throw in a new set of plugs to start out with. if that doesnt fix it then there are a few other things you can do.
take the carburators off and dont mess with the adjustments and if you do make sure you mark and put them back together the same way you took them apart. clean them out really good. check your fuel filter too. if they are plugged then it will draw fuel but not under load.
if the carbs are clean and you still have a high end bog it could be your jetting. if the jetting is making it run rich you will flood out the sled when you full throttle it.
try the plugs. im sure thats probably it but with snowmobiles there are so many variables.
I doubt it is the jetting unless the jets had been changed at some point, or just plain clogged....new plugs and/or a very throughal carb cleaning.
My money is still on fouled plugs getting too much fuel at full throttle to burn it all...get to "full throttle" where the sled bogs, hit kill switch and coast to a stop...take out plugs and I bet they are dripping with fuel.
My old '91 Wildcat would idle with fouled plugs, was good till about 30-40 MPH, then flat...
NEVER hit full throttle and kill and coast to a stop. thats how you bend rods. did it once on a 98 skidoo 600. what you do is throw new plugs in it and start with that. if the problem is solved then dont worry. if it still does it clean the carbs good.
tonite i just did needle n seats in my 650 and when i took the carb apart there was this jelly like stuff in it and i went to a shop by me and they said it was ethenol that is in the gas and it jells up when it sits for long periods of time. clean your carbs good and use a blow tool with an air compressor to blow out all the jets and holes in your carbs.
by the way guys in any small engine class and manual they will tell you to go full throttle and kit the kill it is called "imaging" the plugs its one of the best and really only ways of telling how it is running fuel wise. and it does sound like the main jet in the carbs is cloged, its the one in the middle where the bolt/jet that holds the bowl on is.
I guess I stand un-correted...it is a method used on "tuning" motorcycles (indexing spark plugs) so I figured it would pass on to sleds too so I offered the advise, and for the life of me, I could not figure out how a rod could get bent doing this on a snowmobile. Once the RPM's drop, teh clutch opens so there would be no drag from the track..that being said I'm open and welcome any explanation why it would damage the engine??
How would it any different from the sled running out of gas at full throttle, hitting the kill in an emergency at full throttle, or having a sled with a "tether" and falling off at full throttle? I could see big issues with eteh sled maker if any of these resulted in engine damage.
Back to the question...looks like a good carb clean and some new plugs will take care of the issue.
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