Help with K760 saw

[Agrarian]

Maybe 15psi or more. And as Duce said above, you should remove the muffler and take a peek at the piston and intake side of the cylinder from the exhaust port. There could be a good clue there.

 

[jpcjguy]

The video in an earlier post is through the muffler port - can you all see that?

 

[Al Smith]

Cut-off,stone saws ,demo saws or whatever you want to call them operate in a really bad environments .They have better air filters than say chainsaws but injest a lot of abrasive particles .As such worn piston rings are not to be surprised . Generally speaking piston rings are not that costly and relarively easy to install .Fact you could use higher quality after market rings such as Caber which would work if you could find them .

 

[Agrarian]

The video in an earlier post is through the muffler port - can you all see that?

I see photos in earlier posts but no video.

 

[Duce]

I think you will find that is a Partner saw.

 

[jpcjguy]

I see photos in earlier posts but no video.

Post number 3 - link to it (think I have the sharing permissions right): https://photos.app.goo.gl/z6LCmjakHUzaNNfj8

 

[jpcjguy]

Cut-off,stone saws ,demo saws or whatever you want to call them operate in a really bad environments .They have better air filters than say chainsaws but injest a lot of abrasive particles .As such worn piston rings are not to be surprised . Generally speaking piston rings are not that costly and relarively easy to install .Fact you could use higher quality after market rings such as Caber which would work if you could find them .

So a set of rings like this? I heard Caber are good: https://www.ebay.com/itm/172891956792

 

[Al Smith]

They'd work fine

 

[jpcjguy]

Can someone tell me if they can see the video?? If anything to let me know the sharing worked?!?! (darn google photos!)

 

[Agrarian]

Can someone tell me if they can see the video?? If anything to let me know the sharing worked?!?! (darn google photos!)

Yes, I can see it now.

 

[jpcjguy]

Took it all apart - what do you all think?

How much connecting rod play should exist - to me this seems excessive but then I have never been in one of these!
video: https://photos.app.goo.gl/rCcPFsn5ARAVphWP7

another video of connecting rod: https://photos.app.goo.gl/JJpTjj44ow251XQ68

 

[jpcjguy]

more pics

 

[Agrarian]

That color change in the cylinder wall indicates the plating is worn through which is common on those saws. You should be able to feel a very slight ridge between the two colors (plating is only a couple of thousandths). If I'm right, it's not something that can be fixed - time for a new top end. That certainly would explain the low compression.

 

[Duce]

Not a cheap oem repair. Also look a Partner 750/760 parts.

 

[jpcjguy]

Thanks everyone for helping me. I do appreciate it. I was expecting a top end. But what do you all think about the connecting rod play? There is a lot of slop - or so I think….

 

[Agrarian]

The biggest concern with crank play is the radial type. Put the crank at the top of its stroke. Then see if there is any slop when you push and pull the conrod straight up and straight back. Hard to describe but easy to check. If there is any play, the crank is bad.

 

[jpcjguy]

Here are 2 pics of the rod when I push it from one side to the other

 

[Agrarian]

Sliding side to side is normal and actually necessary to allow for minor alignment variations with the piston and cylinder. And some rocking sided to side is normal. It's the up and down play that can't be tolerated.

 

[jpcjguy]

ok. When I pull up and down there is no give so I guess I can assume that it is ok?

Another video https://photos.app.goo.gl/cxFLoPJKce8uYRAJ6

 

[Agrarian]

Yes but I did hear a click in the video when you were doing the up/down test. Was that from something else? The twisty test you did shows that there is a fair amount of wear to the bearing but it would work if there was no up/down play. For the limited use that you mentioned you had for this saw, a piston/rings/cylinder/piston bearing replacement should get it working for your needs.