McCulloch Mini and Small CC Chainsaw's

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I just KNEW I shouldn't have looked at this thread.......

Back in 2007 I unearthed a little yellow machine partially disassembled in a shed, a Mac 110. All the parts were nearby and the compression was good. When I got it running the centrifugal clutch was not gripping. A new clutch was bought but after doing a few cuts the saw wouldn't run properly so I tore it apart, fixed what I could but it still ran poorly. Pulled it apart again, found it did need further work (can't remember what) and it's been in a box ever since.

Now, thanks to knowing there's a vast amount of info here maybe one day I'll take another look in the box.

I spend a disproportionate amount of time working on my small Mac saws. They are a P.I.T.A to work on, quirky, and can drive you nuts. But for some reason, addictive.
 
Assembled the saw and got it running for a few seconds several times by pouring fuel into the carb intake, but seems it won't suck fuel from the tank.

Certainly has a great sound, a real bark - much louder than expected for such a little motor.

Now I know it is mechanically OK it will be left alone, sooner or later someone else will want it. I have enough more modern working saws at the moment.
 
I spend a disproportionate amount of time working on my small Mac saws. They are a P.I.T.A to work on, quirky, and can drive you nuts. But for some reason, addictive.

Most people would probably whip it into the great unknown after the 5th time they took it apart and it didn't work.
But not us! We endure so much for these little saws, a true labor of love... Or maybe it's just spite, because after the 15th disassembly it's personal!

The up side is: after the umpteenth time of taking the same saw apart, for whatever problem shows up next... you get the special power of being able to disassemble and reassemble any mini mac in 4-5 minutes or less.

So much time, so much frustration... but the sound they make when they do run makes it all worth it.

God... we're weird.
 
Most people would probably whip it into the great unknown after the 5th time they took it apart and it didn't work.
But not us! We endure so much for these little saws, a true labor of love... Or maybe it's just spite, because after the 15th disassembly it's personal!

The up side is: after the umpteenth time of taking the same saw apart, for whatever problem shows up next... you get the special power of being able to disassemble and reassemble any mini mac in 4-5 minutes or less.

So much time, so much frustration... but the sound they make when they do run makes it all worth it.

God... we're weird.
I think i could remove a Mini Mac engine from the case blindfolded, haha!

Seriously once you get the hang of it, it's pretty easy. The throttle linkage is probably the trickiest part.
 
Assembled the saw and got it running for a few seconds several times by pouring fuel into the carb intake, but seems it won't suck fuel from the tank.

Certainly has a great sound, a real bark - much louder than expected for such a little motor.

Now I know it is mechanically OK it will be left alone, sooner or later someone else will want it. I have enough more modern working saws at the moment.
Couple things to check would be the carb diaphragm and inlet needle and metering lever. Make sure the vacuum pulse passage is not plugged. Also, I've heard the felt filter in the outlet of the fuel tank are known to get a hard "crust" on them from varnish that can prevent fuel from flowing. You might want to pull the tank and check it.
 
The throttle linkage is probably the trickiest part.
Rotate the flywheel so the magnets are at the top to hold it in place (and out of the way) for disassembly and reassembly..., and so ya don't forget where ya put it.
 
I think i could remove a Mini Mac engine from the case blindfolded, haha!

Seriously once you get the hang of it, it's pretty easy. The throttle linkage is probably the trickiest part.

Yeah, once you get into the rhythm it is really easy. I think most people are genuinely afraid to mess with these saws, they aren't really that bad though.

I never had a problem with the linkage, that was the easiest, it always fell into place. Removing the tank however, that was always the hang up. Blasted things would never let go.
 
Yeah, once you get into the rhythm it is really easy. I think most people are genuinely afraid to mess with these saws, they aren't really that bad though.

I never had a problem with the linkage, that was the easiest, it always fell into place. Removing the tank however, that was always the hang up. Blasted things would never let go.
Yeah I've had the fuel fitting stick a few times and fight to come apart, it's such an odd design. Personally I'd say the oiling system leaves the most to be desired, with that ridiculous rubber "T" and ends that just slip into the tank, pump and bar mount. You couldn't design something more prone to leaking oil if you wanted to. Someone said wrapping the ends in teflon tape helps them not leak, I'm planning on trying that.
 
Assembled the saw and got it running for a few seconds several times by pouring fuel into the carb intake, but seems it won't suck fuel from the tank.

Certainly has a great sound, a real bark - much louder than expected for such a little motor.

Now I know it is mechanically OK it will be left alone, sooner or later someone else will want it. I have enough more modern working saws at the moment.
I would try replacing the fuel line first. I've had similar problems and found a very small crack in my fuel line.

Sent from my SM-S367VL using Tapatalk
 
Yeah, once you get into the rhythm it is really easy. I think most people are genuinely afraid to mess with these saws, they aren't really that bad though.

I never had a problem with the linkage, that was the easiest, it always fell into place. Removing the tank however, that was always the hang up. Blasted things would never let go.
I hate removing and attaching the throttle linkage to the trigger too. I swear that clip is going to break one of these times. I keep thinking there must be a better way than using a needle nose pliers.

