Worst transfer yet! 026 resurrection...

[JB Weld]

I had a guy at church bring me two saws the other day. A MS290 and a 026AV. He said I could keep the 026 if I could get the 290 running. I told him I would see what I could do.... [emoji19]

It took me about 30 minutes to get the 290 running. It had a dirty carb. He got his saw back and was happy as could be. I gave him strict instructions to run it dry before he put it up next time and down the road we go.

A couple of days ago I got that 026 on the bench and started breaking it down. It had the worst piston I have ever seen. It took me about an hour to get the transfer out of the cylinder using my jack leg version of the "Mastermind" method. I did get back to a serviceable condition though. Hopefully I will get some time today or tomorrow to put it back together. I am thinking about opening the muffler a bit. I have to do a little research first though.

Here is a picture of the piston I removed. It had transfer to the intake as well as the exhaust. There is a couple spots where the aluminum has the rings buried in the ring groove. I know some of you guys have seen worse, but I am only a jackleg hobby mechanic and this is my worst yet. [emoji13]

 

[s sidewall]

Pretty

Steve

 

[Mad Professor]

That looks like a 036 piston from a saw I "saved". Glad to see you took the time on fixing the 026.

Did you get before and after pictures of the cylinder? If so post them so others can get an idea how bad things can look and still be salvageable.

There is a person on ebay with OEM 44mm 026 stihl pistons about same as dealer price, not sure what meteors are now?.

A muffler mod and setting the squish will wake it up. Be sure to check the seals/rubber/hoses/carb even if owner straight gassed it. Does the carb have Hi adjustment?

 

[JB Weld]

I did not take pictures of the cylinder, but the transfer was THICK. It took me about an hour to remove all the transfer. I just take my time and sand it all out. I was scared to death the first time I tried it. I just knew I was going to ruin the jug, but that Husky is still alive and well cutting firewood for my buddy.

I am using a Farmtec piston kit. It comes with base gasket, exhaust gasket, wrist pin/clips, needle bearing, and new piston. All the hoses are in great shape. Overall the saw is in really good condition. I went completely through the carb. It is like new again, and yes it does have the "Hi" adjustment.

On the Squish, I have done that with a golf cart engine. In that case, all I did was use sealant instead of a base gasket. That gave me a tiny bit more compression. I just had to make sure my piston top still had clearance by squishing a piece of soft solder between the top of the piston and the edge of the top of the cylinder. Is that what you are calling "the squish"?

 

[lone wolf]

I did not take pictures of the cylinder, but the transfer was THICK. It took me about an hour to remove all the transfer. I just take my time and sand it all out. I was scared to death the first time I tried it. I just knew I was going to ruin the jug, but that Husky is still alive and well cutting firewood for my buddy.

I am using a Farmtec piston kit. It comes with base gasket, exhaust gasket, wrist pin/clips, needle bearing, and new piston. All the hoses are in great shape. Overall the saw is in really good condition. I went completely through the carb. It is like new again, and yes it does have the "Hi" adjustment.

On the Squish, I have done that with a golf cart engine. In that case, all I did was use sealant instead of a base gasket. That gave me a tiny bit more compression. I just had to make sure my piston top still had clearance by squishing a piece of soft solder between the top of the piston and the edge of the top of the cylinder. Is that what you are calling "the squish"?

What kind of compression did you end up with after all that?

 

[JB Weld]

The saw is still in pieces. I will post compression results after I get her all back together.

On the golf cart, I do not remember. It was a low compression engine and I was just trying to get all I could out of it. It is still chugging away working on a tree farm in North Central Arkansas. Like stated above. I am a jack-leg mechanic who works in the garage of repair and despair (for a hobby). I work on just about anything.

 

[jr27236]

I didnt like the circlips that came with the Farmertec and reused the OEM clips. If they are fine I'd do the same in your case.

 

[grizz55chev]

The saw is still in pieces. I will post compression results after I get her all back together.

On the golf cart, I do not remember. It was a low compression engine and I was just trying to get all I could out of it. It is still chugging away working on a tree farm in North Central Arkansas. Like stated above. I am a jack-leg mechanic who works in the garage of repair and despair (for a hobby). I work on just about anything.

Don't forget to pressure vac test or you will fry your new piston.

 

[old guy]

It looks like that one was straight gassed.

 

[Mad Professor]

I did not take pictures of the cylinder, but the transfer was THICK. It took me about an hour to remove all the transfer. I just take my time and sand it all out. I was scared to death the first time I tried it. I just knew I was going to ruin the jug, but that Husky is still alive and well cutting firewood for my buddy.

I am using a Farmtec piston kit. It comes with base gasket, exhaust gasket, wrist pin/clips, needle bearing, and new piston. All the hoses are in great shape. Overall the saw is in really good condition. I went completely through the carb. It is like new again, and yes it does have the "Hi" adjustment.

On the Squish, I have done that with a golf cart engine. In that case, all I did was use sealant instead of a base gasket. That gave me a tiny bit more compression. I just had to make sure my piston top still had clearance by squishing a piece of soft solder between the top of the piston and the edge of the top of the cylinder. Is that what you are calling "the squish"?

