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Hello all. First time poster here I've recently purchased a frankenstein'd 03' rev 600 with a 440 swap for 1000$ this past summer! In the excitement of snow in my area I have taken it out for the first time. Sled starts up great and idles but under load it will bog/hesitate around low to mid rpm clear itself out and high rpm run fine. Its to be running incredibly rich aswell. Lots of gas/oil in the intake box. I have inventoried all the info I can so far from the carb breakdown as follows.

440 engine L/C dome
Main jets: 290
Pilot jet: 22
Needle jet: 04 trail needle (6EHY2-59) at the very top clip
Air screw: 1 3/4 turn
Idle screw: have not messed with sled idles fine(imo)

Im stumped I've read all through the jetting database and from what I have gathered from the carbs the sled shouldn't be running poorly at close to sea level at -10.
Any help would be appreciated or maybe there is something I'm missing. I've verified that it in fact has a 440 mpem and carbs. Compression is 130psi on both cylinders. The snowmobile is a bit of a Frankenstein and does not have a original 440 clutch. Maybe that is what is causing the hesitation/bog??? Clutch inventory as follows

47/44 helix
228 ramps
Black primary spring
Clickers set to middle of clutch

Gearing of sled is 19/43

Again any help would be appreciated this is all the info I've gathered from the sled so far and at a loss on why it is running so poorly. Will attach photos if needed THANK YOU!!!!
 

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If over fueling?

I would replace the needle & seats. The needle wears inside the bore of the seat from vibration and over fueling occurs when running.

Check the reed peddles as well for cracks or chipping.
 

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If the slides are worn that bad. I would install new needle & seats for sure.
 

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Discussion Starter · #5 ·
Will do. Just ordered a complete rebuild kit for the carbs including needles and jets. I'll report back If it resolves my issue (fingers crossed the snow is here)
 

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Use genuine Mikuni parts if possible. The jobber jets sizing is way off. I have had all kinds of issues with kimpex jets over the years.
 

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Discussion Starter · #7 ·
Went to the dealer attempted to order new needle jets. Doesn't seem like you can order them from bombardier anymore?? Unless the parts advisor doesn't know what to look for? Anyway I ordered genuine mikuni 389 series q6 needle jets which seemed they would be correct from the 04 race manual. But they do not seem to be the correct needle jets. Could anybody guide me on ordering a set of needle jets???
 
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