Hoping against hope that you will tell me that my '86 225 Moto4 is not as bad as I think

[DaveswMN]

Pulled my '86 Moto4 out of shed where it sat for 20 years. I knew it smoked. checked it over a little put in gas and it fired right up!! 

Drove about 100 yards, ran about half throttle wouldn't idle.  Put on somenew parts, jug/piston and rings, carb and valve seals.

'went together ok, tuned it over by hand about 6 revs whick went well. Hit the starter it fired for about 6 revs and quit. tried it again fired once and then th sound of something slipping like maybe chain slipping over spoket.

Took cover off to watch cam sproket, hit starter again, heard same noise and the cam sproket was not turning but jumping a bit. Chain was still tight. You will probably tell me I need to split the lower case but hoping there mightbe something else.

I don't fully understand the chain tightener, the plunger only moves about 1/4 inch, should it move much more than that when off the motor and compressing it by hand?

Thanks for any thoughts.

[Mech]

It's sometimes possible to remove the tensioner, drop the cam sprocket off the cam, let the chain off so there's more slack, then try to get the chain to go back on the bottom sprocket by manipulating the chain, possibly with a length of stiff wire down the hole levering the chain over. Then put the chain on the top sprocket, lift it onto the cam shaft but don't put the bolts in, check and redo the cam timing being careful not to bend any valves, then assemble it back up. If you can't get the chain on the bottom sprocket then yeah, you take the side case off again.

Stateing the obvious perhaps, but, you have to check the cam timing with the slack taken out of the chain and all on the tensioner side.

I'm not sure how much travel the tensioner should have, but it needs to be enough to take the slack out of the chain. It would be a good idea to figure out why the chain slipped. The tensioner has a ratchet mechanism, visually check the teeth  and pawl of that, and test it lightly, with big pliers perhaps, but only gently.. The other thing that happens is that people don't get the two slippers sitting in the correct places at the bottom, or even up the top on some models. If/when everything looks and tests ok then put the tensioner back in and turn it over..

[Gwbarm]

It sounds like the chain may have jumped off the crank gear, take the cam sproket out and see if you can reposition the chain back on the spoket.

[DaveswMN]

Pulled the cover,stator and fly wheel and found the chain off the sproket. Replaced, timed turned by hand. doesn't seem to have much compression. spun it with the starter and did not start. Checked the tappet gap and found them to be off from what I had set originally. Haven't been back at it but seems like I might run out of threads when I get back to adjusting the intake valve. Both vales seemed to be operating ok by looking thru spark plug hole. Hope to get back at it in a few days.

[Gwbarm]

Is your tappet gap tighter or looser and on both valves, tighter or a bent valve would explain low compression.

[Mech]

You've got a bent valve or two preventing the valve from closing right down onto it's seat, and that's why the valve clearances have opened up and why there's no compression.

Head off again I'm afraid.

[DaveswMN]

I'm suspecting now that a valve is bent. If when I originally turned the engine over and it fired for about 4-6 times I heard something. If the chain was riding on one side of the chain and when it fell off the sproket could the valve have hit the piston and got bent?

GM, didn't see your last post about the bent valve until after I asked about it.

[Mech]

You do have a bent valve.

[DaveswMN]

GM, didn't see your last post about the bent valve until after I asked about it.

The original cylinder gasket had the open spaces on three of the holes and included an o-ring. There is no seat for the o-ring on the cylinder I bought and the gasket I bought does not have the open spaces on the gasket. Is this ok?

[Gwbarm]

I think it will be OK , but if you can send me a link to what you bought i will take a closer look.

[Mech]

I'll butt out then.

If you get stuck and want more advice mention my name and I'll be bound to see it.

[Gwbarm]

Mech! Your opinion may be more valuable than mine here, I have not seen a 225 only 250s and 350s. The rebuild kits comes both ways as he described.