McCulloch Chain Saws

[Walter Glover]

Would love to know exact differences of the A B and C pistons and cylinders for the SP80 saws. Was it diameters? Squish? If squish which piston is tallest?
My cylinder is unmarked
Needs repair or at minimum a hone and new piston

 

[heimannm]

The bore diameters and corresponding piston diameters were slightly different. You can see the details in the chart below.

According to the best information I have, unmarked cylinders were "B".

Mark

 

[Walter Glover]

Thank you for the chart
I cannot read any differences in the SP80 pistons cylinders sizes or part numbers. Be cool to get a piston that is 'tall' to allow customizing the squish. That dimension is absent

 

[heimannm]

You are correct on the SP80, only one piston/cylinder listed but the did change the PN on the rings; not sure how or why they did that.

All of the later 82 cc saws except the PM8200 used the "A", "B", "C" piston and cylinder designations.

Mark

 

[fossil]

Thank you for the chart
I cannot read any differences in the SP80 pistons cylinders sizes or part numbers. Be cool to get a piston that is 'tall' to allow customizing the squish. That dimension is absent

Walter,
The SP80 hs a chrome plated cylinder bore according to a manual supplement. I assume the saws with oversize pistons available have iron or steel liners that can be bored oversize. Mark would be able to tell us for sure.

 

[heimannm]

I believe these are true statements based on experience and the documentation that I have:

All of the 82 cc saws were chrome bore.

All of the -10 saws (1-10, 2-10, etc.) were cast iron liners except perhaps the very last of the 7-10A saws.

Early CP models (CP55 & CP70) were cast iron liners, later models were chrome plated.

All of the SP saws (SP60, SP70, SP80, 81, 82) were chrome plated.

All of the 57 cc saws were chrome bore (PM55, 555, 570, 10-10S).

All other Pro Mac or PM models (10 Series) were chrome plated.

Mark

 

[fossil]

Thanks Mark. Great info to have on hand.

 

[Walter Glover]

Any thoughts on installing a liner vs replating?

 

[fossil]

Any thoughts on installing a liner vs replating?

Lordy Walter. I thought about it for a minute and it hurt my brain.

 

[fossil]

You are correct on the SP80, only one piston/cylinder listed but the did change the PN on the rings; not sure how or why they did that.

Mark

Doing a little digging on the ring change on the SP80 and found this in that supplemental service guide for the SP80



I see the IPL lists two different sets so that may be the reason

 

[Walter Glover]

Might be a great project. Install a liner and make a piston to suit.

 

[heimannm]

There was an outfit called Northwest Sleeve in the town (I kid you not) Boring, Oregon. I don't know if they are still in business but a Google search shows their phone number as 503 666 8430. I never used them but I have heard from others that they were well equipped to repair/replace sleeves in motorcycles, kart engines, etc.

I would expect you could provide them with the cylinder to be repaired and a new piston ("A", "B", or "C" would not matter any here) or an original SP80 piston and they could match the sleeve to the piston.

Mark

 

[Walter Glover]

Melling makes a sleeve the correct i.d. for these saws and so plan to maybe do this myself. For piston will buy from Chainsawr and then backup plan is to cast my own and machine it to fit.
I think all these steps to a rebuild would be great skills to test out.

 

[heimannm]

Keep in mind that pistons are not simply cylindrical objects, there is both a taper (top is smaller I.D. than the bottom) and an oval shape through the diameter to account for differential heating while in operation. I don't want to discourage you, just pointing out some of the intricacies of piston design and manufacturing.

What ever you do, keep us all informed.

Mark

 

[Walter Glover]

Will do Mark
Ordered piston and pin bearings as first step.
WRT the Oval measure on one of these pistons I think the interrupted skirt makes that inconsequential.
The taper is easy to turn in a lathe and is only 1.5 thousands in the length of the piston
The liners are available with 0.125" wall. Thinking that would be reduced for this app to around 1/16" to fit whatever the boring came out to.
Holding the cylinder and cutting the ports are tricky I bet as well as getting the fit correct so the liner stays put.
I have emailed an outfit that replates cylinders so if possible will try that route first.
Want to see my sp80 run as it should haha.
Cheers

 

[rwoods]

Just guessing here, but it is probably cheaper to replate than sleeve unless you are equipped to do it yourself. Ron

 

[Walter Glover]

Ron i plan to get it replated as first option. Liner will be backup plan and yes would do it myself

 

[boda65]

Ok, I’ve never come here to gripe before but I guess I’m in a mood. Does anyone have any luck with EBay? Mostly I see $150 non running 1-41’s, $350 10-10’s, $45 air filters and such. Tonight this was listed and the guy said it runs great! I’m not sure how , that coil flopping around has to throw off the timing a little LOL. $86 plus shipping! A while back I sold a lot of two complete Power Mac 6’s shipped for less than that. Both saws and parts are usually listed at astronomical prices, I don’t have time to follow them all to see if they sell or not. Maybe I’m just becoming a grumpy old tightwad, I don’t know. Anyways, I am truly happy for those of you finding the truckloads of saws at what I assume are reasonable prices. It’s a fun hobby.

 

[emf123]

I received a package today, not quite McCulloch, but...

It looks an awful lot like a 1-10...

View attachment 621096

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Then again...

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This is a Danarm 55 that Captain Dangers arranged for me.

Mark

So Mark, what's the story with the Danarm????? I remember seeing one on ebay a while back, wondering how the heck did they get away with cloning a Mac. There's subtle differences, but it's like they completely copied it!!! Was there any agreement between the companies? Did they clone any other saws?

Eric

 

[RolandM]

I received a package today, not quite McCulloch, but...

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Very nicely packed for the long trip across the Atlantic.

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That is an odd color in the package.

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It looks an awful lot like a 1-10...

View attachment 621096

View attachment 621097

View attachment 621098

Then again...

View attachment 621099

This is a Danarm 55 that Captain Dangers arranged for me.

Mark

Hi Mark and all,

Been following your Mcculloch exploits over the last few years from here in the UK.

I have a number of Danarm's and Mcculloch's for my day to day firewood cutting, as they share the same bar mount.

The 55 is very similar to a Ten series but also quite different in fine detail, for example the cranks look similar, but the points cam is different.

The striking difference is the use of a removable cylinder head on the 55 MK 1 and 2 models. This I believe relates to the lack of experience then, and still today in the UK with the foundry process to produce the closed casting like the Mcculloch and of course practically every other small engine of this type.

The MK3. is fitted with an Italian Giardoni closed cylinder, and chrome plated rather than with a cast in cylinder liner. These run the best.

There are also a number of variations, left hand and right hand starters, a coil sprung AV professional model ( Danarm invention and patent ) and a number of paint schemes. My favourite to go 55 is a ported MK3, RH start, badged as a Frontier and painted bright orange!

There are very few parts, and even less info about the old Danarm company out there, but sprockets and such are same as Mcculloch. It would be very interesting to know if it was a cooperative copy, the Danarm 110 and 125 are also strikingly similar to Pioneer Models.

Roland.