Need Help

[SkidooKid91]

I have a 1991 Mach 1 617. I love this sled but I have a problem. It's really boggy on low end. It's boggy when I first give it the gas. Then once the clutch engages it's fast as hell. When I'm sitting at an idle I have to feather the throttle to keep it from dying because it doesn't want to idle. Then when I go to take off I have to feather it some more until the clutch engages and then it will take off and run like a champ. My dad has had the carbs off, went through them, and even changed them. Our cabin is about 6000 feet above sea level but all of our other sleds run just fine. It does it no matter when cold, hot, just started, ran all day. I know Machs are a ***** to start but that isn't the problem. It just wont idle nor take off good. If I just hit the throttle off the take off it will die. Thats why i have to feather the clutch until it engages and then once it does I can take off. Please help me! I'm going to take everything out of the sled. So I want to know what might be the problem!

 

[onlyrotax]

I'm no expert but I do have some experience to fall back on, try this. Everything has to work together to get a sled like yours to run at any sort of altitude, if the belt is worn or too loose it will ride up in the drive clutch when you take off, kind of like starting out in second gear, with the motor off push down on the belt with your thumb half way between the clutches, it should go down about 1 1/4 inches. Next make sure your float levels in your carbs are correct and needle positions are as specified, now you will need to know what size pilot jets are in those carbs(take them out and make sure they are not plugged also), they are the tiny little jets down in the well next to the main jets. If they are the stock pilot jets for sea level you will need to put in larger ones (probably 2 to 3 sizes LARGER, like from a 40 to a 50 or 55), your engine is actually starved for fuel coming off idle because the air is thinner at that altitude and less air coming over that jet means less fuel being drawn through the jet, if possible find a dealer that still has altitude specs for that sled and calibrate the carbs accorrdingly. If you doubt this try giving it a little shot of fuel with the primer as you take off see if it helps. Hope this helps.