McCulloch Power Mac 6 Advice Needed

[DarkOverCast]

So while stopping in to buy some chainsaw parts for one I was working on for a friend I ended up walking out with two complete power Macs.

They're both later variants with the auto oiler, one has a chain brake.

Both have low compression and would randomly lock up.

The first one without the chain brake was the cleanest. I've been in the market for an all metal one hander and judging from what I've read these are supposed to be tough little saws...

I tore this saw down today, the upper piston ring was stuck, it took alot of effort to get it free, this saw has been sitting on a shelf for 10-15+ years.

I figured while I have it torn down this far I mine as well slap a NOS piston and ring set in it right?

One question I had was on this chrome lined bore is it unadvisable to hone it? I never get crazy with a hone, just enough to add back crosshatch to set the new rings.

Searched everywhere and couldn't find a NOS jug...

Also I figured while it's torn down why not port it too? I've never done this before but get the jist of it, go wider but not taller or shorter or you'll change the timing, and polish it really well.

This saw has a bridge right in the middle of the exhaust port that seems rather restrictive.

Also how do I seperate the piston from the rod?? I really can't tell how it comes apart.

I'm usually a homelite guy but couldn't pass up on this clean yeller saw and the parts saw to go with it.

My recoil starter drum is also cracking, I read somewhere you can install a speedi sleeve over it to help strengthen it up? That would be cool as the only NOS ones I found were also cracked.


All boxed up and labeled so I don't forget

Does this cylinder look okay?


Bridge I'd like to remove when I port it.

And this is the other saw

 

[pioneerguy600]

Don`t remove the bridge in the exhaust port or the rings will pop out into the port and hang up, busted piston is the result.

 

[DarkOverCast]

Don`t remove the bridge in the exhaust port or the rings will pop out into the port and hang up, busted piston is the result.

I'm curious as to why the intake doesn't have a bridge as well if that's the case?

 

[lostone]

I cannot remember but I believe the piston doesn't have a ring retaining pin on these so the rings can spin around on the piston, the exhaust port bridge is there to keep enough curve on the ring so it cannot jump out into the port and clip a ring. I have several of these saws but it's been better than 10 years since I worked on them so I could be wrong on the PM6 about the pin but I'm pretty sure it didn't have one.

 

[DarkOverCast]

You are absolutely correct, there's no pin for the rings.

Well thanks, I learned something today. I'll just polish/widen those two ports and call it a day.

I did measure the gap on the old rings that were stuck. They were at 13 thousands so mine as well replace them like I thought.

 

[pioneerguy600]

I'm curious as to why the intake doesn't have a bridge as well if that's the case?

Width of the port. If the port is too wide the same would happen.

 

[canadian175]

Keep us posted on how you are making out. I have a couple my self and may temp it some day in near future.

 

[heimannm]

I should have all of the parts you would need to rebuild it, including a NOS cylinder if you want to go that far.

The wrist pin presses out, it is a press fit in the rod and there are no other clips to secure it.

It is not a good idea to hone a chrome bore, you can do your best to clean off any carbon accumulations with some emery cloth or scotch brite pads.

There are several threads dealing with McCulloch chainsaws including the small saws like the PM6 models. Investigate the search function (upper RH corner) and see how much you can uncover as there is a lot of information out there. Google searches will often find what you are looking for here on Arboristsite.

Mark

 

[canadian175]

I should have all of the parts you would need to rebuild it, including a NOS cylinder if you want to go that far.

The wrist pin presses out, it is a press fit in the rod and there are no other clips to secure it.

It is not a good idea to hone a chrome bore, you can do your best to clean off any carbon accumulations with some emery cloth or scotch brite pads.

There are several threads dealing with McCulloch chainsaws including the small saws like the PM6 models. Investigate the search function (upper RH corner) and see how much you can uncover as there is a lot of information out there. Google searches will often find what you are looking for here on Arboristsite.

Mark

View attachment 1005786

Nice little choppers.love those little guys.