Stihl O34 av Super advice

[641workmaster]

My saw needs a new piston due to a bearing failure. The cylinder looks and feels clean besides a little vertical color lines below the lower intake port. Should I gamble, and just get the piston kit or should I get an aftermarket cylinder kit? The saw is used infrequently.

On the replacement cylinders, I can't afford a stihl. What about NTW or Meteor? And do they all have holes for decompression valves? Mine originally didn't have this. Do I have to buy a plug or a valve?

Besides a gasket kit, any other replacement parts to be recommended? places to get this stuff?

FYI: I reposted this because a previous post has a bad link?

 

[Mad Professor]

Find out why it fried first.

Best non-OEM P/C kits are Tecomec, about $170

Get a OEM gasket/seal kit ~ $15

Bearing failure? sounds like you need to shop for a used OEM crankshaft and put new bearings on the lower end.

You will have about a new saw when done if you replace hoses and manifold..........

 

[Evan]

A lot of times the cylinder looks like its junk with piston aluminum smeared across the exhaust. A lot of times 2 or 4 hours scrubn with muratic acid all make them like new. I've coaxed quite a few straight gassed saws from the dead this way

 

[DavesMower&Saw]

Which bearing went? the wrist pin bearing or crankshaft bearing?

What you're describing is pretty typical wear on the cylinder for saw of that age. I'd get a set of crank seals, new fuel line, impulse line if needed, cylinder gasket, and a OEM piston either new or used, and new set rings if you choose used.

 

[641workmaster]

The crank cracked and shaved the wrist pin. I have a used crank available. I think the cylinder will clean up nice. Is there a reason to use a Stihl piston/ring kit or will the generics work as well?

 

[Steveo_supremo]

Meteor pistons are excellent. I have them in all but one of My saws. Get them from Baileys or Northwood saw. The 034 Super takes the same piston as a 036. I would just order a 036 piston to avoid confusion.

 

[641workmaster]

I found a donor saw with a good crank and new seals. The cylinder has some aluminum smear but I should be able to clean it up with muratic acid. The original cylinder mentioned above actually had a deep groove in the compression zone.

So upon examination of this new piston, it has some normal carbon buildup on it but the skirts have rubbed on both sides(hence the buildup in the cylinder). This is my first attempt at rebuilding and I'd like to know if this is caused by stuck rings, normal old saw use, or something else? Can I clean up the piston and stick new rings in it? or is it shot?