Stihl 034 rebuild

[rw05]

So today I picked up a new to me stihl 034 that needs some work. There’s a tag on it from a repair shop stating it needs piston and cylinder replacement. Are there any decent aftermarket kits or should I stay with oem? Also is there anything else I should be doing when I tear it apart? I plan on keeping the saw so I want to do it right.

 

[bullittman281]

The 034 is a neat saw. I just finished one of these and an MS360. Plan on main bearings. The plastic cage in the bearings is garbage in WILL give up the ghost. I had one running on a Meteor piston/cylinder. Not sure about performance but with no base gasket it ran fine. Tear it apart and see what it needs. The Stihl case separator tool clamps onto the bar studs and presses the crank out of the PTO side main bearing. You'll need new seals and bearings. Flywheel side uses a standard 202 (I think, check with bearing house) bearing. Clutch/PTO side is special. I'd pull it all the way down and see what you have. When going back together plan the attack carefully and use dry ice to help with the press fits. Its possible to use the clutch to help pull the crank though the Clutch/PTO bearing for final assembly of the bottom end. Bearings are no place for a hammer. I just did an OEM Piston/Cylinder on an MS360. My cost was ~$340 out the door. Its really hard to justify the high cost. Good or bad I have a new OEM rebuilt 360 but it was stupid expensive.

Bullittman

Edit: Looks like a first post. Welcome to the board.

 

[northmanlogging]

So today I picked up a new to me stihl 034 that needs some work. There’s a tag on it from a repair shop stating it needs piston and cylinder replacement. Are there any decent aftermarket kits or should I stay with oem? Also is there anything else I should be doing when I tear it apart? I plan on keeping the saw so I want to do it right.

Just get the OEM stuff. I've heard ok things about Meteor, but you still take a gamble, OEM works every time.
if you want to do it right, split the case and do bearings and seals while you're at it. Then have it vacuum tested to make sure there are no air leaks.
You can make a judgement call on splitting the case, if it looks like its been straight gassed and the rod and crank aren't cooked a piston and cylinder will do ya fine. if it has... yer looking at full rebuild
The carbs on some of the older 036's can be kind a doofy, there's a funky needle valve that goes bad, its replaceable, but it causes it to go lean/rich without much control

 

[Mad Professor]

Might want to do vac/press test before you tear it down. Will locate any leaks in seals/carb boot/impulse line. Seals come with a Stihl gasket set. When you have popped the old seals out inspect the crank bearings well and decide if you need to/want to replace those. That's a bit more work. Probably want to replace impulse and fuel and oiler lines, fuel filter, and air filter too if it's worn. Rebuild carb with an OEM kit. Stihl has an upgrade kit for the clutch which uses a larger bearing for the drum. I don't see a bar with the saw but those can usually be reconditioned by truing the rails up.

You may be able to salvage the cylinder if the plating is intact. Post some cyl pictures when you've got it apart and read up on ways to remove aluminum transfer.

I still have NOS OEM 034 cylinders listed in the trading post here. Just 034 cylinder 46mm no pistons, $75 plus the ride. Meteor pistons are ~$35, Stihl ~$80

https://www.arboristsite.com/threads/034-stihl-cylinder-nos-oem.355438/

 

[Maintenance supervisor]

I put a hyway 48mm pop up piston kit on mine, I bought the kit cheap from a member on here.
The saw is significantly stronger then stock and pulls a 25" bar with authority. I've bucked firewood and dropped trees with it and so far so good.
I believe that I still have the oem cylinder in a box,( I keep most of the ones I remove) ,if its still usable and your interested I'll send it your way for 10 bucks + shipping.
There's also a couple of good threads on doing an 044 hybrid with that saw, they are rippers!

 

[rw05]

So I got it somewhat cleaned up and broken down this morning. Does the scoring on intake and exhaust side of the piston indicate anything?

 

[Maintenance supervisor]

Usually straight gas will be the scoring of the entire piston, like yours.

 

[cuinrearview]

Looks like ******/old mix.

 

[rw05]

So I cleaned the cylinder using acid, steel wool, and finished it off with a light honing. Does it look like it’s good enough or should I keep going. I’m afraid I’ll damage it if I keep going.

 

[rw05]

And on an unrelated note that I’m pretty excited about the guy I bought this 034 decided to sell me this 440 magnum for $100. It will actually run it’s just low compression.

 

[Maintenance supervisor]

Oh man your pulling them in now! Good for you, that cylnder looks pretty good, you can clean it up even more with a scotch bright pad green from ace hardware or somewhere.
Then wash with hot water and dish soap, lube walls with 2mix and assemble.

 

[rw05]

Oh man your pulling them in now! Good for you, that cylnder looks pretty good, you can clean it up even more with a scotch bright pad green from ace hardware or somewhere.
Then wash with hot water and dish soap, lube walls with 2mix and assemble.

This is the only place that’s concerning me.

 

[ballisticdoughnut]

This is the only place that’s concerning me.

Looks like the acid may have found a flaw in the plating. I've had this happen on two cylinders, needless to say I no longer use acid to remove aluminum transfer.

 

[huskihl]

This is the only place that’s concerning me.

It’ll be fine. Make sure the edges of the plating aren’t sharp

 

[huskihl]

Looks like the acid may have found a flaw in the plating. I've had this happen on two cylinders, needless to say I no longer use acid to remove aluminum transfer.

If acid found a flaw in the plating, the flaw was already there…

 

[Mad Professor]

This is the only place that’s concerning me.

Can you catch a fingernail on those and/or do they seem to be through the plating? Intake side is not as critical as ex side. If you do have any imperfections in the plating don't use acid on those spots, it will get underneath and eat away the cylinder under the plating.

Rather than steel wool I like to finger sand using wet/dry sandpaper and solution of dish soap. Try to stay away from too coarse of grit so you don't scratch things up.

Some pics of a 036 I got for free, it got straight gassed, piston was toast the cat concurred, cylinder cleaned up nice.

Last picture shows the 034/036 clutch upgrade kit with the larger bearing.

 

[Maintenance supervisor]

This is the only place that’s concerning me.

My ProMac800 has a good 4mm chunk in about the same place, its a good saw and runs well.
As stated smooth the edges of the defects.

 

[rw05]

It feels smooth so I guess I’m going with it. In the meantime I’ll search for another cylinder for the next rebuild if it ever needs one. Stihl is nla on the 46mm piston and cylinder.

 

[bullittman281]

It feels smooth so I guess I’m going with it. In the meantime I’ll search for another cylinder for the next rebuild if it ever needs one. Stihl is nla on the 46mm piston and cylinder.

The top covers changed a bit but just use an MS360 cylinder. Its bigger anyways.

 

[Patrick1903]

And on an unrelated note that I’m pretty excited about the guy I bought this 034 decided to sell me this 440 magnum for $100. It will actually run it’s just low compression.

I’ll give you 150 for it.