In the words of Jase Robertson .... "don't make me out to more than I am!!" I just have some buddies that are amazing, and I have tried to pay attention real closely. I am about as mechanically inclined as a Dukes of Hazard lunch box.
The set up is what I would call old school. It originally was started by Bill Lofton. Little snowmobile history lesson, if you don't know who he is. He was the first person to do a drop and roll.
Twister and I messed with it for 3-4 years, tweaking this and that. We have always wanted sleds that feel like big bores. Its a super linear pull. IMO it flat works.
I don't have your exact sled, I have your sled but with a carb motor. I run 56 or 58's depending on the snow conditions. 56's give me the bottom end I want, but the 58's have the, you better have your big boy pants on pull.
Originally Bill called for 60's. It would pull RPM's. but it just seemed lazy. One weekend we did some extended testing. We tried everything from 68's to 54's. From 56 to 60 the RPMs were real close. It would just pull differently. Once we dropped to 56's, the sled asked for more fuel and really lit on the bottom.
IndyDan has now taken the set up, and tweaked it. I think he has really done what we didn't have time for, perfect it.
Controller, I don't have one, well I do, its called power jets. I am not a big fan of the dobek controller. We have thrown a ton of them away.
Jskattum... its not that I know anymore than you. Its just those springs wouldn't work for me. Maybe partially personal preference. That orange spring engages so high, it drove me nuts.
As you stated fuel is a huge creator soggy bottom end.
Hopefully this helps and I am not just rambling. I am a little tired tonight.
