346XP needs replaced....it's at 90 PSI, what saw is comparable today?

[zeek]

Old & worn out is pretty improbable given that you have replaced the ring.
There are good pictures of damaged pistons for your reference here: http://www.madsens1.com/saw_piston_fail.htm
I would expect it would have stood out when you had it apart if it was.
Did you leak test it once you put it back together?
If your piston & cylinder aren't scored in any way I would suspect whatever is causing your low compression will be fairly cheap & easy to fix once you identify it

I don't have the tools to leak test so that is not good. But any ideas on what is causing the low compression? Gotta be top end?

 

[TRTermite]

You also need to check the end gap of the ring in the cylinder Use the piston to square it up and feeler gauges to measure. This needs to be done in a clean (no transfer) cylinder.

Cylinders don't usually wear as the nikasil is VERY hard. I suspect that you have been running a previously seized engine. Post some photos of the inside of the cylinder. You also need to get that muffler off. Penetrating oil and heat.

Some times a flat Punch (and Hammer) placed on the muffler bolt head and a few solid smacks will help break the bound threads. Check the allen head of muffler bolt is clean and use the right sized allen wrench from a 1/4" impact driver kit to use as a punch. Heat and penetrating oil and heat for sure. I have an old roaster pan collecting dust that I grab when needed to heat something like a case or cylinder.

 

[Chevboy0167]

Your first pic isn’t just the old edition. The ne 346 has the same cylinder with 44.3mm bore vs oe being 42m. Both are xp

Your 2nd pic is the homeowner/semipro non xp version used on the 350, 351, and 353

Thanks huskihl, I didn't know that. I thought it was pretty much cut and dry hence NE = new design.

Would the surface area of the transfers be the same? And I believe the bolted on cover is for clearance issues yes?

 

[flatsfisher]

from the questions you ask, I don't think you should be pulling this saw apart to fix it unless you are mechanically inclined. if you aren't, maybe sell it to someone who can fix it and get another.

 

[huskihl]

Thanks huskihl, I didn't know that. I thought it was pretty much cut and dry hence NE = new design.

Would the surface area of the transfers be the same? And I believe the bolted on cover is for clearance issues yes?

The outside dimensions of the XP cylinders might be the same. But the bore size and the ports are different inside.

The change to the bigger bore cylinder on 50cc saws from Stihl and Husqvarna was from EPA restrictions being put in place on sub-50cc saws. Both the 346 and the MS260 we’re only 45-ish cc Increasing the bore on each of them put them over the 50cc mark so they didn’t have to comply with those emissions restrictions.

The cylinders with caps are easier/cheaper to produce than the xp version bottom fed cylinders. The swooping transfer tunnels are better for performance, as opposed to the more vertical open/semi-closed ports on the non xp models. The 346, 351 and 353 are all built on the same case but used different cylinders. 350 was the plastic version that ran the same cylinder as the 351/3. It needs a little clearance work on the clutch side to fit the xp cylinder but not much. I don’t think the reason for the caps is because it could be made narrower. It was just a byproduct

 

[Mad Professor]

When you ringed it you should have checked P/C clearance with feeler gauges.

Was there any scoring/aluminum transfer on cylinder?

 

[Brushwacker]

There isn't an Echo in that class that can hang with a 346xp.

I was disappointed with the Echo 490,s power myself.
If i were in the OP 's position ' going new the cs590 I think or a nother reputable 55 to 70 cc saw, would be at or near the top choice for various reasons. It would handle a 3/8 20in bar better then a 346 and save some back bending. Fix the 346 at your convenience to run a smaller b&c and or find you a small light beater saw for when it's neccesary to cut ground level or dirty wood and it would give him a break using it limbing also. The small saws can be bought cheap and save a lot of wear and tear on more expensive equipment and parts. When your top saws are sharp and well maintained they buzz up the large stuff much easier and faster. If u can have a small saw also , it makes sense not to dull and wear out a bigger saw on small wood.

 

[Lionsfan]

from the questions you ask, I don't think you should be pulling this saw apart to fix it unless you are mechanically inclined. if you aren't, maybe sell it to someone who can fix it and get another.

Why not? It's just a saw.

 

[flatsfisher]

Why not? It's just a saw.

this is true. maybe use it for practice.

