Mag Rot - How Far Is Too Far?

[Vintage Engine Repairs]

What was the ring gap in the end ?

Haven’t checked yet, just been cleaning the transfer and scrubbing all the carbon off the exhaust and cleaning fins

A before and after picture. I used a fine tipped diamond bit followed by 240 grit, 400 grit and then green scotch bright for a smooth clean finish and to ensure no burrs remain. I found it chipped a bit on the lower and upper portion of the port so smoothed both.

BEFORE:






AFTER:

 

[Vintage Engine Repairs]

BEFORE AND AFTER ZOOMED IN.

it’s very difficult to catch my finger nail on it at all now, before it would grab it every time.

 

[LegDeLimber]

Sure thing! Just soaking in Evaporust to get some of the stubborn carbon off and I’ll have pics up

Tom, How well would you say the Evaporust works at turning the carbon loose?
As you may have noticed, The carbon removal remains a perennial issue that comes up for suggestions.
When looking for something to get carbon out of cylinders, I see this ingredient "EDTA" show up in a few posts around the web.

It seems to be in the Stihl decarbonizer (needed for the"4-mix" engines issues) and then I see people offering the opinion that Evaporust also includes it.
The MSDS that I can find for Evaporust only lists "proprietary" ingredients (roll eyes here)
The Stihl MSDS lists a bit of EDTA also.

I've used a little bit of the stihl decarbonizer and after just leaving to sit it for a while (actually I just forgot about it) it seemed to clean out the worst of an Echo blower cylinder build up.
Most of the crud rinsed out with hot (>135,f) water and a bit of poking with a plastic drinking straw.
oh and Do take note that plastic straws are on the no-no list now!
(so many people are such slobs with their trash, that... sigh)

I will probably try the Evaporust on the next crusty cylinder or head.
I don't suppose ya got any before & after views of the carbon, do ya?
You know how we men folk are such visual creatures! lol

Edit: oh yeah and here are some related links that I found.
https://en.wikipedia.org/wiki/Ethylenediaminetetraacetic_acid

https://m.stihlusa.com/WebContent/CMSFileLibrary/SDS/MSDS-Engine_De-Carbonizer.pdf

Ethylenediaminetetraacetic acid in Evaporust mentioned here
https://www.garagejournal.com/forum/showthread.php?t=69793

https://www.arboristsite.com/community/threads/stihl-engine-de-carbonizer.42116/

 

[Vintage Engine Repairs]

Tom, How well would you say the Evaporust works at turning the carbon loose?
As you may have noticed, The carbon removal remains a perennial issue that comes up for suggestions.
When looking for something to get carbon out of cylinders, I see this ingredient "EDTA" show up in a few posts around the web.

It seems to be in the Stihl decarbonizer (needed for the"4-mix" engines issues) and then I see people offering the opinion that Evaporust also includes it.
The MSDS that I can find for Evaporust only lists "proprietary" ingredients (roll eyes here)
The Stihl MSDS lists a bit of EDTA also.

I've used a little bit of the stihl decarbonizer and after just leaving to sit it for a while (actually I just forgot about it) it seemed to clean out the worst of an Echo blower cylinder build up.
Most of the crud rinsed out with hot (>135,f) water and a bit of poking with a plastic drinking straw.
oh and Do take note that plastic straws are on the no-no list now!
(so many people are such slobs with their trash, that... sigh)

I will probably try the Evaporust on the next crusty cylinder or head.
I don't suppose ya got any before & after views of the carbon, do ya?
You know how we men folk are such visual creatures! lol

Edit: oh yeah and here are some related links that I found.
https://en.wikipedia.org/wiki/Ethylenediaminetetraacetic_acid

https://m.stihlusa.com/WebContent/CMSFileLibrary/SDS/MSDS-Engine_De-Carbonizer.pdf

Ethylenediaminetetraacetic acid in Evaporust mentioned here
https://www.garagejournal.com/forum/showthread.php?t=69793

https://www.arboristsite.com/community/threads/stihl-engine-de-carbonizer.42116/

Hey, well as an example, a piston head had been coated in carbon build up. After 24 hours I could wipe most off, after that rubbing my thumb and a gentle scraping with my nail removed the rest, here is a pic. Before unless I mechanically abraded it away, it would have stayed adhered to the piston - it wasn’t coming off.

