be crooked, jamming the needle, your carb has O-rings in odd spots, they all there?
Cracked rubber manifold taking pressure from the system, may have opened up when removing/replacing carb.
Blocked intermediate jet system, the other little hole/s other than the mixture hole, when guys blow out carbs they will remove jets then blow down the jet towers, any gunk gets blown towards the tiny jet holes in the venturi blocking them, the problem is that you can't blow these holes, only across them, you have to solder up the blower hole & drill another hole so the air comes out at a right angle, I have a Kawa 300 bayou doing exactly the same as yours, it was left for a couple of years & the fuel left something like chewing gum in the carb internals, got some out but it still has some in there, good luck with it.
Agree with all of this. and will add this my weapon of choice in cleaning carbs.

Blow your carb apart get in truck go to Walmart grab tupperware dish big enough to fully immerse the carb in liquid. Now walk on over to floor cleaning supplies and grab some original PINE SOL, no not joking.
Take that all home and toss all your carb parts in there..with the Original PINE SOL. let it soak for 5 ish hours, scrub with a toothbrush, dip into s pail of water to help rinse off, and blow with air, use a little carb cleaner(less then 1 can usually) the pine sol will get to all the parts of your carb you cant see and eat the gunk blocking passages. Since I have started doing this I never have issues.

KEEP in mind the pine acid in the Pine sol will remove finish of carb and brass parts so they will no longer be "shiny"
 

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I know I am waking up an old thread but I hate to see one with no end and find many here that just trail off into nothing. I'm only going to add that any carb that sat for a year or longer with gas/gel in it needs more than a blowing out with air and some squirts of carb cleaner. Berryman carb cleaner in the chem dip can with the basket is about the only way you can assure you can clear out all the ports in a dirty carb. Not as nasty as 30 years ago and so not a quick either, leave stuff in the basket to soak overnight but it will clean your carb.
 
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