Porting a saw

[hamradio]

Hi,
I've never ported an engine before. I'm going to be rebuilding my 039, again, since the bearings went out. I found some cheap NOS bearings on eBay, and I'll pick up new oil seals, but, I figure, as long as I've got it apart, I might as well port the cylinder. Any tips? I've been practicing on a couple weed eaters I've got around, and the one I finished, that is my homemade clearing saw, really has a nice powerband at the top end of the RPMs. I've got my junk Mcculloch on the bench, and the dremel is out, and I've gone to work on the cylinder. I know a bit about engines; I've had all my saws completely torn down a couple times (039, 011AV, Olympyk 935DF), and have rebuilt a 1985 Kawasaki 185 ATV. Some people say 2 strokes are harder to work on, but I feel that they are easier, since you don't need new head gaskets; permatex works most of the time. But, like I said, any tips on porting?

 

[ftm]

Got a flow bench? I think the consensus was it shouldn't be done at home. If you feel like cleaning up the casting that is fine but to see any real results you need the proper tools and experience. Otherwise you may do more harm than good.

 

[Mr.]

Make it look stock. Keep everything between 1 and 2 mm from stock and leave the transfers alone for now. Do not go too far and chamfer the ports.

Fred

BTW use factory gaskets in the 39 or you can end up with some bottom end probs.

 

[timberwolf]

Take the exhaust out wider to about 1 mm from the skirt edge or about 65% of the bore, and maybe take the intake down 1 mm or so. I would not raise the exhaust on an 039, no point to try to make a screamer out of it, keep the torque instead, esp if it is just for cutting firewood.

 

[hamradio]

I use the saw, mainly for woodcutting. I've probably run 5 cords through it. One long day of cutting in an area where a friend wanted to clear, and just went nuts dropping trees with his 044 and MS210, and leaving everything for others to cut up, and make huge brush piles from. I went to cut wood, a few days later, and probably got 1/4 cord cut, when the saw moved in my hands, and ran sluggishly for a few seconds. I had ear protectors on, so I couldn't hear it, but I shut it off, and something didn't seem right. I put the ear protectors around my neck, and slowly pulled the saw over, and it was making a noise, like bad bearings. I only paid $25 for the engine in it; I bought the saw for $100 on eBay, for parts, and called up my local STIHL dealer, asking if they had any 039 parts saws. The one I got had been used a bit, and was missing the top handle, oiler, side cover, and some other parts, but had a good engine, with very light scoring in the cylinder. Good enough for me. My cylinder was scored terribly that came on my saw. It looked as if someone had run it without 2 stroke oil, with there being 2 stroke oil in the bar oil tank. Other than that, it was a brand new saw. What I've cut with it, is probably more cutting than it ever did, total, before I owned it. One thing I did notice, was that the cylinder base gaskets on 039's appear to be permatex. I used permatex again on it. Should I have done this?

Also, the bearings needed replacing when I rebuilt it, but I didn't have the money to get new bearings. I think I'll tear the saw down tonight, and check out what happened in the bottom end.

Also, could I do any modifications to this, to make it perform like a stock 044? An 044 seems heavier, but, the engine really isn't that much bigger. Any K&N style filters available for an 039? I thought, after I bought the 039, that I wouldn't want a larger saw, but I'm looking into an 044 or 046 parts saw, now. The STIHL dealer that I got my second 039 parts saw from even threw in a starter, but it is for an 044.

 

[fishhuntcutwood]

Also, could I do any modifications to this, to make it perform like a stock 044? An 044 seems heavier, but, the engine really isn't that much bigger.

That's a stretch. Opening the muffler will help, but the 039 and 044 really aren't comparable saws. The 044 weighs a pound more, but the increase in hp, torque, powerband, professional features and so on more than makes up for it. And you really can't go off of the engines dimensions when considering weight. There's saw with magnesium cases, and some with polymer cases and displacement has no relation to weight either.

Jeff