I actually had no clue it would work on carbon, I put something in the solution for rust, but it also cleaned all the carbon off too.

as you can see there is only one spec remaining at 11 and one a 3 (imagine a clock face) Before it had a thick layer covering the majority of the piston crown

 

[Vintage Engine Repairs]

Oh I did find a before here!!!

before and after evaporust (and a little rubbing of my thumb and nail)

 

[LegDeLimber]

You do realize that you just (carbon?) dated yourself with analogue clock reference? Still have them myself!
Anyhow. The last piston I cleaned that resembled yours, I put in the ultrasonic and a solution of water and "pine cleaner" soap.
Funny that the real brand here "Pine-Sol" no longer has any pine oil. You have to get the Dollar Store brand to have any pine oil now.
I ran the cleaner intermittently over a several hr span and, with no hand scrubbing, got results that looked like your piston.

You can see a few light gray patches where it bubbled a bit more vigorously (the long ding mark was there when I opened the unit).
Interesting how it "shadowed" around the arrow. I should take a closer look at all the lighter areas.
Not sure if there's a before shot, but it looked like yours, only a little bit oiler.
Got the blower used, but believe this to be 1st/only time apart.
I need to get motivated & measure the squish then decide what path to take with re-assembly.

 

[trains]

Tom, drop the piston down into the cylinder, and measure the gap at the piston skirt end, what measurement are you getting ?
Post it up and we can let you know if you need a new piston, or can just reuse the old one, cant remember what the piston skirt looks like on the exhaust side, is it worn flat etc ?

look for uneven wear on the piston skirt from below, quick visual, then drop into cylinder and measure gap.

T

 

[Vintage Engine Repairs]

Tom, drop the piston down into the cylinder, and measure the gap at the piston skirt end, what measurement are you getting ?
Post it up and we can let you know if you need a new piston, or can just reuse the old one, cant remember what the piston skirt looks like on the exhaust side, is it worn flat etc ?

look for uneven wear on the piston skirt from below, quick visual, then drop into cylinder and measure gap.

T

Hey mate, the skirt is not damaged on the exhaust opening area, it just has 4 corner scoring which is only slightly noticeable either side of the exhaust opening but the majority of the skirt that can be seen through the exhaust port is good. Piston skirt to cylinder wall is 0.1mm / 0.0039”

 

[TheTone]

0.0039" is in the "iffy" zone, but since this is an "economy" rebuild it's got some life left.

 

[Vintage Engine Repairs]

Ok here is the clutch before and after evaporust. No scrubbing, just dropped it in it and left it 24 hours

 

[TheTone]

It's amazing stuff. It's reusable too, although I have found that the potency decreases fairly quickly with each use.

 

[Vintage Engine Repairs]

It's amazing stuff. It's reusable too, although I have found that the potency decreases fairly quickly with each use.

I must be honest in my experience it doesn’t decrease in potency that quickly. However I do degrease / clean each item first as recommended to prolong the life of the liquid, do you do that too? That maybe why?

 

[Sepia]

Ok here is the clutch before and after evaporust. No scrubbing, just dropped it in it and left it 24 hours

View attachment 803474
View attachment 803475



View attachment 803473
View attachment 803476

I have to get some of that stuff! Pretty amazing how well it works.

 

[TheTone]

I must be honest in my experience it doesn’t decrease in potency that quickly. However I do degrease / clean each item first as recommended to prolong the life of the liquid, do you do that too? That maybe why?

The parts are clean, but my Rust Area to Evaporust ratio may be higher.

 

[Vintage Engine Repairs]

Oooo it’s been a while! Anyway this rebuild continues. It’s getting put back together, holds pressure and vacuum, at 6psi with crank spinning.

Looking for the flywheel key and I’ll be darned, my safe location for it clearly wasn’t safe as I can’t remember where I put it. Got one in order from the shop, why not integrate the stupid thing into the flywheel like on the small homeowner saws?

