HELP!

So I was out riding this morning cruising at about 35mph in 4th gear when the engine shut off. I was unable to restart it and pushed it home. I have intake, exhaust, cam, tune, 14t sprocket.

No signs of any kind of catastrophic failure preceding or after this. No leaks, no smoke, no bangs, no grinding.

Got the bike home and I can easily overcome engine compression and push it in 1st gear.

Bike is making a strong spark, no reason to suspect fuel pump problems. Recently did my first oil change with full synthetic. Bike has 1100 miles and I was not riding hard when it failed.

What happened? I plan on measuring valve clearance again but the locking nuts were still tight when I got it home. What are the chances my piston rings are gone? Aside from getting an engine compression gauge, what else can I troubleshoot? No apparent leaks from the spark plug or head-gasket, all engine covers are snug and in place.

Looks like a high compression piston may be in my future after all.