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getting close to putting the engine back together on the SP70. these are basically clamshell engines, though no plastic is involved. this photo is not my saw, I clipped it from another post on this site. I think it's a Stihl but my question is, do I put red dirko HT around the bearings where I marked in blue on the McCulloch?
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getting close to putting the engine back together on the SP70. these are basically clamshell engines, though no plastic is involved. this photo is not my saw, I clipped it from another post on this site. I think it's a Stihl but my question is, do I put red dirko HT around the bearings where I marked in blue on the McCulloch?
View attachment 1015397
I will use a very thin smear of Yamabond 4 there.
 
when installing new rings in a used cylinder I always cross hatch the cylinder walls with a ball hone in order to deglaze the cylinder walls and give the new rings a chance to seat. I have done this on many nikasil plated cylinders (mostly dirt bikes) and a few with steel sleeves.

having done a lot of reading on ball honing hard chrome bores last night I see varying opinions. I believe the McCulloch cylinders to be hard chrome plated so would appreciate any information on this. if the answer is no, do not ball hone then how do you get the rings to seat?
 
when installing new rings in a used cylinder I always cross hatch the cylinder walls with a ball hone in order to deglaze the cylinder walls and give the new rings a chance to seat. I have done this on many nikasil plated cylinders (mostly dirt bikes) and a few with steel sleeves.

having done a lot of reading on ball honing hard chrome bores last night I see varying opinions. I believe the McCulloch cylinders to be hard chrome plated so would appreciate any information on this. if the answer is no, do not ball hone then how do you get the rings to seat?

Yeah nah put the hone away man. Scotch bright just scrub it up with brake clean or whatever. A real good scrub. Dirt bikes too. I just did piston in the RM probably 2 hours on it now. Scotch bright scrub get it running and let it warm up good but not fouling up plug good just a normal warm up and then run the heck out of it.

Best thing to seat rings is a big load on it. Give it death
 
Most rebuilds I have to do involve sanding off aluminum transfer and putting a scotch bright pad on it. Im not sure if it would need to be ball honed after all that.
I will tell you that I generally use the highest quality rings I can get and used cylinders take a while to seat with them ( 10 or so tanks run) , they seat whether honed or not is my experience.
 
Wonderfully nice work.

I apply a very thin film of Dirko to the seals. None necessary for the bearings unless the case surfaces show defects from a previously loose bearing.

No ball hone on the Mac chrome for me either. It flakes bad enough all by itself as many will attest. Scotch-Brite Red for a bit of cross-hatch, but go easy there as well if there are any indications of thin spots or weird wear at the intake and exhaust ports.

You should be very proud of your effort!
 
Drove by a local barn today and saw people loading a dumpster. Decided to stop in. Seems the family is cleaning out and will be auctioning off anything of value. I, of course, asked about chainsaws and was directed to this 10-10A. Right Hand start. Spins over and seems to have decent compression. Likely has been sitting for 10+ years. Also had a bow bar and some pretty used up chains.

20221207_143008.jpg20221207_143005.jpg

Is it worth anything? I might go to the auction if it is. Otherwise, I didn't see anything else that tickled me.
 
Hello, I recently started fixing up an old Pro Mac 10-10, and I noticed when I was replacing the fuel line that the paint inside the fuel tank was disintegrating, looked like it was being disolved chemically, like when you use paint remover on old finishes. I took the tank apart and cleaned it as best I could with a small brush and scotch brite pads, then blew it out with air. I replaced the fuel filter, etc,. rebuilt the carburetor and now it runs great, but I noticed the other day the the paint around the fuel fill is failing too. I'm wondering if the cause is ethanol in the gas? I had bought some non ethanol gas, but ran out of it a while back, and I think it got mixed up with some regular gas, so now I need to get some more, but it is getting harder to find around here.
Any other ideas about what can cause the paint to blister like this?
 
Many (most?) of the old tanks will have paint peeling off. I think it is a combination of the material selection for the tanks, the preparation for the paint, the paint itself, and 40 to 60 years of exposure to various fuels and the enviroment. The later models with the "Pro Mac" yellow seem to be even more susecptable, often coming of in great flakes. If you think the ethanol causes paint to peel, try using some as paint remover and I believe you will find it has little affect.

Mark
 
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