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Discussion Starter #1
Top end is on the sled rips bottom end is pretty poor had new 310 main jets and new neede jets carbs spotless. stock the sled runs 290's but the original owner jetted 310 after he removed all of the baffles in the pipes and mufflers. should i re jet the pilot jet up or down a size? or maybe the mains are a size too big i replaced the exhaust manifold boots tonight


mikuni aw38 carbs 310 mains on a 1991 arctic cat ext 550 i typically sled 15-25* ferenheit
 

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After u make a wide open pass with it what do the plugs look like ??? and is there any hesitations ??? I dont know much about efi but carbs are alittle easier for me lol
 

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Discussion Starter #3
didnt check tonght although that was next on my list. i do know that they were never hot or fouled so its gotta be darn close on the carb jetting/tuning
 

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Discussion Starter #5
ok pully side plug looks good ceramic is whiteish plug looks mostly new the other plug looks darker but not qute fouled. i should probably just replace my ignition module since i have a brand new one sitting here as a spare replace both plugs test then if it still bogs remove the belt to see that its not clutching problems .
 

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ok pully side plug looks good ceramic is whiteish plug looks mostly new the other plug looks darker but not qute fouled. i should probably just replace my ignition module since i have a brand new one sitting here as a spare replace both plugs test then if it still bogs remove the belt to see that its not clutching problems .
its definitly worth a try :)
 

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Do plug chops at idle, mid-throttle and WOT.
You can be good at WOT and even mid, but fat at idle.
Pilot jet is for idle and up to 1/4 throttle.
Slide needle is for mid-range and main jet is for top end.
 

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Discussion Starter #8
yeah the chops are perfect at mit and wot the stator side plug was wet and looked a bt more oily than expected at idle wondering if the oil pump is being goofy at idle , but i do need an adjustment on the air screw for idle. but to be clear my vm38's have the air screw on the airbox side of the roundslide when installed. so with that said (since front and back of the carb is unclear in the how to posts) do i screw it in to lean or screw out to lean.
 

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Just curious, do you have a y-pipe and single resonator? or dual resonators?
mine has duals but can't seem to find any parts manuals that show this, all decals have been removed.....
 

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Discussion Starter #10
mine does have a y pipe for the exhaust manifold. then it has one tuned pipe/resonator that empties into a box style muffler
 

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Discussion Starter #11
Just curious, do you have a y-pipe and single resonator? or dual resonators?
mine has duals but can't seem to find any parts manuals that show this, all decals have been removed.....
go to babbits.com thay have parts lists and blow up schematics for nearly every year and every model part for part for your machine
 

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Discussion Starter #14
deffinately discovered the real problem today when i had a belt shred on me. two broken motor mounts but the clutc looked alligned when no torque was on it but the motor would rock and move the clutch out of allignment during loaded situations.
 

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Motor mounts are definitely a problem on that sled. I was running at WOT when mine went. The primary came back and hit the secondary. That makes a hell of a noise at 80 mph. I ended up using a ratchet strap to pull the engine back down and rode it in like that. Primary had a hell of a groove cut in it.
 
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