090 project

[cease232]

I was recently on vacation with the family and found this 090 on the local craigslist. Decided to check it out. According to the older fella who owned it for the last 40 or so years he'd never cut wood with it. His uncle owned it originally and gave it to him when he quit logging. He used it as decor and would start it every few years. Didn't have my gauge but compression felt ok. Piston looked good after removing the muffler. Everything was OEM and intact aside from the recoil cover being broken and the muffler exhaust outlet cover missing.

Well I bought it for 499$ and couldn't wait to get home and take it apart. Upon disassembly I discovered a small clip that holds the choke lever missing and the plastic elbow on the bottom of the carb broken. I wanted to keep it all OEM but seems it may not be possible. Found the OEM exhaust cover but not the locking strips that hold it on. Was going to order an aftermarket carb for just the plastic elbow and I thought I could make the plastic clip from some UHMW plastic I have in the shop. It appears to me that this saw has never been taken apart.
Now for the technical part. The Piston was scored on the intake side and the cylinder has minimal transfer but what appears to be a small chip in the plating. I'd like to not replace the cylinder if possible.
Measurements:
Squish .043
Gasket .021
The bottom ring overlaps the chip at BDC by
Approx .02
If I deleted the base basket the bottom of the ring would just barely miss the top of the chip.

I haven't been able to find an OEM piston so was considering using a Hyway brand. These numbers are irrelevant if the aftermarket piston doesn't mic out exactly the same. I'll probably order one just to find out. The other option is a new OEM piston/ cylinder on eBay for $400. Hoping to avoid that if possible. Thoughts, comments, recommendations appreciated. I'll update this as I make progress.


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[jacob j.]

The Hyway 090 pistons are a crap shoot. I've gotten one that looked really good and fit the bore of an OEM cylinder great, and one that was terrible and was such a tight fit in an OEM jug that I couldn't even move it to the top of the cylinder by hand. The gouge in your plating is down low so I would say blend that in by hand and you'd be good to go.

 

[cease232]

Thanks. I don't know what other option I have. Meteor doesn't make a piston for the 090 and Can't find and OEM. Hyway is the only brand I've heard halfway decent remarks on.


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[jacob j.]

I would go ahead and try one. You can get them cheap enough that you're not out much money. I would go for Caber rings though and I would re-use your stock OEM wrist pin and clips if they fit the new piston well.

 

[cease232]

That was the plan. The piston, and caber rings would run me about 60$ with shipping. Worth a gamble.


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[sawfun]

The Baileys 090 piston and cylinder I had on an 090 worked great and made the same power as oem but I doubt if the plating would last as long under everyday real logging conditions

 

[drf256]

Why are you changing that piston?

I now put new OEM/meteor pistons in all of my builds (preferably OEM).

In this case with your rare setup, I'd sand that carbon rashed area and add new rings. The skirt looks pretty good.

Get a diamond ball and blend that chip in the plating lightly.

You could even just add a top ring, leave the old bottom ring (or use the current I damaged top ring on the bottom-worn in and less tension than new) and reduce squish to .020 sans gasket. With the geometry you are discussing, why not.

The exhaust cover may be able to be welded.

 

[shawn022]

I just bought an OEM 090 66mm piston from a dealer. I think it was $75. Took 8 weeks to get though. It just showed up yesterday.

 

[cease232]

Why are you changing that piston?

I now put new OEM/meteor pistons in all of my builds (preferably OEM).

In this case with your rare setup, I'd sand that carbon rashed area and add new rings. The skirt looks pretty good.

Get a diamond ball and blend that chip in the plating lightly.

You could even just add a top ring, leave the old bottom ring (or use the current I damaged top ring on the bottom-worn in and less tension than new) and reduce squish to .020 sans gasket. With the geometry you are discussing, why not.

The exhaust cover may be able to be welded.

The thought crossed my mind but I've never reused a scored piston before. You can't tell in the picture but up close it looks "chunky". Like a piece could flake off. That was my fear at least.


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[cease232]

I just bought an OEM 090 66mm piston from a dealer. I think it was $75. Took 8 weeks to get though. It just showed up yesterday.

Was that from your local Stihl shop? I asked my local guy but he just throws out answers without checking anything.

 

[big t double]

list on an oem piston is about 65...your mileage may vary.

 

[huskihl]

I'm with doc. File the high spots off and run it. And fix the air leak

 

[cease232]

Went to the dealer today. Like I suspected he told me it wasn't available. Asked him to look it up anyways. There is was $65. Had him order me one. Hopefully it doesn't take 8 weeks to get here now. I'm gonna replace all the gaskets and seals while I wait.


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[smokey7]

I don't get why saw pistons are so much mo ey. I can buy oem bike and ski pistons much larger for around the same and they come complete with rings pin bearing and clips.

 

[TJ the Chainsaw Mechanic]

Stihl's gotta make a bunch of money somehow. lol They take a little to much pride in their stuff imop.
In for this build!

 

[cgraham1]

Went to the dealer today. Like I suspected he told me it wasn't available. Asked him to look it up anyways. There is was $65. Had him order me one. Hopefully it doesn't take 8 weeks to get here now. I'm gonna replace all the gaskets and seals while I wait.

Well???