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A Dying Chainsaw's Last Words #2: Top End Rebuild

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Blog entry by woodshopmike posted 04-24-2014 01:36 PM 2494 reads 0 times favorited 14 comments Add to Favorites Watch
« Part 1: Carb Rebuild Part 2 of A Dying Chainsaw's Last Words series no next part

Unfortunately for me, rebuilding the carburetor was not enough for my 026. Herein lies the tail of rebuilding the engine of my Stihl 026. I think this has something to do with the problem…

This post jumps right into the process which is wayyyy to lengthy with too many pictures to rewrite. Follow the link to check out the full process.

Thanks for readin’ y’all, have a great day!

-- www.woodshopmike.com, www.woodshopmikestudio.etsy.com



14 comments so far

View kaerlighedsbamsen's profile

kaerlighedsbamsen

1177 posts in 1176 days


#1 posted 04-24-2014 07:40 PM

Your carburetor looks allmost identical to the one on my chainsaw. It would (sometimes) start in idle but died as soon as given any gas. Had it appart about 10 times and couldent find the fault. Then took it TOTALLY appart and the greyish round metal thing next to where it says M81 had to go as well. Was able to pry it out with an awl.

This revealed a second strainer that was full of debris. Reassembled all and got the gray metal disc in place by just punching it with a metla rod nearly the same diameter.

After that it has been running like a dream.
Hope this helps!

-- "Do or Do not. There is no try." - Yoda

View woodshopmike's profile

woodshopmike

222 posts in 1126 days


#2 posted 04-24-2014 07:49 PM

No kidding! I thought about trying to pry that out but figured I shouldn’t. Man, I know what I’m doing when I get home!

Thanks pal, I’ll post once I try that and let you know if it did the trick!

-- www.woodshopmike.com, www.woodshopmikestudio.etsy.com

View kaerlighedsbamsen's profile

kaerlighedsbamsen

1177 posts in 1176 days


#3 posted 04-24-2014 08:30 PM

Only happy to help!
Note: Our carburetors are of different make but looks like clones inside. So no guarantee for success..
If this can save this Stihl you are going to get happy about it! Great, german stuff. Looking forward to hear about the results.

-- "Do or Do not. There is no try." - Yoda

View Jim Jakosh's profile

Jim Jakosh

17154 posts in 2568 days


#4 posted 04-24-2014 08:50 PM

Debris in any engine will give you fits. Usually you can clean it without pulling out plugs like that, but good thing you did!!

Thanks for this post. I have an old Remington that I just loved and it was super loud when running. Now it is hard to turn over and I think I may have a real scored piston and cylinder wall or a broken ring. I should do what you did when I get some time. I always ran regular 2 cycle oil at 20:1 ratio and now I have been using pure synthetic at 50:1. I wonder if that old saw needed more lubrication

Thanks, Jim

-- Jim Jakosh.....Practical Wood Products...........Learn something new every day!! Variety is the Spice of Life!!

View woodshopmike's profile

woodshopmike

222 posts in 1126 days


#5 posted 04-25-2014 01:04 PM

I had actually been running 100:1 off a recommendation from a long time saw guy. The stuff really just protects the engine more since it’s a heavier oil. I haven’t seen a degradation in performance. If you think about it, it will actually increase your compression since there is a thicker oil “rubbing” around the piston rings.

-- www.woodshopmike.com, www.woodshopmikestudio.etsy.com

View woodshopmike's profile

woodshopmike

222 posts in 1126 days


#6 posted 04-25-2014 01:12 PM

To no avail could I remove the cover you mentioned. I was using a dental pick and couldn’t catch an edge to pry it free. When using the awl, did you deform the cover in any way? I’m sure I could smack the awl with a hammer to make it bite into the cover, but then I could screw up the cover that way.

Regardless, I fiddled with the carb settings more this morning and the saw seems to lack… @$$ There is no power in the cut. I tuned the saw for the high rev between blubbering and the saw burping from running too lean. Even when the saw was lean it didn’t sound like it was running near as fast as my husky 55 or as fast as I remember the 026 running a few years ago. Anyways, the saw will just totally bog down in the cut. What’s up with that?

-- www.woodshopmike.com, www.woodshopmikestudio.etsy.com

View Dallas's profile

Dallas

3599 posts in 1950 days


#7 posted 04-25-2014 02:48 PM

Actually, 40:1 is thicker than 50:1 which is thicker than 100:1.

Remember, this is ounce : ounce ratio. The “100” refers to the amount of gas in a ratio with the oil which would be “1” ounce

That’s why 2.6 oz of oil make 50:1 and and 3.2 ounces makes 40:1 per gallon of gas.

