Stihl 038 Magnum II - Slight Rebuild

[Cloudfeather]

Picked up a Mag II from my friend's uncle yesterday. "It was a hell of a saw until I dropped a tree on it...". Other than the missing handle and being caked in age old sawdust, she looked really good. $100 bucks for her. Sold!

So, the fun begins. It had no handle/tank and had a box full of screws and random bits, but everything was there. I ordered a new shroud, tank, manifold, and muffler for it. Another hundred for all that(aftermarket parts).

This was what she looked like when I brought her in yesterday. Today I tore her down, replaced the oil pump gasket, cleaned up the P&C(slight porting) and just gave her a good scrubbing. She's a bit rough paint wise, but in really good shape. I'll post some more pics later and as I start putting her back together.

 

[rocketnorton]

i have 038 stuff if ya need somethin. coulda helped w/tank. oe.

 

[grizz55chev]

Worthy saw, good price.

 

[bulletpruf]

In for updates. I'm going through an 038 Magnum.

 

[Cloudfeather]

i have 038 stuff if ya need somethin. coulda helped w/tank. oe.

I'll keep that in mind if either of mine need a replacement tank in the future. Thank you.

The hardest part of this will be waiting for parts to get here. lol

 

[Cloudfeather]

Ok, I'm still waiting on the tank and shroud to come in, but almost all the other parts are in. Cylinder cleaned up and slightly ported, muffler modded, solder coming in tomorrow so I can commence squish testing, etc.
I sand blasted the muffler and repainted with VHT paint and will bake it tomorrow to cure. Hopefully have more pics this weekend, just been really busy.

Here's a silly question. Does anyone know if they make the flip style caps or any kind of conversion to go to the flip style caps?

 

[rocketnorton]

there is conversion the other way, flippy to non... gotta ask why youd want flippys? just curious, don't dislike em.

I also have oe shroud.

 

[Cloudfeather]

I'm just tired of having to use the screwdriver end of my saw tool to open the caps. No other reason. Just for convenience.

 

[Cloudfeather]

So, I've been trying to measure the squish on this cylinder. I'm using model clay and it works really well. It's currently sitting at about .050. Just to see what it did, I removed the base gasket and it's at about .030, but there is a slight issue.

With the base gasket gone, even though the squish is at about .030, you can feel the piston "bottoming out" slightly at TDC. When you look inside the cylinder, all the way at the top, there is a very slight ridge around the circumference. Only about a half a millimeter thick. Any ideas as to what that is or if I'm doing something wrong? Thanks.

 

[Garth elder]

May just be the lip that forms at the top of the cylinder assuming the machine has seen a bit of work

 

[rocketnorton]

carbon above rings?

 

[Cloudfeather]

Ok, so the pieces have been coming in slowly but steadily. The original tank I ordered is MIA somewhere but I found on right over in PA that was on sale for half price and it comes with the flip style cap, so that's a bonus. Here's where she stands right now.

New head gasket was a thinner material, I don't think I'm going to mess with the squish any further unless I have compression issues. Got the muffler opened up a bit, painted with VHT paint and baked. Elasto-start handle(I know, they're for sissies), and I upgraded the dogs. Seeing as how this will be dedicated to felling and bucking, I figured I might as well go big or go home. Tank should be in tomorrow and the OE style shroud and name tag should be here in the next few days as well.

I also managed to snag up a full wrap handle from a guy on youtube, so I'm pretty excited about that as well. Really good shape, just painted it with some truck bed liner.

 

[Cloudfeather]

OK, I thought I had an air leak, but (me being really stupid), I forgot to re-tighten the cylinder bolts when I put the handle/tank on. After a few pulls, she fired up nice. Didn't get a chance to tune the carb, but she sounds like she's got a lot of promise. This is where she sits right now. Just need to put on the new shroud. Super excited.

 

[louie69]

As a fire wood cutter every winter her in ozz my 038 magnum has never let me down i bort it new when they first came out never been rebuilt just used every winter i wood cut about 15 to 16 ton then have another 3 ton to left over each winter in case its to wet to go out. 2016 was our wettest winter for 15 to 20 years i was glad to see it over.Use to have a stihl dealer here in my town know its changed over to husquvarna so looks like if i want to by a new stihl i have to drive 100 km to be able to by one which sucks.

 

[Chashowlett]

I got rid of my .63 mm base gasket and it definitely added some snap. Also added this- see pics. They were on 73cc Dolmar/Makita , the shorter one mounted on the side the longer one went through the chamber like I did mine. Works awesome Btw!

 

[bulletpruf]

What did you do to your muffler? You mention that you modded it; curious to hear what route you took.

Same with the porting -- did you just port match the exhaust?

Thanks

Scott

 

[Chashowlett]

Didn't have to touch the muffler, it was wide open. No, I just got rid of the thick-ass base gasket. And deburred the piston, blended the transfers, the exhaust was really tidy, just gasket matching and a little blending at the knife edge. I did hone the cylinder about a tenth, it was out of round a tad. Cleaning up the piston took off about a gram. That helped the throttle response. Has anyone ever tried gas porting the piston or Total Seal rings? Just wondering. Is this the right bore for Mag II? And serial number starts with 1

 

[bulletpruf]

Thanks for the details; now I have more questions!

Can you explain "honed a tenth"? As in .1? Because that sure does sound like a lot of material to remove. Maybe you removed a hundredth or a thousandth?

How did you find out that it was out of round? Dial bore gauge?

Also curious to hear more about how you deburred the piston -- where and how did you remove some material?

Scott

 

[Chashowlett]

Tenth of a thou

 

[Chashowlett]

The holes by the wrist pin have casting flaws and are a choke point ..venturi shape the in and out. Practice on a old piston first. Weigh before and after. I'll do a old piston and show a picture. I didn't take any pictures of this saw's piston or any others for that matter...its a racing trick and some people get butt hurt sharing racing secrets. You probably should pm me. Don't want to rustle any feathers. I have a killer trick for a MS200T . I just finished one and O-boy, even I'm impressed and I've crewed for a 6000 hp car.