Bought a couple of older exciter IIs. Cleaned up the carbs( mikuni) sleds run pretty good while engine temp is cold. Soon as they warm up they get boggy. Bad. Determined the crank seals were shot so I replaced them. Put about 4 miles on and right back to square one. Any thoughts? I’m a Polaris guy so not sure if I was missing something obvious or if Yamaha had a more common issue I wasn’t aware of. Appreciate any help.