346xp OE 42mm bore question

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GusGus2020

GusGus2020

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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?C7F7F81A-A006-4900-9728-72559F8BC9B9.jpeg0C2FE175-131A-477C-A1F9-C614B7F55A4D.jpeg
FC2A1E78-B5BD-4F10-8C96-C69CA17B82D1.jpegE152C625-AB62-4385-AF0F-D6EDD5108A88.jpeg
 
GusGus2020

GusGus2020

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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
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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

Screenshot_2021-05-08 A9RE00D tmp - MetorPistonGardeningForestry2020 pdf.png
 
GusGus2020

GusGus2020

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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.
 
GusGus2020

GusGus2020

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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?34312645-C90D-40AF-B242-EDDCC4A6713F.jpeg233A42E9-A26B-49F9-B47E-6E1F9805EE9B.jpeg
 
GusGus2020

GusGus2020

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Now I’m even more confused...pulled the cylinder and what did I find? A Mahle dual ring piston...F076DC71-2015-4A0A-A099-A0CF88CF02C9.jpeg9325E28C-4AFE-4793-A122-BCDF2E2248E2.jpeg738561BD-BF39-408D-B770-A8198F7820C3.jpeg
Are there any dealers/repair techs that have seen these before? And if so, what do you advise in this case?image.jpg
 
cuinrearview
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GusGus2020

GusGus2020

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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.

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

GusGus2020

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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...

909E5D3C-1E8F-47F3-AE8C-9FA138E93120.jpegD96B2F45-FBFD-4232-919B-6E7F8DDD2286.jpeg5D40C44D-78C6-423A-A5B7-1920ADC25CBA.jpegBD115607-B3E6-423C-B570-C8A5EB20AFA9.jpeg0F0F1622-7CAD-4652-82B7-AC74DF0A3BC8.jpeg
 

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