Another plug for @Mattyo ‘s crank tools, absolutely bloody brilliant. They allow for such ease in pulling the crank through the inner race and excellent control when cantering the crankshaft. I finished with a little preload which I think is because I snugged it a little too much, but a gentle tap with the hammer freed it up no problems. It’s an excellent lesson learnt.

 

[L34]

I always put key on magnet of flywheel.

 

[Vintage Engine Repairs]

Most things are back on
Found the original key for flywheel in the shed!

Just tested the ohms and decided to clean up the copper ground and where it connects to the ignition module, it would have been ok, but but there was a degree of corrosion which would only worsen. Once done i had very low resistance when the circuit was complete and no resistance when the saw was on, there were no breaks and no grounding out when it shouldn’t.

 

[Vintage Engine Repairs]

Ok she’s all back together. Just waiting on a new fuel line, oil line and a chain catcher and I’ll test it out

Initial compression is 145psi, not bad when the rings and piston looked the way they did! Gave the plastics a polish too

BEFORE -



AFTER -



Completed saw -

 

[Vintage Engine Repairs]

redid compression test today. A touch over 150 psi. The compression test I did yesterday, I couldn’t give it my all as it was still in bits when I did it.

Very impressed considering the scoring on the piston rings and piston. I must share credit where credit is due - The advice from @trains has proven excellent once again, In fact this rebuild wouldn’t have been half of what it is without his advice - the amount of time and information he has shared teaching me about saws and advice and guidance on rebuilds Is remarkable and massively appreciated. He’s the friend everyone wants but so few are lucky enough to have. As for the compression, It will likely drop 5-10 PSI when the assembly lube has burnt off, but I’m still very happy as I expected 100-110.

 

[Vintage Engine Repairs]

Well here is the final post on this thread!

I got her all back together. Started it and it was crazy lean. Stripped carb cleaned and rebuilt. Over and over. With help from trains the conclusion was to direct attention towards a leak in throttle shaft, as I told him I checked it all - screws, metering height, low circuit clear, H circuit clear,new diaphragm/ and gaskits. Tested fuel and fuel filter, tank vent, pressure and vacuum engine and manifold. We did a few tests and found out it did draw air there.

I tried with grease and oil to block it, no change. Strange but proceeded to strip and rebuild carb carefully counterboring each seat for the o-rings. Found and modified washers the throttle shaft and L & H screws, adjusted the throttle shaft spring to increase its resistance one turn to compensate for friction.



No change.

hmmm... over I went with the checks in the carb. Tested the low circuit 3 times and then finally on the third test I noticed one of the idle drilling’s didn’t release any fluid! So hard to notice because the other two were spraying carb cleaner so violently it was hard to see each idle drilling clearly.
Couldn’t clear it. I was previously so a certsin it was clear, but clearly, I needed to look closer, and wear goggles at the same time to avoid carb cleaner in the eyes! After going back to Trains for advice on how to clear it I finally popped the Welch plug of and realised that when I removed the Welch plug the first time for the deep clean, I managed to perfectly tap a plug of metal into one of the Idle drilling’s as I passed the Welch plug and hit the carb itself yet didn’t notice it at the time!

(Bottom hole - notice it’s plugged and although looks superficial it’s half way down the idle drilling)


the only way I could get it out was drilling.

I went shopping for tiny tiny drill bits and a dremel drill station. Set it all up, found the right drill bit (0.5mm) and super carefully aligned the drill and gently touched the plug and it instantly released. I didn’t go all the way through, so even if 0.5mm wasn’t perfect it didn’t affect fuel flow.

so there we have it, 3 clean drilling’s once again.

a massive thank you to all of you who helped me on this project, especially to @trains this build wouldn’t be what it is if it wasn’t for his guidance and dedication to helping me throughout. I’d imagine we spent 10 hours plus of cumulative time talking about this saw on the phone and sharing of his advice as well as @pioneerguy600 for too giving me advice and guidance , I probably would have caught a ring on that chipped cylinder lining and destroyed it as well as all the other advice he has shared.





it was dark by the time I filmed the video, but you can hear the tune its alive and kicking and singing its beautiful 2 stroke song