346xp OE 42mm bore question

[GusGus2020]

Edit - the title is supposed to be ‘OE’ instead of ‘or’.

I just got a 346xp relatively cheap - some parts need to be replaced but it’s a solid runner other than that. My question is whether anyone has seen a 2 ring piston in these before? Best I can tell, without having pulled the cylinder yet (need to do some more cleaning first), it has a 2 ring piston with only one ring in it. Definitely been run that way for a while, and the cylinder/piston are in what appears to be great shape. Looking around, a 024 Stihl is the same bore diameter - do people use these occasionally?

 

[GusGus2020]

No one ever see this before? Been working on cleaning it off - should I pull the cylinder and replace the piston, or run it until it does?
Guess I’ll be pulling the cylinder anyway to change out the plastic intake clamp, so we’ll see what it looks like.

 

[Chevboy0167]

OEM stock sure looks to be 1 ring by my quick search. But there are some aftermarket big bore kits with 2 ring setups. I would guess someone stuck something in there that ain't stock.

Your call on to run it or check it out further. Me... I would be leery of toasting a good stock cylinder if it hasn't already. I would tear it down and check cylinder bore and condition. If ok, replace with Meteor piston kit with Caber rings.

Just a note..... Meteor is showing 3 different sizes.

41.95mm
41.955mm
41.96mm

 

[GusGus2020]

Thanks for the input. It certainly looks like a stock 42mm cylinder, non removable transfer port covers. Ill check everything over once I finish cleaning and pull the top end off. Need to clean out at least the exhaust port, too - a lot of carbon buildup that I would rather. It have break loose.

 

[r black]

i only see one ring ?, however the cylinder if oem will be stamped with...... mahle on the side ... it appears stock from the top pick , if not .....a new oem piston and cylinder is only around $100 and worth the investment

 

[GusGus2020]

i only see one ring ?, however the cylinder if oem will be stamped with...... mahle on the side ... it appears stock from the top pick , if not .....a new oem piston and cylinder is only around $100 and worth the investment

I couldn’t get a good picture of both rings originally - here’s a new one of the rings, and one of the transfer port area - I don’t see Mahle, but it might be lower or on the other side?

 

[redunshee]

You may as well pull the cylinder to be sure.

 

[huskihl]

It’s an oem 42mm cylinder. You can just make out the 42ZN casting numbers with the +++ symbols above it. I’d still pull it and use a meteor piston. Or if the cylinder is worn I’d replace it with new oem

 

[GusGus2020]

Now I’m even more confused...pulled the cylinder and what did I find? A Mahle dual ring piston...
Are there any dealers/repair techs that have seen these before? And if so, what do you advise in this case?

 

[Chevboy0167]

I do see a note about a new, (after December 2007), model but looks like still 1 ring. Also the bore is bigger...44.3mm.

 

[cuinrearview]

Last fall an ebay seller listed this part number with not much information. I searched the number and found it on Bailey's. With this info I purchased it. It is the piston you have. 42mm, visually identical to a 346 piston, with two 1.2mm rings instead of one 1.5mm. I plan to run it with just the top ring on my next OE build.

https://www.baileysonline.com/husqv...2mm-345-346xp-544093002-hvp-544-09-30-02.html

 

[RedneckChainsawRepair]

Think I still have a aftermarket 2 ring piston for these here that came in a box of stuff. Always wondered why.
Guess there is my answer, even oem had one. Never had a 346 saw with one in it though.

 

[GusGus2020]

Last fall an ebay seller listed this part number with not much information. I searched the number and found it on Bailey's. With this info I purchased it. It is the piston you have. 42mm, visually identical to a 346 piston, with two 1.2mm rings instead of one 1.5mm. I plan to run it with just the top ring on my next OE build.

https://www.baileysonline.com/husqv...2mm-345-346xp-544093002-hvp-544-09-30-02.html

Good to know, and nice that it seems like we have an answer. I’ll be ordering another ring for it, since I have the top off. Need to take off a bunch of the carbon buildup from the exhaust port, too, but it’s great to know this should run fine, long-term!

 

[GusGus2020]

Anybody have the difference in mass between an actual OE piston and ring vs this setup? I’ll get one for the 2 ring later today.

 

[GusGus2020]

Progress is being made - cleaned up the cylinder (decarbonized, slightly widened the exhaust port), base gasket delete (squish is still a bit high @ .023, but I don’t have a lathe...), helicoiled the muffler bolt holes, muffler mod using stock outlet, went through the carb, metal clamp and new impulse tube - somehow there wasn’t an air leak in that area. Both the clamp and impulse tube were loose and cracked.

All back together except for the chainbrake and need to get a muffler support bracket. I thought I could salvage the chainbrake from a 350 that I had, but no such luck...