McCulloch Chain Saws

[PogoInTheWoods]

I find it hard to determine the end gap when the piston has locating pins.

Isn't it pretty much a relative number (to the piston diameter) between the ring ends regardless of a pin? Seems like any measurement would be the same -- pin or no pin. The possible variable would be consideration of whether the pin diameter actually subtracts from the gap number itself. It certainly doesn't protrude far enough to dramatically affect compression, and the bevel of the ring around the pin typically closes under the pin -- which is (usually) inserted at the top of the ring land for that allowance.

Should I just plan on crank seals also?

I would since you're there. I'd also judge the bearings more by how they feel than how they look. Should be nice and smooth.

 

[heimannm]

On thin ring models, the pin is normally centered in the groove and you do have to account for it when looking at the end gap. I don't have an effective way to accurately measure the diameter of the pin to know what kind of clearance to provide for the ring end gap. I have not had a problem so far just using thin rings as they come except when I put the BP-1 back together; I did have to increase the end gap a bit on that one. Go carefully if you file the ends on a thin ring, they change very quickly.

Mark

 

[2broke2ride]

Funny we where just discussing this huh mark?

 

[toofuss]

Ok, well, this changes things a bit. The second saw I got from Mark, the sp81E, was seized. I had planned on cherry picking a few parts from it for the sp81 that had weak compression. I decided to try freeing it up and much to my surprise, after a 30 min soak with some deep creap and a little wiggling, it's freed up and making good compression. I gave it a little shot of premix and it's trying to fire even on a very nasty plug. So it looks like I may have 2 good candidates for freshening up.

The bad part is it's just blowing rusty lube and gas out of the decomp port. So it needs a full teardown and inspection at minimum. So much for borrowing parts lol.

Sent from my SM-G930R4 using Tapatalk

 

[2stroke_shaman]

I dont even try good saws without seals , gaskets and a carb kit . Most bearings too. Cheap insurance .

 

[Beetlejuice]

I got to spend the afternoon with a legend in the mac world today. Drove up to a little town in north east Iowa and had the pleasure of Getting the grand tour from Mr Mark Hieman, aka hiemanm. We did some tinkering with my 250, scrounged some parts up for my 10-10s and put an oil tank gasket in my 700. I also managed to pry a couple sp80/81 parts saws from him to attempt putting 1 together. Sorry for the lack of pictures, but I was in a bit of sensory overload.

Sent from my SM-G930R4 using Tapatalk

I'm jealous.

 

[Willeywoodcutter]

Just wanted to let you guys know I think it must be the piston pins in the Lil red barn kit... I have two connecting rods and i can press them into both with my fingers yikes.
This saw has been a big learning expierence for me as I've never worked on this style piston assembly so hopefully I can buy a nos piston kit and it will be a tight fit at least now I know it should not be able to move at all. Lucky for me the cylinder isn't toasted..the piston is so soft it took the damage instead and the saw was only idling. So in looking for a piston and pin with rings if anyone knows where I can get one..thanks for all the help here maybe one day ill see this saw cut wood ha..like I said so far its been a lot of learning.

 

[2broke2ride]

Just wanted to let you guys know I think it must be the piston pins in the Lil red barn kit... I have two connecting rods and i can press them into both with my fingers yikes.
This saw has been a big learning expierence for me as I've never worked on this style piston assembly so hopefully I can buy a nos piston kit and it will be a tight fit at least now I know it should not be able to move at all. Lucky for me the cylinder isn't toasted..the piston is so soft it took the damage instead and the saw was only idling. So in looking for a piston and pin with rings if anyone knows where I can get one..thanks for all the help here maybe one day ill see this saw cut wood ha..like I said so far its been a lot of learning.

Just so you know, nos piston kit does not come with the wrist pin as far as I know.
It comes with rings and bearings. At least that's how the one for my 7-10 came.

 

[toofuss]

And the saga continues. Here we have two cylinder jugs. One from an sp81e, and the other from an sp81.
First from the sp81

Sent from my SM-G930R4 using Tapatalk

 

[toofuss]

And the 81e.
My question is why the difference in the transfers? Anyone seen something like this before?

Sent from my SM-G930R4 using Tapatalk

 

[2stroke_shaman]

Got a little done on the pipe install. Round pegs don't fit square holes adapters needed . Sandblast the coatings off pipes, tig , grind inside . Should work !

 

[heimannm]

81E looks normal, the 80 almost looks like someone removed the divider from the transfer.

Mark

 

[rwoods]

Believe I read somewhere sometime back that MAC added the divider as a performance enhancement. Ron

 

[toofuss]

81E looks normal, the 80 almost looks like someone removed the divider from the transfer.

Mark

I wonder if that's a good or bad thing. The e I think is going to clean up and run, may need new bearings in the entire bottom end. I'm seriously debating putting the 81 crank in the 81E. I don't know. The E is definitely the nicer saw of the 2. I would need to swap pistons between cranks. And there is a little aluminum transfer off the bottom edge of the exhaust port. That or put all new bearings in the E crank. From the wrist pin on down.

Sent from my SM-G930R4 using Tapatalk

 

[rwoods]

Sp81e

Check post 50 in the new stickie for ads and brochures. MAC claims the SP81E is 20% more powerful due to a divided transfer port. That would suggest that the SP80 and SP81 had a different cylinder than the SP81E. Ron

Here is the divider

Here is one with out

Ron

 

[toofuss]

That explains a lot. Thanks Ron

Sent from my SM-G930R4 using Tapatalk

 

[shawn022]

Hey guys. What am I looking at here? 250? I looked around at pics but don't really know my Macs.

 

[toofuss]

Could be a 250,300,550, several different models in that's front tank family. The model number stamped on the bottom of the case would tell the tale

Sent from my SM-G930R4 using Tapatalk

 

[heimannm]

1-51, 1-52, or 1-53; hope for the 52 or 53 as they are 87 cc and have bearings in the piston, the 1-51 is 80 cc and has no bearings. 1-52 should have a Tillotson HL carburetor, 1-53 would normally have the MAC.

Flip the saw over and look for the model number stamped in the bottom of the crank case. This particular saw is a 1-50, serial number 8700.



Mark

 

[shawn022]

Thank you.
I will try and check it out this weekend. If I do I will post my findings.