McCulloch Chain Saws

[mad murdock]

. I have limited experience
with the 10 series saws. .




Lee

Whats this?!?! We cna fix that for you, I'll trade you straight up a couple 10-10's to play with, for one of your big cube macs:hmm3grin2orange: (Just askin'), seriously, you need to play with the 10-10's they are a fun saw, in any variety!

 

[minosi]

Should be 47865 for the standard bore. Same as the CP125 and MC101, buy two sets as I need some for my 101AA...Mark

I'll call Perry, if he has some I'll get you a set...

I agree that looking at the rings it appears to be a large ring end gap, vs. some kind of break or chip. Wonder if someone overbored then threw in stock bore rings?

As far as the fuel line goes, will the "line in a line" trick work...I did that to a *gasp* 750 I rebuilt.

Any thoughts on how to test how well the DSP valve is sealing?

Thanks for all the help on this saw guys!!!

Andy

 

[leeha]

minosi
If your refering to Perry at Karts & Parts in Canada
he is out of stock on the 47865 rings. But you can
use the 85608 rings which i believe are for the SP125C.
The 85608 is a cast ring for use on a chrome bore but
you can use cast rings on cast bores. Been done millions
of times. They just won't have quite the life expectancy
as the chrome rings. The 85608 rings are everywhere.
Very easy to find.



Lee

 

[mactodd]

minosi
If your refering to Perry at Karts & Parts in Canada
he is out of stock on the 47865 rings. But you can
use the 85608 rings which i believe are for the SP125C.
The 85608 is a cast ring for use on a chrome bore but
you can use cast rings on cast bores. Been done millions
of times. They just won't have quite the life expectancy
as the chrome rings. The 85608 rings are everywhere.
Very easy to find.



Lee

I'll certainly defer to your experiance, Lee, but bear with me here. All of the thin rings I have seen, regardless of the manufactuer ( Mac, Poulan, Kawasaki, Yamaha) were chrome spring steel. I can't imagine cast iron in the thin dimensions surviving very long. What am I missing here?

 

[leeha]

I'll certainly defer to your experiance, Lee, but bear with me here. All of the thin rings I have seen, regardless of the manufactuer ( Mac, Poulan, Kawasaki, Yamaha) were chrome spring steel. I can't imagine cast iron in the thin dimensions surviving very long. What am I missing here?

The 47865 rings used in cast iron bores has a chrome
face. The 85608 which is used in a chrome bore doe's
not have the chrome face. At least thats how it looks
to me. The old rule of thumb is you can't run a chrome
ring in a chrome bore. You can run a cast ring in chrome
or cast bores. Both rings can be run in Nickasil bores.



Lee

 

[leeha]

Just took a look in my Mac piston, ring book.
The 85608 ring is used in the SP125C chrome
bore block. But it is also used in the SP125
cast iron bore block and offered in over sizes.
85609 .010, 85610 .020, 85611 .030, This ring
could be a moly ring with out the chrome face
and thats why it can be used in both blocks.
But in any case using the 85608 in a 797 will not
have any issues.




Lee

 

[jerrycmorrow]

...you can't run a chrome
ring in a chrome bore...can be run in Nickasil bores.

that begs the question - why? only reason i can fathom is slow to no breakin but why wouldn't that be the same case with the nickasil?

 

[mactodd]

You can't run rings, pistons and cylinders with the same material, or they will literally weld themselves together. Chrome and Nikasil are dissimilar metals.
My original question to Lee was not about whether cast could be run in a chrome bore, but rather if the thin rings were actually cast iron. Reason being is CI is brittle, hence why they are mostly thicker so that they will last. The thin rings are usually some type of steel, and sometimes chromed or coated with some other hard material.

 

[minosi]

You all know "The Fire Breathing Beast" wasn't going to sit long without being touched....


Broken down on the bench, I'll skip the nitty-gritty...so much in common with the other saws.

