Switchback cease after top end rebuild

[Mitchell424]

I rebuilt my 2012 polaris switchback 600 top end after low compression. Followed all instructions and put oil in gas and idled for about 20 minutes before riding. Got down the trail about .5 of a km and it ceased. Towed home and starts first pull now but has check engine light? Anyone know what’s going on?
Thanks

 

[BeartoothBaron]

Sounds like a "four corner" seizure. Usually you see that when you run a cold motor too hard, but if it was idling that long, the pistons would definitely have been warmed up. That said, 20 minutes of idling could be enough to start overheating... One other possibility is it was getting hot when you started riding, then got a slug of cold coolant before the thermostat caught it - would cause the cylinder to shrink quicker than the pistons. Not sure what would cause the engine light, but it sounds like it's going to have to come back apart. What kind of pistons or kit was it?

 

[whoisthatguy]

The oil injection port inside of the carburetor, if it has one, could be plugged with some solidified oil. Blow out the port with compressed air. If the pistons were installed backwards, then the piston ring ends with abut over the exhaust ports. Which will quickly cause piston seizure.

 

[ditch1000]

How much end gap were on the rings when your installed them? You usually need 0.018” to 0.025” end gap on all rings..