4 strokes make more low end (off the line) power and that helps in turning these machines and moving from the get go. Our max ll has a cheap 13hp honda clone engine 4 stroke from northern tool and pulls very well for only being a single range where we live. Mountains with steep trails. If its that big of an issue and the clutch spring already mentioned doesn't fix the problem a cheap 4 stroke would definitely solve your issues.
1983 max ll: Getting a 14 HP vanguard and some other custom mods.
1999 Arctic Cat 400 4x4: dvx 400 carb, msd 4217, kenda bear claw htr's.
2007 Kawasaki Mule 3010 Trans Diesel: Stock.
1997 Kawasaki prairie 400 4x4: Custom rollover bodywork.
1986 Isuzu Trooper II: Factory Diesel/5 Speed, 30+mpg daily driver.