I found a 225 the other day that the guy couldn't get running, I felt sorry for it and hauled it home, I have compression, have spark, have fuel and all I can get it to do is blow fire out of the back of the carburetor and catch on fire, I was thinking it jumped a tooth on the cam chain, but it's timed right, I pulled the flywheel cover off and found a small piece of cast iron stuck the the side of the pickup coil, figured that was it, but it's still the same. I couldn't see where the piece of cast broke off from, it's machined on one side and is about 1/2" long and 1/8"x1/8" and looks like it was the end of a finger of some type, like a timing advance weight, but I don't see any timing advance mechanism at all in there.

The kid I got it from said a buddy of his was riding it and it just quit running, he thought it was probably over revved.

 

Have you checked the boot between the carb and engine good to be sure there are no cracks causing it to suck air?

 

The little piece sounds like a woodruff key. Should see the groove it fits in on the crank where the rotor is pressed on. Only way to really tell if it's the key though is to pull the rotor off.

I would pull the cam cover and check that all the timing marks line up at TDC first.
Also, I'm sure a valve adjustment wouldn't hurt.

 

The intake boot looks good, I can see the woodruff key in the slot, so this piece isn't it, and it's cast iron, I checked the timing marks and they all line up, also the intake valve was pretty tight, so I loosened it up to where I can wiggle the rocker side to side, it acts like it's firing on the intake stroke, but I can't see anywhere to adjust the ignition timing, only the valve timing. I'm assuming the little pointer cast into the top of the hole where the cam sprocket is is the timing mark? I'm thinking there is a scratch at the bottom of the hole, but everything is lined up with the pointer, otherwise, that would make it 180 off.

 

Should be another pointer for the flywheel on the flywheel cover. Make sure it's lined up with the marks on the flywheel on the compression stroke first, then check cam timing.

No way that I know of to adjust ignition timing. That's what that woodruff key is keeping in place. Were you able to tell if the Cam and valves are working properly?

Might have a siezed valve or bad cam lobe not allowing exhaust to open or intake to close? Build-up in head could keep the intake from closing all the way.

If someone messed with the cam or sprocket, then it's possible the timing is out 180.

 

I'm thinking your right and it's a valve issue, they look to be opening and closing from the top, but there may be something caught under the intake, it has enough compression to blow air out of the spark plug hole, but I'm not sure it's enough to run. I'm going to pull the head Friday and see what I can see.

I'll let you know what I find.

Thanks for the ideas.

 

Evidently the previous owner either got it real hot or ran it out of oil because the piston was pretty well melted down, about 1/2 of the back skirt was broke off and the what was left was scored up bad, the rings move on the exhaust side, but are welded in place on the intake side. She's a dead horse

 

Ouch, that's never good. But still doesn't explain why it was firing thru the carb. Did the head/valves look in the same shape?
What are the plans for it at this point?

It could probably be revived but unfortunatly you'll have to split the cases to clean and make sure the lower end isn't toast also.

I'm in need a few parts off of it, if your looking at selling?

 

The head looked great other than alot of carbon build up on the faces of the valves. The little piece of cast iron I found on the flywheel turned out to be the tip of the exhaust rocker arm. I'm going to part it out, I bought it to make some money on, and if I invest in a top end, I'll break even at best, so parts are for sale, my email is oldsman67330@yahoo.com, if you send me your zip code and what you are needing I can figure shipping for you.