MCCULLOCH The official McCulloch thread

[Dream]

So ive been wondering this for awhile, and I'm sure some of you have probably thought in the same direction.
If one wanted to "hot rod" a 10 series Mac, would it be possible to take an approach that might solve two problems at once?
Problem 1.
Clamshell design that makes it difficult to decrease "squish" without machining the crank bearing pockets in the cylinder.
Problem 2.
Piston wrist pin bearings that wreck the cylinder if they fail.

I'm wondering if a piston with a single wrist pin bearing and a different rod could be used to get the compression "squish" to around .020".
I know, it would take some fairly precise machine work, but could the crank pin be bored out of the crank, thereby making it a 3 piece crank like most modern saws?
If a rod/piston combination could be sourced to do that, one could then port the saw to do whatever they wanted performance-wise. Higher torque/speed/"horsepower".
Im not saying they are in desperate need of that at all, I'm extremely impressed by how most of mine run and hold up to modern saws.
I'm just wondering if they could be improved upon, or would it be a waste of time and money for a marginal gain.

 

[Bigmac]

So ive been wondering this for awhile, and I'm sure some of you have probably thought in the same direction.
If one wanted to "hot rod" a 10 series Mac, would it be possible to take an approach that might solve two problems at once?
Problem 1.
Clamshell design that makes it difficult to decrease "squish" without machining the crank bearing pockets in the cylinder.
Problem 2.
Piston wrist pin bearings that wreck the cylinder if they fail.

I'm wondering if a piston with a single wrist pin bearing and a different rod could be used to get the compression "squish" to around .020".
I know, it would take some fairly precise machine work, but could the crank pin be bored out of the crank, thereby making it a 3 piece crank like most modern saws?
If a rod/piston combination could be sourced to do that, one could then port the saw to do whatever they wanted performance-wise. Higher torque/speed/"horsepower".
Im not saying they are in desperate need of that at all, I'm extremely impressed by how most of mine run and hold up to modern saws.
I'm just wondering if they could be improved upon, or would it be a waste of time and money for a marginal gain.

There are several options, a tall piston or longer rod will also lower the port timing. I have never touched a a rigid 10 series, could a standard 10-10 be sleeved up to 82cc? I think the needle bearing issue is from high hour saws, a taller standard bearing piston with a pop up could be interesting. We don’t have much issues with needle bearing failures with the 101’s unless it’s got some high hour on it or something was wrong. I think a standard style piston upgrade would be feasible money wise, but a ground up redo would take a lot of money

 

[Al Smith]

I've yet to figure why they used that style of bearings .One of the later 82 cc models used a ,what I call "normal " with a pressed together crank shaft /rod with the bearing in it .8200 perhaps ?
As far as souping one up not much you can do .Some exhaust port work,.Some timing advance ,maybe 3 degrees .My 6-10 has a carb made from two with a larger choke size than normal which probably works like a ram tube some what .It was just an experiment that worked out .I had that thing apart so many times it's a wonder I didn't wear out the screws .

 

[Bigmac]

I've yet to figure why they used that style of bearings .One of the later 82 cc models used a ,what I call "normal " with a pressed together crank shaft /rod with the bearing in it .8200 perhaps ?
As far as souping one up not much you can do .Some exhaust port work,.Some timing advance ,maybe 3 degrees .My 6-10 has a carb made from two with a larger choke size than normal which probably works like a ram tube some what .It was just an experiment that worked out .I had that thing apart so many times it's a wonder I didn't wear out the screws .

That piston needle bearing setup distributes the load
Better than a center bearing, the press fit and nothing more to retain the bearing is the only real issue. I understand the modern method, and prefer it. But I work on a lot of 2 stroke motor cycles and big bore quads, and it’s amazing how much wear the piston takes and piston pin can often seize, or almost seize in the piston, in mid hour use, the pin bearing and piston gets replaced usually in way less that 100 hours. The pressed pin in the 60’s and 70’s as you know was a staple of domestic performance v8’s production across the manufacturing bored. The fast that these have lasted for a long time is proof the design is good, I still prefer the modern method, for easy of use. A modern Honda 450 mx bike recommends a piston change in 20 hours.

 

[Al Smith]

I've never needled one myself but have had needled ones as they came .One 700 I found another piston some place to get it going as the bore didn't have any damage .I could have replaced the needle bearings but have no idea where to find them .That might explain me finding a third 700 I forgot all about owning .As absent minded as I've gotten I might have another 125 hiding some place .

 

[Steve]

I've never needled one myself but have had needled ones as they came .One 700 I found another piston some place to get it going as the bore didn't have any damage .I could have replaced the needle bearings but have no idea where to find them .That might explain me finding a third 700 I forgot all about owning .As absent minded as I've gotten I might have another 125 hiding some place .