Yes

 

[pioneerguy600]

Be very careful when taking the squish measurements on the 44 mm jugs when not using a gasket. These jugs have a very narrow ring right at the cylinder wall to the cylinder head juncture. Usually there is only around .015 or less clearance between the piston and that ring at TDC when run without a gasket. I have run a few with .015 clearance but that is as close as I will run them, if less clearance I cut that ring out to gain greater clearance. Good luck with your build,enjoy.

 

[JB Weld]

Thanks for all the advice guys! I decided to use the perfectly good base gasket I had laying on the bench. [emoji6]

I will save "the squish" experiment for my buddies 026 sitting in a box in my garage. [emoji106]

I almost got her back together before supper. All I need to do is get muffler ported/installed and tune the saw. Hopefully I can finish up tomorrow evening.

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[Mad Professor]

Be very careful when taking the squish measurements on the 44 mm jugs when not using a gasket. These jugs have a very narrow ring right at the cylinder wall to the cylinder head juncture. Usually there is only around .015 or less clearance between the piston and that ring at TDC when run without a gasket. I have run a few with .015 clearance but that is as close as I will run them, if less clearance I cut that ring out to gain greater clearance. Good luck with your build,enjoy.

Thanks for that information. Will be careful checking on 026

Stock base gaskets are ~ 0.020", so a 0.005-0.010" shim in it's place would be about right.

 

[pioneerguy600]

A .005 will in most cases give enough clearance without cutting the ring out, these small diameter bore cylinders can be run with a tighter squish. Anything over .019 would be very safe. I have a few 026`s running just .015 and as long as there is no buildup of carbon on the piston crowns then thee will not be any head slapping problems.

 

[Mad Professor]

A .005 will in most cases give enough clearance without cutting the ring out, these small diameter bore cylinders can be run with a tighter squish. Anything over .019 would be very safe. I have a few 026`s running just .015 and as long as there is no buildup of carbon on the piston crowns then thee will not be any head slapping problems.

Another thought. How wide is the "ring"? Maybe just take a bit off the top edge of the piston, sort of a poor mans popup.

 

[pioneerguy600]

That could be done also but it messes up the port timing just a little, not that that would be an end all to the experiment. I prefer to cut the ring out and also lower the jug a bit more, say .010. That and a muffler mod really wakes them up. Then a few hours grinding out the ports can lead to a very powerful fast cutting saw, like the ones I run for personal use.

 

[Mad Professor]

That could be done also but it messes up the port timing just a little, not that that would be an end all to the experiment. I prefer to cut the ring out and also lower the jug a bit more, say .010. That and a muffler mod really wakes them up. Then a few hours grinding out the ports can lead to a very powerful fast cutting saw, like the ones I run for personal use.

I don't want to hijack the thread but now you have me thinking as I have a complete 44mm 026 that needs at least a piston and I have a NOS OEM P/C.......

If you delete the base gasket that alters the timing in the opposite way of trimming the top of the piston. Where do you want the timing to end up on a 026 for a work saw for the various ports and besides widening the int and ex what do you do to reshape things? I can take 0.010" off the cyl base easy with some paper on some plate glass but don't have the equipment to remove the ring at the top, how is the best/easy way to do the latter for a "cave man" porter?

 

[JB Weld]

Hijack away matey! [emoji482]

I have another 026 waiting in a box and I am very interested in giving it the squish! This is what I love about this site. It is full of Chainsaw PhD's!

I too am a caveman mechanic!

 

[pioneerguy600]

I don't want to hijack the thread but now you have me thinking as I have a complete 44mm 026 that needs at least a piston and I have a NOS OEM P/C.......

If you delete the base gasket that alters the timing in the opposite way of trimming the top of the piston. Where do you want the timing to end up on a 026 for a work saw for the various ports and besides widening the int and ex what do you do to reshape things? I can take 0.010" off the cyl base easy with some paper on some plate glass but don't have the equipment to remove the ring at the top, how is the best/easy way to do the latter for a "cave man" porter?

We like to increase the compression a bit by lowering the exhaust port, deleting the base gasket lowers the port some, cutting/shaving the cylinder base lowers it more and this will increase compression and at the same time it increases intake duration, a win - win situation. The actual port timing numbers will vary a bit from one cylinder to the next as it will also from one manufacturer to the other. For the 026 stock exhaust is usually around 94 deg and can be gotten down to 97-98 with a gasket delete and a bit of base shaving. I have found that the closer one can get the exhaust to 100 degrees the better they work for an everyday saw. Now there are many 026`s out there that have much more or lower exhaust port timing with compression numbers in the 250 lb range but a lot more work has to be done to them to get there, usually more than the average owner can perform.
Removing the ring at the top requires either a lathe and boring bar or it can be cut by hand using a cutter bit embedded in anything from an old piston to a specially sized turned dowel/mandrel, this requires some precision measuring and tooling not everyone has at their disposal. The ring can also be scraped out with just a plain wood chisel if the person doing so has the ability to handle a cutting/scraping tool with dexterity and precision, been done by a good many for 50 years or more on chainsaw engines, not only on 026`s...

 

[JB Weld]

I got her back together today, and all is well. I ended up porting the muffler. She tuned nicely. I tune by ear, so I have her 4 stroking a bit and blowing a tiny bit of smoke. She cuts good and sounds great. Thanks for all the input guys.

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