Normal Ring Blow-by?

[redtractor]

Is this normal blow-by for 9 years of doing about 10 to 15 cords a year?

I pulled the jug off my 346xp(oe) for a base gasket delete. The piston still has the machining marks and the cyl is still cross-hatched so all I'm changing is the ring. For the first 3 or 4 years, I didn't know how to tune my own stuff and used crappy oil. Now its tuned sweet with FD rated stuff.

 

[Termitebuffet]

What is the ring gap on the old ring ... Looks reasonable to me from what you described...

 

[Chainsaw Jim]

That's what poor quality oil can do. A brass wire brush and some good cleaner will have it looking good as new.

 

[jmssaws]

Looks normal to me.

 

[stihl saws]

Looks great to me. Clean it up, new ring and run it.

 

[redtractor]

What is the ring gap on the old ring ... Looks reasonable to me from what you described...

Gapped at .014 and had a breath under 180 psi. Is the healthy compression part of what makes it look like this? Muscling its way past?

If you would've asked me a few years ago to tear down such a strong saw, I'd have given you the strangest look!

 

[huskihl]

.014 is still serviceable, but a new caber is only a few bucks. .006 to .008 or so is what the new ring should be. I think husky says .040 is the limit

 

[smokey7]

Looks normal as far as it being a 2 stroke. I'd be interested in the crown and underside of piston pictures too. It blew 180 before deleted gasket?

 

[redtractor]

Looks normal as far as it being a 2 stroke. I'd be interested in the crown and underside of piston pictures too. It blew 180 before deleted gasket?

Totally forgot about checking out the bottom. Pics tomorrow.

Yes, 180. I figured that was plenty as far as reasonable mechanical limits go but then found out what the ported ones are doing. I blame all of you. Bad influences, every one of you.

 

[redtractor]

.014 is still serviceable, but a new caber is only a few bucks. .006 to .008 or so is what the new ring should be. I think husky says .040 is the limit

I work at a Jred dealer, so was going to flex my discount & get OEM delivered to my work bench. Literally.

 

[stihl saws]

Gapped at .014 and had a breath under 180 psi. Is the healthy compression part of what makes it look like this? Muscling its way past?

If you would've asked me a few years ago to tear down such a strong saw, I'd have given you the strangest look!

Now the "in" thing is to switch oil daily and tear it down two times a day. Pics or it doesn't count.

 

[P.M.P.]

Seafoam and a toothbrush works real good. I would just flip it over let it soak for a little then hit it with the brush good as new.

 

[TJ the Chainsaw Mechanic]

One ring piston. Ya need two!

 

[Chainsaw Jim]

There's no reason to change the ring with compression like that.

 

[Marshy]

The area above the ring is nice and clean which tells me that the area under the ring is like that from past sins. Clean it up with your favorite smelling volatile cleaner and reinstall.

 

[redtractor]

There's no reason to change the ring with compression like that.

The area above the ring is nice and clean which tells me that the area under the ring is like that from past sins. Clean it up with your favorite smelling volatile cleaner and reinstall.

Even with the gap at .014? And I already have it in my hand since I had it opened up. It'd be a sin not to swap in a new one.

 

[redtractor]

I'd be interested in the crown and underside of piston pictures too.

In both pics, exhaust is on top.

 

[Marshy]

Even with the gap at .014? And I already have it in my hand since I had it opened up. It'd be a sin not to swap in a new one.

I agree since you have it in hand, forgot the end gap measurement but just like adjusting valves, you probably cant tell by performance if the valve lash is at the high or the low end of the range... My luck is I usually fix it until its broken but if you have one in hand put it in, its no more work at this point. Most never look that good, need replacing and still blow good numbers.

 

[Chainsaw Jim]

Even with the gap at .014? And I already have it in my hand since I had it opened up. It'd be a sin not to swap in a new one.

Generally speaking yes...generally the ring needs replaced due to low compression.
The next oem ring you use is probably going to have the same gap. Whoever broke it in did it as good as you want to do it. You risk never pulling that high of compression again when you change it.
Keep in mind your saw is still almost new considering the hours they're built for and the amount of time you put on it doesn't total more than about two months worth of professional cutting.

 

[bwalker]

Not normal. I HAVE posted pics of my very high hour 346 on the other site and the piston skirts are clean as can be.
It appears to me it got hot at some point based on the carbon under the dome.
The blown could be caused by cheapnoil, but more than likely poor ring seat when new or excessive ring wear.