Well my brother and I fixed a old 87 bayou 300(new rings,battery and starter,fixed the brakes) for an old farmer. Well after we fixed it we rode it around to make sure everything was fine, and when we gave it back it was. But he came back a couple weeks later and said he says it wont run, so we bring it back here and we look at it, the battery was completely dead, only reads like 3V. When jumped it would run over but wouldn't start and seemed extra easy to turn over. The old farmer said it was making a scraping noise before it died. So we took off the top cover to look to see if the cam chain was still there, it was but the sprocket on the came wasn't tight so when it spun the cam didn't turn. So i fixed that, reset the timing etc... So i tried a compression tester on it and i got 0, i've never got 0 before, like even if he ran it wipe open in 1st after he got it back, wouldn't i still get more than no compression? I'm just gettin frustrated and nothing is making sense. Please help

 

If the cam wasn't turning over when the bottom end was, you bent a valve(s). The valve hangs open and the piston falls in love with the valves. WACK!!!!![img]i/expressions/face-icon-small-happy.gif[/img]

 

but thats wat i don't get, if the cam isn't turning, seems to me like without pressure holding it wit the valve open it would turn to where theres no pressure from the springs against the cam, so the valves would be closed, like a valve being bent would explain the no compression, but hwo could it bend is what throws me off, how can it hang open?

 

there is a couple of ways the valve could hang up, it was cold and hard to start so he sprayed ether in it and it dried up the oil lubing the valves and they froze up in the head, or it sucked some cold air up in there while it was hot and bent them, that can happen if there isnt enough pipe on it, it didnt get enough oil and they stuck in the head while running and it bent the valve OR the pushrods unless its and over head engine them it would just be the valves, but if he busted a hole in the piston them he would definatly heard that one!!! and it aint no scrapin sound it makes either! lol, thats a boom so to speak. or you may have just set the timing backwards and didnt realize it so the exhaust valve is open an you just dont know it?

 

It is also possible that when the cam started slipping independently of the sprocket, the cam timing got way off which brought the valve into the piston. Now the cam won't turn at all.

To be honest, I have never heard of a cam spinning independently of the cam sprocket before...........