Fixing a 15 year old 066 Magnum/need advice

[Jungleman]

Hey all. I’ve got a project I want to work on but before I get started I had some questions. I’m a bit of a rookie mechanic so be patient with me.

I bought this saw 15 years ago as a gift, am told it ran for 3 years then something broke and it was too expensive to fix so it was put on a shelf. I got my hands on it last month after more than a decade of asking for it back. Long story. Now that I have it back I want to use it to learn how to take apart a saw and fix it and put it back together. I’m in no rush to get this done quickly. Gonna take my time and do it right.

I’m positive it has all the original parts and has not been tinkered on. So new original OEM p&c. I’m hoping I can clean those and re use them. I’ll attach pictures. If I have to buy a new piston and cylinder I will not use oem, I called my Stihl dealer and it costs 450. Not gonna happen. I’d rather buy a meteor or whatever is most recommended by those more knowledgeable than myself. I still have a few more tools I need to find before I can get started. Been lurking here a while watching videos and I’m gonna try to clean my cylinder with masterminds way. Just gotta find some pieces of Emory cloth without buying a 500 ft roll on eBay!

So my first question is this. When I pulled the cord to test the compression it makes a clanking nose I’ve never heard before in a chainsaw. I wish I had made a video before taking it apart..... it did not sound good. I bought a cheapo compression kit and it only read 30 psi..... but I checked the compression on a 1 year old ms 391 and it read 75 psi even though the saw runs great so I’m gonna ignore the compression for now.

What’s the clanking noise? I will attach a video of me turning the flywheel by hand but it just makes a little clicking noise.

I think I’ve written enough so far. I blame the bourbon.

 

[Jungleman]

 

[Jungleman]

Piston

 

[Jungleman]

Cylinder

 

[Jungleman]

Video of clicking

 

[Jungleman]

More pics

 

[Nutball]

I'll guess shot con rod bearings or the rings might be slapping the piston during the up/down stroke transition.

 

[beaglebriar]

Could be bearings, could be piston slap. Tear it down... you're already there anyway.

 

[beaglebriar]

That cylinder will clean up with a little sandpaper and some elbow grease. Don't use power tools unless you have to.

 

[Wonkydonkey]

Now you got the cylinder off, you may as well take the piston off, it more than likely you need a new one.

Give it a spin over like you did before, and hold the conrod while doing it.

As beaglebriar says the cylinder will clean up...

Look at this thread
http://opeforum.com/threads/how-to-remove-aluminum-transfer-without-acid.357/

 

[Jungleman]

Now you got the cylinder off, you may as well take the piston off, it more than likely you need a new one.

Give it a spin over like you did before, and hold the conrod while doing it.

As beaglebriar says the cylinder will clean up...

Look at this thread
http://opeforum.com/threads/how-to-remove-aluminum-transfer-without-acid.357/

Yes that is exactly the video I’ve watched a few times and plan on using that same method on the cylinder.

 

[Jungleman]

Could be bearings, could be piston slap. Tear it down... you're already there anyway.

Piston slap..... I’ll look up what that is.

I’m also worried it’s the bearings. They seem like a pain in the arse to change but I’m up for it if that’s what’s needed!

 

[Wonkydonkey]

Looking at the piston and cylinder, there’s not much carbon, this saw has not seen much fuel

 

[drf256]

Basically you have to split that case, get it down to it’s primal parts, and inspect everything. Especially the pin bearing and large rod end bearing on that crank. The large bearing isn’t replaceable.

 

[Jungleman]

Basically you have to split that case, get it down to it’s primal parts, and inspect everything. Especially the pin bearing and large rod end bearing on that crank. The large bearing isn’t replaceable.

If I have to split the case that's gonna take some more video watching as I dont even know where to begin. Take off the fly wheel and go in from there I assume? I gotta research that. I took the piston off and the rod turning seems pretty smooth now and has no sideways play in it but that's from an amateur point of view. I'll put up a video of it.

Could it be the piston which was the problem? Is that what could cause the noise? I dont mind getting a piston and putting it in and putting it all back together o ly to find out that wasnt the problem. Just means I get to take it back apart again, fun!

Can you elaborate on the large bearing is irreplaceable. It cant be bought?

 

[Jungleman]

 

[exSW]

You are right where I am with mine. In fact I just bolted the jug back on without the piston. I'm going to block off the intake and exhaust and do a vacuum and pressure check off that little black impulse line.

 

[BuckthornBonnie]

The big end bearing of the crank isn’t replaceable, right. Still hard to say for sure based on that vid above. Does the shaft have any vertical play if you lift it away from the lobes? There’s a needle bearing in there that needs to be inspected.

 

[Funky sawman]

Looking at the piston and cylinder, there’s not much carbon, this saw has not seen much fuel

Well I usta say that too, until I switched to red armor oil. The last 660 I built had over 300 hrs on it and the guy i sold it to wanted me to do a tear down and clean up ports and change the rings so its fresh for the this next season of cutting timber. The piston and chamber in that saw looked like new. Only difference was that he switched to 50 to 1 red armor instead of 40 to 1 like I run.

 

[Funky sawman]

I say over 300 hrs because that's the billable hrs that he accumulated felling timber since he bought it. Then over 100 cords of wood, so hard to keep tract of hrs that way