Yard sale Al! I'll be going through your area third weekend in July!

 

[Al Smith]

I'm kind of attached to my horde of semi worthless junk . I'll just say summer before last I got a bunch of things running again .In addition to a hand full of chainsaws ,some complete rebuilds were blowers ,weed wackers ,concrete saws ,hedge clippers and one bull dozer . It's almost never a question of if I have a part but rather where in the world is it . Of course it isn't always machinery because you have appliances, computers plus a garden to attend to and that green stuff you never get done trimming up all proper like it should be in Better Homes and Gardens . It's like "Ground Hog Day " just starts over forever like a stuck record .

 

[Clint53]

Wednesday, I posted this on my FB page.



Then Thursday I got this from a very nice guy I've known for around 50 years.






The filter did its job.




I was surprised when I took off the FW cover.


I am now the proud owner of four 10-10S's.
I will try starting it today.
Thanks for looking.

 

[Steve]

I'm kind of attached to my horde of semi worthless junk . I'll just say summer before last I got a bunch of things running again .In addition to a hand full of chainsaws ,some complete rebuilds were blowers ,weed wackers ,concrete saws ,hedge clippers and one bull dozer . It's almost never a question of if I have a part but rather where in the world is it . Of course it isn't always machinery because you have appliances, computers plus a garden to attend to and that green stuff you never get done trimming up all proper like it should be in Better Homes and Gardens . It's like "Ground Hog Day " just starts over forever like a stuck record .

Very true Al. I finally after 5 years of having a NOS 10-10 block assembled it and put it in a saw frame. Took me all of two hours. Why the hell could I not take two hours out of 5 years to swap it? Always something else to do I guess.

 

[Steve]

Tuesday, I posted this on my FB page.

View attachment 328479

Then Thursday I got this from a very nice guy I've known for around 50 years.
View attachment 328480

View attachment 328481



The filter did its job.
View attachment 328483



I was surprised when I took off the FW cover.
View attachment 328482

I am now the proud owner of four 10-10S's.
I will try starting it today.
Thanks for looking.

Nice score! As bad as that filter is caked with dust the carb box isn't too bad. Always thought the filtration on these saws was more of a suggestion that a filter!

 

[Clint53]

Nice score! As bad as that filter is caked with dust the carb box isn't too bad. Always thought the filtration on these saws was more of a suggestion that a filter!

Thanks Steve
It did well.
Clint

 

[Al Smith]

Those flat filters are a shade better than nothing at all ..It explains why many have worn intake side pistons .It's a wonder they still run as good as they do .The 10 series does have thicker piston rings though which might explain it .One of those 700's gifted to me was found at a garbage transfer site .Stuck tighter than a bulls azz at fly time with the recoil missing .I gave it a douche of Kroil,Liquid Wrench for about a week and unstuck it .In spite of that it runs like a top or did the last time I used it . I did rebuild the carb and I had a recoil and that is all I did to it .

 

[RI Chevy]

Maybe fabricate a foam type filter around that skeloton filter?

 

[heimannm]

The wrist pin bearings in the McCulloch saws are very standard drawn cup needle bearings that are still readily available. At least some the 10's used a B76 but I don't know off the top of my head if they were the later/larger wrist pins or the earlier/smaller wrist pins.

On many of the saws (large frame, PM6, Mini Mac, etc.) the bearing on the exhaust side is a closed end due to the exhaust port being in the path of the wrist pin.

Mark

 

[Clint53]

Maybe fabricate a foam type filter around that skeloton filter?

Just needs to be cleaned after each use.

 

[Al Smith]

I kind of figured there were .I also figured some place you can find the needles uncaged used on the crankshaft end of the connecting rod .This is just a subject I've never so far have needed to do so I'm totally ignorant of it .

 

[heimannm]

Some of the needles are still around like the 85246 used on the large frame saws and 63225 used on many 10 Series. The long needles used on the 123 cc models are getting hard to find.

Mark

 

[Clint53]

It sucks. Low compression and bad crank seals.
But it was free. LOL

 

[Al Smith]

I had thought of that also if push comes to shove .If you had the length and diameter it might be possible to pry them out of a caged unit .It would take a great deal of research to determine which one .This I do know at least at one time the needles for Harley twins used on the fork and blade connecting rod assembles could be ordered in different sizes .Like I said as of yet I haven't done anything like that but you never really know what might lie on down the road .--after thought ,I did a Google using "loose needle bearings "and they seem to be available .So at least that could be an option .

 

[Tugg]

What is the fuel line size in these old macs, is it 1/4 inch. Do you folks still run 20:1 even with modern oils?