The scored piston you're running

[irhunter]

I understand the convention is to replace scored pistons...after dealing with the underlying issue.

But, I also read where some guys dress scored pistons add new rings...and, run them.

So, if you're running a scored piston, please report how it's going. Pic of piston would be nice, too.

Thanks,

Roy

 

[RedneckChainsawRepair]

I put a really bad 353 scored piston back in a saw to be a tester. I cleaned it up fixed ring groove, put new ring on it. It came back in 2 years later still running and cutting and still looked bad but worked. Firewood user that ran them hard and put up wet too.

I couldnt tell any difference cutting with it stock for stock.

 

[ChillyB]

I'm thinking to do it. Also thinking to use a ring that breaks in easily since my bore doesn't have the cross-hatch it once had, and I don't have a hone. I do think I can somewhat refresh the cross hatch by hand.

 

[irhunter]

my bore doesn't have the cross-hatch it once had, and I don't have a hone. I do think I can somewhat refresh the cross hatch by hand.

I've only been inside a dozen, or saws, but I don't believe cross-hatch is a "thing," in the case of chainsaws.

The super-hard plated chainsaw bores are not like automotive iron or steel (liners) bores.

Roy

 

[oldguy]

I have done 3 of em now, all of these were only scored at the exhaust port.
A 346, a 353 and a 365 spcl. I made sure the transfer was gone from the cyl. and made sure the new ring moved freely.
I used the 346 & 353 for two summers, I( put a 20'' bar on the 346 & used it hard, both saws are still grinnin. I asked the guy with the 365 how it was doing, he said it was fine

 

[ChillyB]

Figured cross hatch would be important for ring seating regardless of engine type. Buy I'm fairly new to 2-stroke work.

 

[irhunter]

Figured cross hatch would be important for ring seating regardless of engine type. Buy I'm fairly new to 2-stroke work.

I can see thinking that. Since it is so important in automotive motors.

I have never seen any signs of cross-hatch in a chainsaw bore. Even in a crazy-new MS291, which I happen to have apart now.

Rather the cross-hatch in chainsaws, it seems the goal is shiny and aluminum-transfer free. Thus:




Roy

 

[singinwoodwackr]

I just picked up a near new 395. It has very clear cross hatch in the cyl.

 

[RedneckChainsawRepair]

My cylinder was cleaned up and fresh crosshatching put in. I call it as easy as 1 2 3

This 670 got the same.

 

[RedneckChainsawRepair]

This 346 NE was a harder one to save. But manged to make usable.

Just sold it to a collector user too.

 

[irhunter]

Well, there you go.

Seems you can skin the cat with or without cross-hatch.

Maybe the next post will be from someone who uses a stone-base hone!

Roy

 

[ChillyB]

I have a riddle on my hands. Saw was filthy, Mahle jug evenly pasted with a thick patina of baked on crud, gave no indications of having top end work in recent memory. Purchased as a project saw that would start but not stay running. I never tried to start it.

The cleanest part of this saw is the piston. Appears near unused except scuffing that I suspect is from carbon. Still has machine marks on skirt. This saw was not well treated so suspect it must have actually been worked on.

can anyone ID source of this Husqvarna 365 Special piston? If it's high quality I'll reused despite some scuff which have been knocked back with emory paper. If not high quality I have some thinking to do.

 

[ChillyB]

Mystery piston has what appears to be a small caligrophy type font "S" stamped on the crown.

 

[singinwoodwackr]

Aftermarket piston, not Meteor or Hyway. And, what’s with the hole in the top?

 

[ChillyB]

Aftermarket piston, not Meteor or Hyway. And, what’s with the hole in the top?

It's a shallow divot, presumably to indicate which side is the front of the piston.

If it's not OEM,, meteor, or HyWay then it's a paperweight, I think. There is barely perceptible wiggle at the wrist pin.

 

[singinwoodwackr]

It's a shallow divot, presumably to indicate which side is the front of the piston.

If it's not OEM,, meteor, or HyWay then it's a paperweight, I think. There is barely perceptible wiggle at the wrist pin.

Pin should be snug.

 

[RedneckChainsawRepair]

Well, there you go.

Seems you can skin the cat with or without cross-hatch.

Maybe the next post will be from someone who uses a stone-base hone!

Roy

Step 3 fresh crosshatching not needed. But one year I tried it on a fresh rebuild on a 166 race saw. I was like hmmmmm liked the results. So I started doing it on all of mine.

But no it is not needed. Plus many have no clue how to do it right. Slow both ways and not long couple seconds.

Do not try to use for transfer removal. Seen some try that.

Can just use a scotch brite pad at end if one wanted for step 3.

Some of these new saw cylinders today look like a mirror finish though. I wouldnt try it on those.

GL


Brand new NOS cylinder has crosshatching.

 

[stihltech]

Until you have to repair a saw that the new rings did not seat until crosshatched, you will not see the difference. Compression (against my better judgement) went from 80 psi to 125+ after 1 minute of run in. It is basic mechanics. A 2 stroke is still basic mechanics.
Was there enough roughness left in the cylinder to seat the rings without the glaze broken (NOT HONED!)? That is possible.
Rings gotta seat.

 

[JimR]

Figured cross hatch would be important for ring seating regardless of engine type. Buy I'm fairly new to 2-stroke work.

Saws have a hardened liner. Good luck trying to cross hatch it. I don't bother even trying. Make sure there is no piston transfer and let it rip.

 

[Gord404]

Pin should be snug.

just took down a 372 with well over 100 chords on it- meteor piston and cylinder are in great shape- will put a new rig on it but the caber I'm replacing still has some spring left in it- cylinder is perfect- took it down to replace a case half.- I do use a ball hone once in a while just a quick in and out2 times either way just to check any tranfer that might still be there and have a scotch brite muff I made up to get it relally nice- leave chome plating alone - but most of the time just scotch brite