yeah that engine i fixed up was a bastard child this weekend. it starts up wonderfully and for quite some time it runs wonderfully as well. thing is when i reinstalled the engine i was having grounding problems so i got some wire that was lying around and made some ghetto grounds. worked for a while until they burnt out, turns out they were too small for the current. made some bigger ones and worked rather well....until the bloody thing overheated

so it overheated to the point where it couldn't run. i didn't know that this was evening happening when i was working on it. i was fixing it up for my mom who's 2 hours drive away and she neglected to tell me that it was overheating...figures.

so any ideas? where do i start? when i had it apart it was cleaned out throughly, valve seats reground, valves shortened slightly (they were stretched) but other than that everything looked in remarkable shape. she cylinder bore looked very very clean, valve guides seemed to run smoothly with the valves no noticeable play. no noticeable play in the piston either. i didn't open the bottom end because i just didnt think i needed to.

there is definitely nothing blocking the cooling fan and it runs smoothly. so whats left?? only thing i can think of is maybe the carb is running ridiculously lean? it is quite a bit quieter than it used to be but that could mean anything...i figure maybe it just needs a tad more fuel in the mixture to assist with internal cooling (fuel evaporates, removes a bit of heat)

so anyone? i'm really stumped here and i have to get this thing going

Is the fins on the motor clear of depris and have all the shouds on it ? is the Screen ontop of the flywheel cooling fins clear? Is their addiquit air flow to the engine? . Normally if the carb is to lean it wont even run.

yep the whole thing is clear there is no way anything can be blocking it. as i had said before i had this thing apart completely with the exception of the bottom end and the carb i didnt go into either - didnt think there was a need.

First question, how are you determining that it is over heating, sometimes just the leftover oil and cleaner from a rebuild will create a lot of smoke and stuff. Have a good one. Geo

by overheating the thing will run quite well for a while then begin to struggle until it stalls. open the hood and theres a little bit of smoke rising from all around the engine. at this point its near impossible to turn the engine and if you leave it for a while it runs again just fine.

Do you have the right amount and grade oil in the engine ? It takes a 30 weight high detergent oil and should be 48 oz. But usually the first sign of the engine not having enough oil is the piston rod blowing through the engine behind the starter. The only other time iv seen an engine over heat is when it the cooling fins where blocked off with debris .

Just doned on me Are your timing marks between the crank and cam correct ? You said the engine was quiter then usual. Or the clearance between the valve lifters and the valves are off spec.

yes there is enough oil in it and it is the right oil. no the timing cannot be off as i did not open the bottom end of the engine, only removed the head and did some valve work - it is a pushrod engine.

You mean OHV ?

no i mean pushrod just like i said. it is not an overhead valve model

Please post the engine numbers usually found on the engine shroud just above the spark plug so we can see what you have. I have never seen pushrods on anything other than OHV engines. Have a good one. Geo

model is 281707, its an older one where the cams are geared right to the crank and the valves are actually in the block next to the cylinder

We are getting the timings confused, the crankshaft/cam marks are valve timing, the flywheel/magneto is ignition timing. You could have a sheared or partially sheared flywheel key pt# 222698 which could be creating the problem. Have a good one. Geo

model is 281707, its an older one where the cams are geared right to the crank and the valves are actually in the block next to the cylinder

This is an "L" head engine not an OHV, what you must be calling the "push rods" are actually the valve tappets and some call them lifters. This engine does not have any push rods.

If it's quieter then usual and you suspect that it's overheating, I would look for a restriction in the exhaust, perhaps a loose baffle or plugged spark arrestor screen (if so equipped...and yes some 4 strokes have spark arrestors). Also as geo suggested a partially sheared flywheel key could be the culprit as well.

Good Luck...

ah yes my bad on the pushrod/tappet thing, mixed up the names. so a partially sheared flywheel key...i know the key on the bottom pulley is ok, but i'm assuming you're referring to a key on the top air cooling fan (assuming thats the flywheel) if thats so, then wouldn't it be possible to just spin it by hand and feel some play on the shaft?

Yes thats the flywheel. No even if the key is partially sheared you would not be able to spin it by hand. If the ignition timing is off a little it could cause the engine to run hot, but if it's very far off... chances are the engine would never start.