Stihl 029 to 039 guidance on teardown and upgrade

[ADK_XJ]

Hey all, an old family friend insisted on "paying me" for a firewood delivery and gifted me a 90s Stihl 029 that he said would only start/run at full choke.

I opened it up and see the piston badly scored. I have done basic maintenance on Stihl saws before but never major teardown...in searching the forum it looks like the 029 to 039 upgrade is a common and straightforward one.

Is there any existing guide to the teardown and rebuild process on this saw? None of the cylinder kits I'm looking at come with instructions. Any thing I should absolutely do while it's torn apart?

I have 3 other fully functioning saws so this is more for kicks and education...I can take my time. Here's where it stands:

 

[HarleyT]

I am sure that youtube has a few videos. The 029/039/ms290/ms31/ms390 are all basically the same saw.

 

[irhunter]

What I do:

1. I always pressure/vac test before pulling jug.
2. Never buy any parts until I have tried to remove aluminum transfer from the jug.
3. Don't replace the jug if I can clean it up.
4. Get the shop manual.

 

[ADK_XJ]

Thanks, without a specific tool, is there any way to pressure test?

The rest makes sense to me.

 

[Mad Professor]

Thanks, without a specific tool, is there any way to pressure test?

The rest makes sense to me.

Mity Vac 8500

 

[a. palmer jr.]

Hey all, an old family friend insisted on "paying me" for a firewood delivery and gifted me a 90s Stihl 029 that he said would only start/run at full choke.

I opened it up and see the piston badly scored. I have done basic maintenance on Stihl saws before but never major teardown...in searching the forum it looks like the 029 to 039 upgrade is a common and straightforward one.

Is there any existing guide to the teardown and rebuild process on this saw? None of the cylinder kits I'm looking at come with instructions. Any thing I should absolutely do while it's torn apart?

I have 3 other fully functioning saws so this is more for kicks and education...I can take my time. Here's where it stands:

The very first thing you should do is after tear down is clean up every part that you're going to re-use. Clean all plastics, the engine parts, other than piston and cylinder, carb, ignition, etc.
I usually don't bother with the initial pressure/vac test because I'm not gonna use most of the parts I'm putting back on the saw, such as, crank seals, pulse and usually fuel lines, p-c kit. I usually get a tube of Dirko sealer to seal up the bottom plate when I'm done with the engine.
As this is an older, not high dollar saw I generally don't try to find OEM parts except for maybe the fuel line. Trying to OEM the complete saw makes it a high dollar project.

 

[smallengineredemption]

If you need any parts lmk I sent u a pm for my YouTube, also I sell meteor if you want a piston of top end lemme know asap if I don't have it I'll order it when I order next week

 

[smallengineredemption]

If you need any parts lmk I sent u a pm for my YouTube, also I sell meteor if you want a piston of top end lemme know asap if I don't have it I'll order it when I order next week

Your carb should be a k10-hd kit typically on this series...

 

[irhunter]

I usually don't bother with the initial pressure/vac test because I'm not gonna use most of the parts I'm putting back on the saw

I like to test before full disassembly cause (1) it costs nothing, (2) takes 5 minutes, (3) I just really like to know what killed the piston.

It is not that I expect to commonly find some intel which will be critical to the build...but, I just like to know.

+1 on get it clean

+1 for cleaning and reusing OEM jug


Roy

 

[smallengineredemption]

I like to test before full disassembly cause (1) it costs nothing, (2) takes 5 minutes, (3) I just really like to know what killed the piston.

It is not that I expect to commonly find some intel which will be critical to the build...but, I just like to know.

+1 on get it clean

+1 for cleaning and reusing OEM jug


Roy

Preach it!!!!!

 

[dmb2613]

They are very popular saws with firewood cutters , ans EZ to rebuild 390 cylinder and pop up piston open up the muffler and advance the timing 1/3 of the keyway . It will cut with a 440 , new seals and rubber. Check the bearings I have done maybe 100 of them
Could do more if they didnt last so long lol

 

[smallengineredemption]

They are very popular saws with firewood cutters , ans EZ to rebuild 390 cylinder and pop up piston open up the muffler and advance the timing 1/3 of the keyway . It will cut with a 440 , new seals and rubber. Check the bearings I have done maybe 100 of them
Could do more if they didnt last so long lol

Let's get a video of you doing that flywheel key, my hands ain't that steady lol why I can't port dern nerve damage. I just converted a 290 to a 390

 

[dmb2613]

I am 67 years old and dont have a clue about a video lol

 

[smallengineredemption]

I am 67 years old and dont have a clue about a video lol

Love it!!! Ya I'm trying to figure it out myself and I'm only 37... touch screen what my phone has no buttons and I can send ppl letters on it....

 

[Pioneer]

Not the hardest saw to assemble, but you will find everything has to be done in a specific order. Pay attention as to how the old sealant on the crank housing was applied, duplicate this during your assembly and you should have no problems with air leaks. As mentioned about the fuel line, the cheap chinese ones have a tendency to dissolve. Of course do a carb kit and any other normal maintenance items during the build. The muffler is a poor design and does not lend itself to a mod easily, the wonky mounting screw spacing is to blame.
Not worth putting a lot of money into this series of saw, maybe find a chinese piston/ cylinder with good reviews and a refund option if it is not going to see a lot of use. The refund option is necessary as quite a few will come with defective cylinder plating out of the box.

 

[shortys7777]

Sorry to bust in on the thread but I did this conversion last year. Ran about 3 cords through it and this year I ran maybe half a cord. No I can't get the thing started and stay running. It starts and runs at half choke but once I pull the trigger it slows down and dies. I am going to try to mess with the carb settings again. I checked the carb cleaner spray method for air leak, took it apart to check the intake boot, checked the fuel lines and filter. All seem good. I did pull the limiters and needed to adjust last year after I ran a few tanks through it. Whats the rule of thumb? turn them all the way in then back out 3/4 turn and go from there?

 

[a. palmer jr.]

Sorry to bust in on the thread but I did this conversion last year. Ran about 3 cords through it and this year I ran maybe half a cord. No I can't get the thing started and stay running. It starts and runs at half choke but once I pull the trigger it slows down and dies. I am going to try to mess with the carb settings again. I checked the carb cleaner spray method for air leak, took it apart to check the intake boot, checked the fuel lines and filter. All seem good. I did pull the limiters and needed to adjust last year after I ran a few tanks through it. Whats the rule of thumb? turn them all the way in then back out 3/4 turn and go from there?

I would go at least one turn to start with..