No problems with the tank. I take a screwdriver and pry/twist at the bottom mounting hole tab and it pops right out.

Sent from my SM-S367VL using Tapatalk
 
Not too sure if this is being posted in the right place but here is the question. I have four mac-110's and only the one with the least wear has a clutch that doesn't rattle when idling. All the clutch drums are a loose wobbly fit and the clutch shoes as well as the spiders are loose and wobbly. Does any one have a fix for the rattle without spending more money than the saw is worth?
 
Not too sure if this is being posted in the right place but here is the question. I have four mac-110's and only the one with the least wear has a clutch that doesn't rattle when idling. All the clutch drums are a loose wobbly fit and the clutch shoes as well as the spiders are loose and wobbly. Does any one have a fix for the rattle without spending more money than the saw is worth?

For what it's worth, I think most of mine are like that... it doesn't seem to affect the way they operate so I just run them. You could try replacing the clutch bearing.
 
So, I'm taking apart an MDC and I'm looking at the check valve. Of course it's stiff and dissolving in my hands. But as I’m looking at it, I get to wondering about how long these valves last, their durability and wonder if anyone has swapped the supplied valve from a kit with one of their own.

I know others have made check valves out of the black rubberized diaphragm material, and it has decent resistance to wear and ethanol fuel. But... then you have those tan teflon diaphragms that are incredibly resistant and durable to ethanol fuel and wear.
The OEM valve is about 7/32 and about .009 thick. Most diaphragms are about .006 - .009, which I imagine as long as they're within that range, I doubt it'll make any major performance difference. It’s just a one way valve, either it’s open or it’s closed, as long as it operates correctly... good.

The main thing I'm going for is durability. And the question came to mind as to why not make a check valve out of a material that was just as flexible as the nitrile rubberized material, but more resistant to ethanol fuel in the long run than that material is?
Then I start looking at the now butchered brass seat, that just refused to go peacefully, and obviously I realize I need to replace it.
What better time to experiment than now?

Now the valve kit mcculloch had for the MDC, was the same as the stand-alone walbro 86-523 seat kit that fits the *SDC, with maybe an exception for the welch plug. (can’t recall at the moment)
I mentioned this earlier about the supplied valve in the walbro kit, and questioned the long-term durability of it.
Now personally, I’ve always thought it was a formulation problem with the older valves themselves. You could argue that the material is much better now, and I’d agree with you. But the question remains of “upgrading” the stock material to another one, just as an experiment in durability and performance.

I not seeing any ill effects of this experiment. After looking into it, someone else passed the idea to make a valve with teflon, but from what I could tell, it doesn't seem like anyone really tried it out. If anyone has, let me know how it worked out.

So... does this sound interesting?

*and other carbs too.
 
So, I'm taking apart an MDC and I'm looking at the check valve. Of course it's stiff and dissolving in my hands. But as I’m looking at it, I get to wondering about how long these valves last, their durability and wonder if anyone has swapped the supplied valve from a kit with one of their own.

I know others have made check valves out of the black rubberized diaphragm material, and it has decent resistance to wear and ethanol fuel. But... then you have those tan teflon diaphragms that are incredibly resistant and durable to ethanol fuel and wear.
The OEM valve is about 7/32 and about .009 thick. Most diaphragms are about .006 - .009, which I imagine as long as they're within that range, I doubt it'll make any major performance difference. It’s just a one way valve, either it’s open or it’s closed, as long as it operates correctly... good.

The main thing I'm going for is durability. And the question came to mind as to why not make a check valve out of a material that was just as flexible as the nitrile rubberized material, but more resistant to ethanol fuel in the long run than that material is?
Then I start looking at the now butchered brass seat, that just refused to go peacefully, and obviously I realize I need to replace it.
What better time to experiment than now?

Now the valve kit mcculloch had for the MDC, was the same as the stand-alone walbro 86-523 seat kit that fits the *SDC, with maybe an exception for the welch plug. (can’t recall at the moment)
I mentioned this earlier about the supplied valve in the walbro kit, and questioned the long-term durability of it.
Now personally, I’ve always thought it was a formulation problem with the older valves themselves. You could argue that the material is much better now, and I’d agree with you. But the question remains of “upgrading” the stock material to another one, just as an experiment in durability and performance.

I not seeing any ill effects of this experiment. After looking into it, someone else passed the idea to make a valve with teflon, but from what I could tell, it doesn't seem like anyone really tried it out. If anyone has, let me know how it worked out.

So... does this sound interesting?

*and other carbs too.
[/QU
The teflon should work, hope you try it and let us know. I have made the little disc out of carb diaphragm material, thought the material was a little too thin so I bonded two layers together with crazy glue before punching one out. Some of the check valves in Zama carbs are made out of a stiff fibrous material that seems to be the answer to longevity. Next one I make will be out of teflon. If you want a really radical approach that eliminates the nozzle check valve but requires carb mods, read this post.https://www.arboristsite.com/community/threads/mac110can.295132/post-5857803
 
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