Civic 99...you have been trying to tune this setup...and asking questions on ALL of the FL forums. NO DATA = NO ANSWERS. If you cant provide some of us with pics and/or measurements...we cant really help. Your setup is CUSTOM because of the sled engine transplant.
With CVT (meaning belt driven machines) clutch angles ALL have to be perfect FIRST. You must have a clutch on the trans that can handle the sled engine and belt width. (stock 350 will not just bolt on and work...spring too weak...belt wont fit either) If you look around at build pics...most guys use the matching secondary clutch for the sled they take the engine from. IF YOU DONT SIMULATE THE EXACT DESIGN FROM THE SLED...you may NEVER find a belt...OR clutch calibration that will shift your machine correctly. Resulting conditions are sounding like what I have scanned and read from your posts. (black smearing belt signatures on the clutch faces, low revs, crappy top end pull, etc) Sounds like you have the WRONG belt AND secondary setup to me.
Help us help you by taking some pics...show us what you got. Part numbers on the belt(s) you have tried are helpful too...
583 rave valve Ski Doo TRA primary clutches are setup to run a wider belt than the FL350...anything you bolt to that 583 that is made for that application will accept a wider belt.(108c 102c etc) Your FL350 stock/comet secondary clutch is made for a much more narrow belt. That IS a problem...you can spring that thing all day and it still wont be right. The overall diameter of the stock FL350 secondary is MUCH smaller than ANY sled secondary that has a 583 in it...these are just a few suggestions. The stock FL350 salisbury or even a comet 94c duster primary...are also MUCH smaller. (102c on an FL350 is like 1-2" larger than the OD of the others) THIS is why we keep saying you gotta 100% duplicate the sled's CVT design in order to make it work.