Can anyone explain this?

[monk34]

i just discovered this when opening up a p-41 pioneer chainsaw. It would start and run for a bit before stoping. What could have caused this?

 

[rupedoggy]

Somebody trying out his aluminum welding skills while also increasing his compression?

 

[monk34]

Somebody trying out his aluminum welding skills while also increasing his compression?

would you think the chainsaw would still work like this? The sides are not scored at all

 

[9050lx]

Are those craters or bubbles? Cool.

 

[djones]

I would think somebody sucked up a mouth full of bb's but it's probably a ball bearing that fell in through the carb.

 

[monk34]

Are those craters or bubbles? Cool.

craters lol

 

[monk34]

I would think somebody sucked up a mouth full of bb's but it's probably a ball bearing that fell in through the carb.

i think so because all the craters are pretty much a perfect circle. Do you think the chainsaw would still work like this?

 

[Canyon Angler]

Not easy to "squish" hardened bearing balls!

 

[EchoRomeoCharlie]

Ball bearing got in there...potentially from the crank bearings?

Bet that didn't sound good...lol

 

[9050lx]

Could it possibly be a butterfly screw?

 

[Bob Hedgecutter]

Well, that is one way of de-carboning a combustion chamber I guess.

 

[PV Hiker]

What does the under side of the piston look like? Any cracking?

 

[TLG]

Dang, That's one for a failure analysis book. I can't believe the spark plug survived and it still ran or the cylinder bolts didn't stretch and fail.

 

[monk34]

What does the under side of the piston look like? Any cracking?

none whatsoever. Only damage is to the top of the piston and cylinder.

 

[monk34]

Could it possibly be a butterfly screw?

possibly, the only thing is I found nothing in the combustion chamber which I managed to unseized with heat. Would you think i could weld in the holes and sand it down?

 

[ChillyB]

I think any repair attempt would add risk. I’d blend down sharp edges on piston with a Dremel polishing something-or-other. They make a rubbery wheel with embedded abrasive. The outer edges of crown may be peened outward so maybe flat file the edges back to cylindrical. Ring groove may be crimped below peening too. A jewelers file may address any of that.

Then I’d assemble and run. No way I’d weld it.

 

[monk34]

I think any repair attempt would add risk. I’d blend down sharp edges on piston with a Dremel polishing something-or-other. They make a rubbery wheel with embedded abrasive. The outer edges of crown may be peened outward so maybe flat file the edges back to cylindrical. Ring groove may be crimped below peening too. A jewelers file may address any of that.

Then I’d assemble and run. No way I’d weld it.

ok thanks

 

[dave ensign]

Take off the muffler, shake it, does it rattle?

 

[ChillyB]

ok thanks

I'm not very bright sometimes so if you care about this saw Id fix it right. Cold-hammering aluminum with a ball bearing probably put invisible cracks in it.

 

[monk34]

I'm not very bright sometimes so if you care about this saw Id fix it right. Cold-hammering aluminum with a ball bearing probably put invisible cracks in it.

You mean repace the piston?