Stihl 038AV Super....carb, piston, and refinishing questions

[Jason280]

I recently picked up a Stihl 038AV Super, with plans on using it as a dedicated 20" saw. Its an older West German model, and I assume it was likely manufactured sometime in the early 80's. The saw cranked easily, despite sitting for a loooong time, and seemed to run well. I wasn't able to pull the muffler, but compression was 150psi...so I took a chance on the saw.

Got it home, and was finally able to get the muffler off...scoring on the exhaust side of the piston. Intake side was perfect, but I haven't actually checked the cylinder to see how it looks. I cleaned off the years of bar oil and gunk, but then had trouble getting it to crank again. Once I did, it idled poorly, and seemed to bog at WOT. I'm not sure if simply the filter was completely clogged, and now the carb needs to be adjusted, or if its something a little more involved. Either way, I've decided to make it a project to play around with over the next month or so.

I know the carb probably needs to be cleaned, but how are the Chinese clone carbs holding up? I know this is probably sacrilege on an old workhorse 038, but I have had great luck with these carbs on Stihl line trimmers...and they are damn near cheaper than rebuild kits!

As far as the scoring is concerned, I will likely be dropping in a replacement piston (at the very least). I've decided if I am going to this much trouble, might as well refinish the saw. I know a few people have been using Ford Gray, but how well does the paint hold up? Anyone tried powder coating?

Any advice/suggestions?

 

[Jason280]

Here are few pics before being cleaned up...

 

[BuckthornBonnie]

Bing carb? Clean and kit it is my first suggestion. Some AM carbs are problematic.
Plenty on here have powdercoated saws, yes. I’d split the case if you’re going to that depth in the rebuild.
It probably needs the usual fixes (rubber components, pressure/vacuum test) and a good cleaning.

 

[TRTermite]

Are you bating us? You have been a member since 2007 and you are asking questions Like I would. I have a 044 and was surprised how great the cylinder cleaned up with my dremel and also surprised at the effort it took. It took 3 times for a statement a friend made to sink in "Those cylinders usually clean up" So I worked a little harder and realized I was feeling Aluminum transfer ridges not scoring grooves... I'll be lurking in the back ground while you dinker
Nice saw for a project

 

[Jason280]

I haven't had time to get much further with the saw, just cleaned it up a bit...

 

[Sam R]

I'd definitely p/v test it. The piston scored for a reason; especially on the exhaust side only - it's telling you something. If you cleaned it up and then it started to run poorly; could be the carb was tuned to run with a rotten dirty air filter, which would make it run lean with a clean filter. I've seen saws like that have a leak in the crankcase seam. Righteous saws from what I understand; but expensive in this day & age if you want to use OEM parts.

 

[Jason280]

I'll pressure test the crankcase and tank, just to make sure.

What's the general consensus on Lil Red Barn pistons?

 

[rodeobob]

...scoring on the exhaust side of the piston. Intake side was perfect, but I haven't actually checked the cylinder to see how it looks. I cleaned off the years of bar oil and gunk, but then had trouble getting it to crank again. Once I did, it idled poorly, and seemed to bog at WOT.

Heres a tip.
If its scored treat it like its dead. Do not start it, stuff like that can never magically fix itself. All that will ever happen will be it getting worse.
Strip it down and have a proper look. If youre lucky there will be a bit of transfer to clean off the cyl and with just a new piston you are good to go. If you are not lucky your little WOT drama was it running lean and youve now got to put a cylinder on it as well.

Cheers.