Stihl 029 super to 039 conversion

[kkemp]

I have a stihl 029 super that was givin to me . They ran outboard boat oil in it and toasted the piston and cylinder. Should I go with a 039 p&c ? How much difference will it make vs the 029? Also plan on a muffler mod if i do it . Thanks

 

[Likesaws]

Go with. 039 no reason not to, lots more power. Open the muffler
as much as you can, drill out baffles inside muffler and open as much as you can behind deflector. Trim corner of deflector off to,, will increase opening. Put in larger opening screen to keep bugs out. I'm sure you will like it as a 039.

I try to muff mode most all saws. Weed eater too.

 

[kkemp]

How big of a bar would it run ? I muffler mod all my saws to .

 

[Czed]

I installed a couple of the complete 390 engines of ebay 69.00. If i remember right just had to drill a hole for decomp with limiters pulled and a muff mod run much better than a 290 one guy runs a .325 24 inch bar no problem just the 390 topends are reasonable too.

 

[Czed]

Did those about two years ago still running great no issues.

 

[Mark71gtx]

This is how I do mine. If you drill into the center they get really loud... these are the pictures I send to people before performing this surgery to let them know what they are getting. I just use a drill, file, and a cut off wheel to do this mod. They really do run strong. I usually fit them with a 20" bar with 3/8" full comp. Without the muffler mod the saw is a real dog. I was very pleased with the outcome of this mod. It is hard to believe the difference that mid makes.

 

[kkemp]

Is the decomp needed or can I just delete it ? Not sure how hard those pull over .,

 

[Czed]

I don't think it's needed some of the topends i bought had the plug spare if you wanted to use it and alot of people have had those Chinese decomps leak or fail completely i don't use them anymore.

 

[Czed]

if you go chinese and want to upgrade rings check your new piston with the old rings for thickness only not diameter some chinese pistons use different ring sizes than oem cabers are designed for oem applications.

 

[Czed]

View attachment 45003 View attachment 45004 View attachment 45005
This is how I do mine. If you drill into the center they get really loud... these are the pictures I send to people before performing this surgery to let them know what they are getting. I just use a drill, file, and a cut off wheel to do this mod. They really do run strong. I usually fit them with a 20" bar with 3/8" full comp. Without the muffler mod the saw is a real dog. I was very pleased with the outcome of this mod. It is hard to believe the difference that mid makes.

You're right I've welded a couple of mufflers up that they've cut the center out of. I've done several similar to yours i think it's the best route.

 

[Mark71gtx]

I have never put a decomp on one. If the saw had the hole already there for it. I would consider it, but they normally don't, so why bother...

 

[kkemp]

if you go chinese and want to upgrade rings check your new piston with the old rings for thickness only not diameter some chinese pistons use different ring sizes than oem cabers are designed for oem applications.

Ok. .thanks for the tip . I'm a big fan of caber rings. I pretty much always use them on aftermarket pistons..

 

[kkemp]

View attachment 45003 View attachment 45004 View attachment 45005
This is how I do mine. If you drill into the center they get really loud... these are the pictures I send to people before performing this surgery to let them know what they are getting. I just use a drill, file, and a cut off wheel to do this mod. They really do run strong. I usually fit them with a 20" bar with 3/8" full comp. Without the muffler mod the saw is a real dog. I was very pleased with the outcome of this mod. It is hard to believe the difference that mid makes.

. I'll definitely be looking at this when I start on the muffler .

 

[Wood Doctor]

Lots of work is involved when rebuilding a clam shell engine or upgrading it to a larger bore. I did it once with a 310 to a 390 and I doubt I would do it again. You will have parts all over the place and when it's all taken apart, you will wonder where the saw went. However, it does eventually go back together and while you are at it, you may run into worn out bearings and seals. Keep an eye on that.

Good luck on the rebuild. Here's what mine looked like when complete:


While I was at it, I made a pull cord handle out of white oak. I still use it. This saw now has about the same power as my MS 361, but it weighs more.

 

[kkemp]

Lots of work is involved when rebuilding a clam shell engine or upgrading it to a larger bore. I did it once with a 310 to a 390 and I doubt I would do it again. You will have parts all over the place and when it's all taken apart, you will wonder where the saw went. However, it does eventually go back together and while you are at it, you may run into worn out bearings and seals. Keep an eye on that.

Good luck on the rebuild. Here's what mine looked like when complete:


While I was at it, I made a pull cord handle out of white oak. I still use it. This saw now has about the same power as my MS 361, but it weighs more.

that is the truth alright . Lol . I've only worked on 1 clamshell and it was a small challenge .

 

[stihl_head1982]

that is the truth alright . Lol . I've only worked on 1 clamshell and it was a small challenge .

Do the 029/039 swap. (Forget the decomp) you don't really need it. Plug the hole and never look back.When you do the complete swap. Plan on replacing the fuel line, fuel filter and impulse (use OEM lines and filter -- you will be very pleased). If yours is not a 029 super it won't have the compensating carb. The aftermarket Chinese ones I've tried worked flawlessly. Do the muffler mod -- but remember to retune your carb or you will be replacing the cylinder because of a bad tune.I would use the caber rings as have been mentioned -- to me its a must on these swaps. I've done scores of these and just did one for a friend and he loves it. He runs a 20" bar with a skip chain and it performs quite well in hard wood.

When sealing the pan use a quality sealer that will resist gas and oil. Dirko sealant can be purchased on line or I've used Yamabond a number of times as well. I put a thin layer of sealant on the seal pockets where the seals engage the clam shell house (top and bottom =extra insurance). If I had a 029 or an 029 super -- I'd be ready to swap it before Christmas! Enjoy!

 

[BigRed96]

Just buy a plug for the decompression valve plug, unless you want to drill a hole in you plastics. I plugged mine on both of the 290/390 conversions I have done. I would recommend using the Hutzl 039/MS390 big bore kit listed on ebay that comes with piston,cylinder,seals,bearings,etc. As mentioned before don't use the aftermarket lines. You will need a bearing puller to remove the bearings from the crank. I believe you can borrow the tool from AutoZone for like a $50 deposit. I would also advise you to vacuum test/pressure test the engine before completely reassembling the saw. I converted my saw to a rim sprocket in 3/8 and ran 3/8" 24 inch bar without issue. I will add a video with the 24" on it. The one I built for my brother runs 20" and is a beast. As mentioned use a good fuel/oil resistant sealer. Run Caber rings, and I reused my factory Stihl piston circlips.

 

[kkemp]

Is a oiler upgrade necessary to run a 24 in bar ?

 

[BigRed96]

It depends on what year your 290 is. Mine was older so I had to upgrade the piston to a newer version. Real old thread over on another site. Tells you how to find out how old your saw is and helps determine whether or not you need to upgrade. After that it seemed to oil fine.

 

[BigRed96]

I'm not sure if we are allowed to post links over to the other site or not. Go to there search and type in MS 290 oil pump. MS 290 oil pump is the name of the thread. Read it, it will help you figure out which piston you oil pump has.