 

[bwalker]

I was disappointed with the Echo 490,s power myself.
If i were in the OP 's position ' going new the cs590 I think or a nother reputable 55 to 70 cc saw, would be at or near the top choice for various reasons. It would handle a 3/8 20in bar better then a 346 and save some back bending. Fix the 346 at your convenience to run a smaller b&c and or find you a small light beater saw for when it's neccesary to cut ground level or dirty wood and it would give him a break using it limbing also. The small saws can be bought cheap and save a lot of wear and tear on more expensive equipment and parts. When your top saws are sharp and well maintained they buzz up the large stuff much easier and faster. If u can have a small saw also , it makes sense not to dull and wear out a bigger saw on small wood.

If you want a lightweight saw I can't see buying a 60cc echo.
The idea of using a small saw to save wear on a big saw is frankly ridiculous. Most guys on this site have never and will never wear out a saw.
I also would not be so sure that a 60cc echo will out cut a 346.

 

[zeek]

from the questions you ask, I don't think you should be pulling this saw apart to fix it unless you are mechanically inclined. if you aren't, maybe sell it to someone who can fix it and get another.

I am mechanically inclined, but the questions I am asking are pretty specific to chainsaws/2 strokes and asking them has nothing to do with my mechanical ability. Being inexperienced and not as knowledgeable as you all is why I came here for help. Remember, we all started off not knowing "righty tighty..." or how to use a screwdriver, hammer or do a squish test. We start from the same point, ignorant, but that doesn't mean we have stay that way. I have torn it apart, again, and thanks to the posts here I found the problem, learned a lot and hope to encourage the next guy asking "questions" to go for it. Will post pics in ASAP.

 

[flatsfisher]

I am mechanically inclined, but the questions I am asking are pretty specific to chainsaws/2 strokes and asking them has nothing to do with my mechanical ability. Being inexperienced and not as knowledgeable as you all is why I came here for help. Remember, we all started off not knowing "righty tighty..." or how to use a screwdriver, hammer or do a squish test. We start from the same point, ignorant, but that doesn't mean we have stay that way. I have torn it apart, again, and thanks to the posts here I found the problem, learned a lot and hope to encourage the next guy asking "questions" to go for it. Will post pics in ASAP.

that's why I stated, "unless you are mechanically inclined". please accept my apology. chainsaws are actually fairly new to me also, but I've been re-building 2 stroke dirt bikes for almost 50 years.

 

[zeek]

Thanks to all of you, and @J D that link about piston failure was great. I did not know what I was looking for, and now that I see what I missed....well it's bad. But I do know that scratches are bad and I am not sure if the first time I had it apart for the ring the damage pictured was there. My son claims that we both would have seen such obvious problems and he is pretty good with engines and has rebuilt a few ATV's and such. He claims that the damage was caused after we put the ring in and made 2 cuts with it to test it. Could that kind of damage happen on a 3-4 minute time frame?

I am going to replace the P/C with OEM. Now to figure out why this happened, but it's been losing power for a while and I just didn't think enough about it, just sort of thought well it's getting old. See pics and feel free to offer your insight.

 

[J D]

I suspect that cylinder is quite salvageable.
Piston maybe less so.
Looks like you had the ring rotated the wrong way, that would be half the reason for the low compression (along with the transfer on the cylinder)

 

[Bob Hedgecutter]

The ring is installed upside down and not in relation with the ring location pin- that certainly did not help.

 

[sean donato]

Yep these guys nailed it with the ring.

 

[J D]

Now to figure out why this happened

Vac/pressure test is now a must as a leak is a likely cause of that failure. Hard to tell from those pics but it looks like you have the metal intake clamp already. If that is the case that's one less thing to worry about.
Check inlet boot & impulse line thoroughly for any splits or holes, inspect seals, clean transfer off cylinder & replace piston.
Put everything back together with a 2 stroke fuel rated sealant (not rtv) & DO A LEAK TEST

 

[Bob Hedgecutter]

Hard to tell from the photographs, but the cylinder might not be in tip top shape any more- just judging by the amount of wear in the ring about exactly where the exhaust port might be- has it shaved the cylinder lining above the exhaust port? Some of the light grey spots almost look like through the plating , not just transfer- but hard to tell as I say.
In the first photo of the piston it almost looks like the top of the piston is pitted?

 

[J D]

Need some more pictures for sure

 

[sean donato]

For $150.00 I'd just toss a new top end on it. Do the crank seals while your at it. Check over the intake boot and replace the fuel lines. Call it a day for under $200.00.