gy6 confused!

[junebug]

Hey guys Ihave a sunl 150 buggy with a gy6 short, something happened to where my top end isnt moving. The timing chain is not broke, it acts like the gear on the crank is moving. Anyone heard of this? thanks all

[SYCARMS]

I'm confused, are you sayong the crankshaft turns but the valves don't ? Be more specific if possible.

TOM

[junebug]

yep, the crank spins over without the chain moving. I pulled the cam out to move the chain and it just spins on the crank. Could it have came off the crank gear or is the timing chain crank gear keywayed? Thanks any advice deeply appreciated

[GX150]

I believe the timing chain jumped off the the crank gear. The only way this will happen is if the tensioner is broken or loose. Shine a light into the case and see if you can make out the gear and chain. If you cannot, you will need to pull the head and possibly cylinder to see what is going on.

[junebug]

I'll give it a try, wonder if i pull the cylinder off if it will even be acessable then? If it did come off the crank gear would it bend valves?

[SYCARMS]

Pull the head and cylinder then look down the case using a mini flashlight so you can see.Make sure the chain is on the crank sprocket. It will look like 2 sprockets on the crank, the chain should be on the outer sprocket. The inner is an oil splash. A bad tensioner or stretched chain will cause it to come off the sprocket. To check your valves while holding head strait and level spray some light oil like penetrant oil or carb cleaner down intake and exhaust runners just enough to cover the valve itself. Now look on the underside at the valves still holding head level and upright to see if they are leaking.

TOM