Once upon a time I had a knock-off, unreliable chainsaw. I ran it lean and locked up the engine, so I tore it apart and replaced the piston, rings, and cylinder (did a top-end rebuild). The new piston promptly broke, and a little piece of it dropped into the crank case and did unspeakable things to my bearings.
So I tore it apart and replaced the bearings, seals, and crank (did a bottom-end rebuild). The broken piston was missing a little chunk of metal way down on one corner of the piston skirt, but the critical surfaces were all in reasonably good shape, so I smoothed out any rough edges and re-used it.
Well, that saw had been misbehaving ever since (and ever before, if I'm being completely honest). I'd screwed with the carburetor a ton and gotten it to the point where I could run it, but it was never quite right. I developed a hypothesis that maybe that missing patch of piston skirt was screwing up the porting geometry and timing.
So I started watching the cheap-o rebuild kits of eBay for one to get cheap. It eventually did, I ordered it, and it arrived. The only logical thing to do next was to install it.
So that's how I found myself rebuilding the top end on this piece-of-junk saw yet again. Luckily at this point I was getting pretty good at it, so it was a quick afternoon project. Everything went smoothly, and the new parts seem to be performing much better, so I think this project was actually a pretty good win.
4 янв 2024
