Sounds like you got it figured out. We'll see if the new belt lasts or not, if so, cool!
I still don't like the white spring at all. It's really designed for the less powerful stock engine. It's kinda like giving your cart 4:56 gears instead of 3:07 gears. Not sure you know what I mean or not. Basically, it keeps the trans in "low gear" for longer. This is good with a stock engine that only has 9 horsepower, where it needs the torque to climb hills or pull a load.
What you have is a 22 horsepower engine, Vtwin at that, that makes 3x the torque of the stock engine. You don't need the white spring to help with torque, you have plenty with that engine.
Big blocked carts usually do much better with the stock secondary springs, at least Yamaha carts do. It will shift much better and get up to speed faster. It also will put less pressure on that belt.
Typically with a "power spring" like you have, you'd want to use a HD kevlar type belt that will withstand the extra pressure and heat that spring will make the secondary produce. I'm guessing that's why the belt shredded?
Oh, almost forgot....those marks on the clutch center shaft....Pipe Wrench teeth....
