Honda pcx 2013 Engine seizing up?

I am currently using a friends honda pcx it cut out a couple days ago and I thought the starter motor went because it wouldn't crank over today I took it apart to check what's wrong and the crankshaft was seized in place I cracked it out of bring stuck and the bike started quite nicely then after about 30 seconds seized up again... did that every time I unsiezed the engine.. I am going to rebuild the engine before giving it back to my friend but just wanted to know what the most likely thing could be.. I have a rough feeling it's crankshaft related but I'm not sure what the 3 sprockets on the crankshaft are and wondered if there could be something jamming do do with the sprockets.. anyway I'll be fixing it either way and my friend doesn't mind about the bike as he's been letting me borrow it for around 6 months now... anyone know what it could be like oil pump or anything??
Answers

Candid Chris

Usually the crank main bearings seize due to lack of oil OR abuse so pick one.

Old Man Dirt

This is a four stroke motor and as such requires oil in the crankcase. Some one might have thought it was or is a two stroke and treated it as such. I never reuse a crankshaft that has seized unless it is turned and fitted with new bearings. Care needs to be taken when putting the bearings back in to make sure the holes line up for oil distribution. Use the right bearings for the turned crankshaft! I suspect that the failure to get the crank shaft resurfaced caused the second failure. Remember to pre-lube the bearings. Make sure the crankcase oil level is right!

Anonymous

Do not guess. Just tear it down and find the bad parts. Get a caliper. The bearings are most likely shot. These bikes are almost bullet proof but a lack of oil or oil changes kills all engines. The oil pumps on these bikes rarely go bad.