Hisun Vector 500 Lower Timing Chain Sprocket

[Texas Rider]

Okay guys, this Vector 500 is killing me. Hisun 500cc engine (Chinese)  About a year ago while riding slowly, I heard a tink and UTV turned off and would not start.  Checked everything long story short, timing chain jumped off lower sprocket, slightly bent the cam sprocket phasers.  Bought new chain and cam sprocket, set everything back to timing position, mounted chain on lower shaft sprocket and upper cam sprocket.  Set the tensioner, cranked and poof, chain once again jumped off lower shaft sprocket.  Again, repeated proper timing settings, remounted chain, cranked and poof again and again and again, chain keeps jumping off lower sprocket.  Just to be clear, valves, piston and all components are look in great condition.   Can't see shaft sprocket but to the finger behind the tight squeeze, all sprockets seem to be in place, or maybe not.  Tired of fiddling with it. This was bought brand new at Home Depot and has less than 200 hrs in the past 3 years.  Don't tell me to warranty it as that expired one year in. Talked manufacture out of McKinney TX and service tech was no help.  My question to you, what am I missing? What next?

Dumbfounded 🤔

[Travis]

do you think its possible the shaft could be out of round or bent?

[Texas Rider]

Unlikely that its bent.  The crankshaft is too narrow as you can see on pictures. The sprocket is pressed in and the hours are under 200. No reason for that to bend. Hisun suggested new tensioner and tensioner guides but even those look brand new. 

[N. MI Living]

Ever get anywhere with this? I’m having similar issue, engine jumped timing and won’t run. I can spin the cam, the timing chain turns, but the crankshaft doesn’t. I was actually able to screw around and get everything longed up again and got it to run for 10 seconds. Everything looks new, that I can see. Worried gear on crank issues. Only 4 years old and couple hundred hours on it. With it being a press fit, I’m thinking no way to replace with engine installed. Hope you got yours running again. Mines been down for a few months and momma wants it back running. Maybe I’ll just drop a 5.0 coyote in it. Lol