041AV rebuild/porting question/build

[Nutball]

Like holding the piston in the cylinder and finishing it through the intake port? Great idea

 

[DucTruckin379]

you can always just grind notch to match port wall, that will keep piston stability in bore.

Like holding the piston in the cylinder and finishing it through the intake port? Great idea

That's the plan. Just scribe where to remove with the sides, and then the floor of the port. It'll leave about 1/4" on the sides to support the piston. Picture is just for description (removing sharpie), layout will be much more precise , with scribe lines. It looks really rounded in the picture (half my drawing skills, half the curve of the piston), but won't be when it's cut. I'll do it out of the bore though, as the top of the cut needs to match the bottom of the intake floor.

 

[DucTruckin379]

Well, it's been a whole minute, with family and work etc., but it's back together and runs awesome. Turned out exactly like I was hoping (thanks to y'all's help). With a 20" (what I had sitting there), and a fresh square filed chain there was no bogging it no matter how hard I dogged it in (poplar is what I had laying that I could bury the bar in). It was getting dark, and without much time and on new rings I left it a little rich, but it's definitely gonna be mean when it's broken in and tuned up. Actually, it already is...

Numbers ended up at:
Exh: 103
Trans: 120 (didn't modify)
Int: 76

I decided to go a little more aggressive than the original plan, but left the intake a little conservative so that I could take some off the jug later if I decided to tighten the squish the last .010 or so.

The exhaust turned out decent I think. Not much room for overall size increase with the muffler on this saw the way it is, but I was able to get the height I wanted, and was able to widen it just past the original bevels. I know it's probably a little over the top going this far with the polish, but I had the stuff sitting there, and it took an extra 2 minutes.




This is the kinda cruddy left hand tracing to get an idea of the shape (it's not actually that lopsided on the bottom, and the intake is untouched). I probably could have gone a little flatter but I think better safe than sorry in this case...




Here's the piston. This is while I was checking timing, before I cleaned up the edges of the little "legs" on the bottom.



The honed cylinder:



And the results:



I've still got to find an inside dog for it. It didn't have one when I got it years ago, and I've got a washer on the way to finish the rim sprocket conversion. I threw the old spur back on because I couldn't wait to fire it up...
Besides that, I've got one screw hole to re-tap (and find a screw) on the exhaust cover and I think it'll be done!
I decided not to re-paint it because I liked the patina and I wanted it to look like I remember when I was 18...

I appreciate y'all's recommendations and discussion. I'm happy with it!

 

[DucTruckin379]

Ok, more legit test this evening. 28" 33rs straight off the roll. Buried in the same poplar, pulled it good. It's definitely not as snappy as the new saws, but it does have a bunch of torque. My ms362 had all it wanted with a 24" when I was bucking this stuff, but I didn't have time to get it out for a back to back. Maybe tomorrow...

And I knew the holey jeans were a bad plan...

 

[Wonkydonkey]

Ok, more legit test this evening. 28" 33rs straight off the roll. Buried in the same poplar, pulled it good. It's definitely not as snappy as the new saws, but it does have a bunch of torque. My ms362 had all it wanted with a 24" when I was bucking this stuff, but I didn't have time to get it out for a back to back. Maybe tomorrow...

And I knew the holey jeans were a bad plan...

View attachment 348520

this pic should be added here
https://opeforum.com/threads/lets-see-them-chips.27028/page-8