Oh. Well then.... sand will load your bike very hard and put a lot of strain on clutch. My 421 i was referring to were hill climb bikes and i never got out of 3rd gear. Dune riding your usually in higher gears making it harder on clutch. Like i said before, I personally would get a clutch kit from redline and try that. If it dont hold, you can always add lockup/cover. If you were only riding only dirt id say you could have 400 hp and not run a lockup.