Help with no compression on suzuki LT230 quad!

Hey everyone I just bought a 1991 suzuki lt230 quadrunner last night for very cheap, like 200 bucks cheap. This is a 230cc overhead cam 4 stroke engine with semi auto trans.

previous owner states that it has no compression, hence the cheap price of 200 bucks. This quad is a pull start, and electric start. I pull the spark plug, and yank the cord. Engine spins freely. I seal my finger over the plug hole, pull the cord and what do you know, engine spins freely! Ok so no compression

Next, i yank the two access plugs out of the valve cover that allow me to do a valve adjustment and see the valve springs. So, i pull the cord again and wait to see the valve springs go up and down and guess what?? they magically do not move at all, perfectly still while the piston is going up and down!

This cam has a gear on it that is driven by the crank with a chain connecting everything. I HOPE that the chain is just broken which is why the cam is not spinning and actuating the valves. My question is what are your all thoughts on this? Can the valves be open based on whatever position the cam is in, causing no compression?

heres a few pictures of the disabled beast...

 

Here they are, a chance to show off the truck too!

 

Valve open = no compression

 

Yes, and as the only cam position that has both valves closed tightly is at TDC on the compression stroke, and probably just 4° or 5° of rotation, it is quite likely that the can is NOT in that position...

 

I'm assuming you have checked that the piston is still moving up and down. I could be wrong but if both valves are closed, and you cover the plug hole with your thumb, with the piston at top dead center you will get vacuum on the down stroke and a return to normal atmosphere on the upstroke. You could have a open valve, a hole in the piston or major leakage past the rings etc based on your thumb test results.

 

i can see the top of the piston and it does not have a hole in it. Now im wondering, if my timing chain broke, wouldnt that be the only way really that the intake and exhaust valves wont move when my pistons is moving up and down. and if that is the case, im wondering if having a broke timing chain did anymore damage? if its just the timing chain, the rings may be okay. would be lucky if i didnt have a bent valve or if one touched the pistons if they are indeed in an open position

 

However the OP reported the cams are not turning indicating a broken timing chain/tensioner/sprocket/?. It is a thumper so the odds of the camshaft being positioned so that both valves are closed are not good, as stated above...

 

yea at first i figured it need a new top end, rings pistons, etc....But....the valves are not moving when the engine cranks which obviously is a massive problem. i have to pop the valve cover and see whats going on. how would a broken tension figure into the valves not moving? wouldnt there just be slop in the chain?

 

Valve damage with a non-rotating cam is dependent on the engine's being an "interference" or "non-interference" design. In the former the piston can hit an open valve, in the latter not. Bad news is that as far as I can find the LT230 is an interference engine--but that doesn't mean the piston did hit a valve just that it could...

 

Yes, that or a bad sprocket(s) would likely still rotate the cam to some extent--but maybe not, depends on the engine...

 

Tear it open - bet you find a broken or slipped cam chain.

If you're lucky only the tensioner failed, and it just jumped off the sprocket.

Suzuki thumpers are pretty bulletproof but the cam chain tensioner is a known weak spot.

 

Thanks man I didn't think of the chain jumping off the cam sprocket. Now I'm very hopeful that's all it is!!

 

Ok guys I got the side cover off the engine. The timing chain was laying behind the flywheel. I was able to pull it out with needle nose pliers. It is all in in one piece beside one small sleeve one of the links goes thru. I will need to remove the flywheel in order to put a new chain on, any ideas on how to get it off?

Also, why exactly do you guys think the chain snapped?

 

I used a chain breaker/press on the cam chain when I rebuilt my KTM 4 stroke. I had to remove the fly wheel for some other maintenance and it required a special puller. My guess is the chain stretched beyond spec or the tensioner is worn. It derailed and got jammed behind the spocket and that's what broke the link.