Commencing the odyssey of fixing up some Stihls

My boys and I went out to the shop tonight for a bit. We quickly figured out we need to pick up some T-handled Torx drivers. My socket set is too big to fit in the muffler screw holes on both the 192tc's and the 362's.

Here are the compression results

192 w/12" bar and chain


192tc with 14" bar, no chain



The 362 powerhead only



362 with 20" B&C (the one that ran yesterday)



Here's the kicker. Both spark plugs were loose on the 362's. The one with the highest compression has stripped threads but I was able to catch a good one and get a decent seal on the tester.

The one with the lowest is the one that started yesterday! This was with a loose plug and half stripped threads. I honestly can't believe it started.



Depending on condition of the cylinder on the high compression 362, I might have my FIL TIG up the edges, then I'll fire up the Bridgeport and chuck up the boring head and rethread. If the cylinder is bad, We might try one of the Chinese Huztl top end kits on both. I can always put a Meteor if the cheapo doesn't work.

We want to pull the mufflers on all of them to take a peek inside. As I said, I need to get some longer Torx drivers. Also, rings, piston and wrist pin bearings might be in order for all. There's misc. hardware missing as well.

I'll keep this thread updated as we go.

 

Looking forward to the updates

T2 Tappin'

 

Well you have a good start and looks like you know what your dealing with. When your FIL does the tig weld on that cylinder shoot us a pic.

 

I'm not 100% sure I'll have him TIG it up. Part of it is cylinder condition. The other part is the fact that, while he's a perfectionist and excellent welder, he does things on his own timeline. And that's with paying jobs! No telling how long he would take on a freebie. The only leverage I have with him is if he needs to use my machining equipment, then I can get something done pretty quick.

I've got a few lots with 1" accumulation triggers to plow this morning, so I'll grab some tools (Torx) while I'm out and hopefully we'll get a peek inside today. Unless the lake effect machine kicks in, then it might be a while.

 

If the cylinders look good the top three have enough compression to run.

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I've never messed with a small saw like the 192. So far, from what I've found, 120-125 is pretty much what a new saw puts out.

 

Cracked into the low compression (80psi) 362 tonight. I have a few questions for those who are experts.

First off, the air filters were packed with saw dust. I wish I had taken a pic, but these will give you an idea.






Here's the cylinder and piston. It looks to be polished on the intake side.




Measured with a feeler gauge, ring end gap on the top ring was a tight .024, the bottom ring was .016.





Piston looks good on the sides, top has a little carbon.

Exhaust side:


Intake side:


Top:



Crank looks to have gotten hot, but is tight and smooth. Wrist pin seems good too.


My thoughts are to scuff the cylinder with some emory cloth and put new rings in. I think I'm going to try "Save a Thread" for the plug since my father in law is dealing with some issues. I'll replace the intake rubber, fuel and impluse line. Might open up the baffles inside the muffler too. Of course everything is going to get a good cleaning. With the damaged threads I couldn't really do a leak down test. It's something that will be done after I fix the plug hole.

Is there anything else I should be looking for while I have the jug off? Does anybody know the correct ring gap? Am I going down the wrong hole with scuffing the cylinder?

Thanks!

 

If you scuff the cylinder use a fine grade of emery and remember your working with plating. like 320 to 400 grit. I do not know what the ring gap is but I would replace the crank seals also.

Yep if the save thread does not work you can always get it welded later. It is nice to have options. The piston and cylinder does not look bad to me and would suspect just like you do that the rings are the culprit. Good luck and let us know how it turns out.

 

Try Muratic acid in that jug. Cleans em right up without taking the plating off.

 

This is true if you are trying to remove aluminum transfer from the piston due to scoring but I do not see that on this cylinder and the piston shows no signs of scoring. I think he just wants to scuff the cylinder a little so that new rings will seat ok.

 

Yep, there is no sign of seizure or aluminum transfer. The cylinder has a polished look on both exhaust and intake, but more so in the intake. This thing was sucking in saw dust for a while.

 

There are differing opinions on scuffing the cylinders on chainsaws but I have used ball hones on them before with no issues at all.

 

I probably would not replace the intake boot. I'd look at the fuel and impulse line and if they look good i would reuse them. A 362 is a pretty new saw and the rubber components should be in good shape. You are probably looking at $30-40 maybe more to replace these parts. I'd clean the cylinder up and put a new Stihl piston in it. Then vac and pressure test the saw. I'd also remove the fuel line and vacuum test it.If all is good I'd run it. Put a new fuel filter in it. The saw may need a carb kit depending on how long it has been sitting. If you need carb kits for these saws check with carb tech solutions. Their kits are $3 were the dealer is $10-12. You can also get fuel filters for $1.

 

Just curious, why replace the piston? There is no scoring and no sign of seizing.

I will do a leak down test after I can get good sealing on the saw. I'll test the fuel line too. Impulse looks to a direct port on the carb. I'll look at the intake, but I know these saws were run on ethanol gas so I figured while I have it apart it might be easier to swap parts now.
Several years ago, before I had my 361 I borrowed my brother's 026 Pro. It only had 10-15 hrs on it and I had to replace the crank seals. Ethanol is the Devil. Crank seals may happen regardless, but at this point I want to see if they are holding pressure. Again, the sparkplug hole is almost completely stripped. I barely caught enough thread for a seal on the compression tester. I only have the clutch cover and recoil removed at the moment. Flywheel and clutch are still in place.

Carb needs an exterior hosing (ie: cleaning) for sure, but believe it or not, this saw was running on Tuesday when I picked it and the others up.

 

I saw a Rotax tech down at Sun-n-Fun use fine grit Emory cloth on a 10 hr 582 in the mid 90's. Their carb boots were cracked, the cylinder sucked air and had a seizure resulting in an off field landing by a light aircraft magazine editor. Thankfully he shut it down quick and performed a perfect dead stick into a cow pasture. We noticed the cracks, pulled the motor and took it to the Rotax booth where they had the tools and parts to do a quick fix.

Here is the exact plane, my red Short bed was in the background.



Maybe the tech used it because that's all he had, but the engine was still under warranty so it must be an acceptable alternative. We flew that thing out of the pasture later that day.

 

I was thinking it had low compression but I forgot about the messed up threads on the spark plug hole. That is probably why they quit running it.

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Does a Rotax use nikasil plated cylinders. That is why some people do not like honing chainsaw cylinders. They are either chrome plated or nikasil plated.

 

I believe that it's more of the hone eroding the ports than going through the plating. Mastermind has a good video on his youtube channel on how he does it.