Modern 2 cycle oils only contain oil as the carrier. The part that is carried is synthetic. It use to be that 2 cycle oil was totally petroleum based, way back in the days of the Homelite C5 8:1 mix, even up into the 1970’s as more synthetics were used the ratio spread got higher.
I’m certain your Stihl calls for a 50:1, but I run 40:1 in everything because I’m lazy and that’s the ratio that will work in everything.

-- Improvise.... Adapt...... Overcome!

View woodshopmike's profile

woodshopmike

222 posts in 1126 days


#8 posted 04-25-2014 03:03 PM

ooohhhh. Well now I feel really smart!

-- www.woodshopmike.com, www.woodshopmikestudio.etsy.com

View kaerlighedsbamsen's profile

kaerlighedsbamsen

1177 posts in 1176 days


#9 posted 04-25-2014 07:35 PM

From your description it sounds just like mine did before cleaning the hidden strainer. You need to deform the metal in the cower. It is wery soft (like lead or tin) and is only pressed in place.
To be sure that all the narrow channels are totally celan use nylon fishing line.

A saw like that should go 15.000+ rpm with no trouble and get at deeper sond when cutting.

Btw for cleaner air consider using this gas alternative: http://www.aspenfuel.co.uk/products/environmental-fuels/aspen-alkylate-petrol/aspen-2-alkylate-petrol-pre-mixed-501/

Good luck!

-- "Do or Do not. There is no try." - Yoda

View woodshopmike's profile

woodshopmike

222 posts in 1126 days


#10 posted 04-25-2014 07:56 PM

Thanks for following up. I’ll give it a try!

-- www.woodshopmike.com, www.woodshopmikestudio.etsy.com

View woodshopmike's profile

woodshopmike

222 posts in 1126 days


#11 posted 05-16-2014 05:28 PM

I know it’s been a while, but still no success. I broke down and bought a new carb for the saw. It should be here middle of next week, so we’ll see how things go.

I tried removing the aluminum plug to reveal the hidden strainer, but saw no such screen under the plug. I also managed to deform the plug to the point that it no longer seals sufficiently and the saw will not run currently. Looks like a new carb is my only option at this point.

I’m keeping my fingers crossed!

-- www.woodshopmike.com, www.woodshopmikestudio.etsy.com

View Dallas's profile

Dallas

3599 posts in 1950 days


#12 posted 05-16-2014 06:32 PM

After you get the new carb on, (I never try to fix one anymore, a new one is too cheap). Check the compression. A lot of Stihl’s won’t ever start at less than 125 psi. Even at that compression they are a bugger to start.
From looking at the picture again, that piston and ring are scored beyond redemption. Most likely the cylinder can be cleaned up.
A piston, ring and pin kit is less than $50, which is a lot less than a New version of the .026.
Touch up the cylinder with a brake hone and clean up the glaze by hand with a few swipes of a wet piece 400g sand paper.
Remember, you want an angle on the honing pattern.

Oh, yeah, to seal the plug in a carb I use a touch of 3M RTV black, but again, I quit rebuilding these little ZAMA and other 2 stroke carburetors. Buying repair/rebuild kits takes at least 3 per carb and that is the cost of a new or professionally rebuilt unit.

-- Improvise.... Adapt...... Overcome!

View woodshopmike's profile

woodshopmike

222 posts in 1126 days


#13 posted 05-16-2014 07:43 PM

Dallas,

I replaced the piston and cylinder. I wasn’t even going to try replacing the rings or honing the cylinder, there are some pretty deep grooves in the cylinder wall. Thanks for the tips on honing a cylinder and what to use for plugging the carb! I was going to just toss the carb out, but I’ll hold on to it and remember your tip just encase I get into a bind.

-- www.woodshopmike.com, www.woodshopmikestudio.etsy.com

View Dallas's profile

Dallas

3599 posts in 1950 days


#14 posted 05-16-2014 08:17 PM

I would still check the compression. something isn’t kosher in boogertown.

You should be able to drop a few drops of gas down the intake of the carb and it should fire and run. At least for a few seconds.
I ask again, do you have a nice blue spark? at least yellow, although that won’t work for long. It indicates the gap is too large between the flywheel and the coil, or it could be that the coil degraded that much over the years.

Pretty much you use the same trouble shooting methods to trouble shoot these things as you do to trouble shoot an old car.

The best advice I can give is that you find the method of trouble shooting that works for you and stick to it. Never take for granted any of the steps involved.

Now, with all that being said, if the engine will run with a few drops poured down the carburetor, check that you put the fuel lines back on correctly. If the primer bulb is stiff, hard to pump or won’t work at all, the fuel lines are backwards.
The 026 fuel line diagram is available on line.
If it still doesn’t work, dig out the fuel filter, (You are suppose to replace it every year).
I now have 3 nice Stihls sitting here that ran with no problems for years. This spring I got these in and 4 other saws. All of them have degraded fuel lines which plug up the carbs and/or plugged fuel filters.

-- Improvise.... Adapt...... Overcome!

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