I have 98 MXZ 670 that I was running fine @ about 90mph when the motor desided to seize on me. Tryed to pull it over and it was seized. towed it back to the garage and the motor now turns over good but wont start. Checked the compression and for spark and all checks out ok. It wont even try to fire over when I put gas in the cylinders. Can it have something to do with timing sense it locked up @ high speeds? Crank twisted or rotory valve? I checked the flywheel key and thats ok, I also checked the rotory valve and it looks ok. Can the gear that drives the rotory valve on the crank strip or jump a few teath? Any help would be great!!

take spark plug outs and pull motor over to check for rough spots. That must have been a wicked suprize haveing it sieze up at 90mph. i would say it might be time for a top end job to find out why it just seized on you.your sled should a plastic gears for your oil pump, you propbely striped it.

I checked for binding and it pulls over ok with the plugs out. took the head off and there are a few lines on the cyclnder walls but reall not that bad. The compression is ok only 5 psi of each other. Could the crank be twisted or the rotory vlave drive gear be stripped