View attachment 282050



Someones been in here!

View attachment 282051



I think I remember some debate on this a while back, this is a pic of exactly how the flywheel-side seals came out (separated for clarity, they were obviously together when installed)

View attachment 282052


More...

 

[minosi]

I figure a pictures worth a thousand words, here's how to remove the crankshaft from these fixed head saws...


First, a pic of the machined surface that only allows the crank to come out one way:

View attachment 282055



Push the piston to TDC, carefully rotate the crank to clear the rod, and gently pull the con-rod/piston assembly up and out of the reed/intake port:

View attachment 282056



Lightly tap on the clutch side of the crank with a rubber mallet, this will free the bearing and allow the crank to be removed:

View attachment 282061



Remove rod from port and pull your piston assembly up and out:

View attachment 282066



More...

 

[mad murdock]

Awesome photo log of disassembly! Looks pretty good in there, for the price you paid! Can't wait to hear it run

 

[minosi]

Thanks dude, me too!

 

[leeha]

Nice job minosi.
There one of my favorites.




Lee

 

[minosi]

Soooo, there's always something...


Reason for low compression becoming more obvious...this is the intake side:

View attachment 282067



After some "massaging", got the ring out...that mark under the damage is nothing but evidence something happened. Nothing I'm concerned with.

View attachment 282068



Exhaust side looks good, just some discoloration...scratches are insignificant.

View attachment 282070


Not sure how that area between the rings got damaged without damaging the rings or the rest of the piston...cylinder looks good.


Here is some engine news:

Bore: 2.304/305

Piston: 2.292


I going to rock on with the piston, a lite hone and new rings....sound OK?

 

[minosi]

One of those rings looks like the outer face is knocked off. Don't get crazy and try to get it running before you pull it down and look. If the other ring is bad, somewhere, that is probably most of you low compression problem.

ODW, A shout out is in order

-Andy

 

[heimannm]

I am going to guess something got past the AF, through the carburetor and reed valves into the piston and caused the damage you see.

Do let us know if you find a source for the rings, I will need some for my project as well.

Mark

Found the 85608 on e-bay for $19.99, free shipping. Got them...

 

[leeha]

Soooo, there's always something...


Reason for low compression becoming more obvious...this is the intake side:

View attachment 282067



After some "massaging", got the ring out...that mark under the damage is nothing but evidence something happened. Nothing I'm concerned with.

View attachment 282068



Exhaust side looks good, just some discoloration...scratches are insignificant.

View attachment 282070


Not sure how that area between the rings got damaged without damaging the rings or the rest of the piston...cylinder looks good.


Here is some good news:

Bore: 2.300

Piston: 2.28


I going to rock on with the piston, a lite hone and new rings....sound OK?

Those numbers don't match up.
That bore is .020 oversize. and the piston
i would guess is a very worn .010 over. A
standard piston is typically 2.275 diameter.
Might want to double check.



Lee

 

[minosi]

Those numbers don't match up.
That bore is .020 oversize. and the piston
i would guess is a very worn .010 over. A
standard piston is typically 2.275 diameter.
Might want to double check.Lee

Thanks Lee,

I'm going to my engine guy this morning to figure this out.

The calipers should be close if not right on, it's probably the bore I measured incorrectly...don't have a good tool to measure that.

-Andy

 

[minosi]

Lee & other Guru's:


Piston 2.292

Bore: 2.304/.305


Can I use this piston with new .020 rings?

Can I use .030 over rings and file the end gaps "to spec"?

Do I have to go .030 over?

-Andy

 

[OldDeadWood]

Bore

You need to talk this over with your engine guy and look in your wallet.

If the cylinder bore is not out of round and there isn't much taper in the bore you may get away with a new .020 over piston and rings. But if the bore is smaller at the bottom and wide at the top the rings will blow out in no time.

If the measurements by your engine guy are not good then you might as well bore to .030.

Have him double check all the measurements first.

ODW