Building another hotrod MS661C

[blsnelling]

This saw is for a local arborist that's been in the business for many years. Most of his saws were recently stolen and I've been helping him get back on his feet with new saws. Up today is his new MS661C. @treevet

 

[blsnelling]

Here is the saw bone stock. It only made one cut before this video was shot. They run mighty nice for a stock saw.

 

[blsnelling]

Pulling the flywheel.

The key is a little over .075" thick.

I file down the portion that sticks out of the crank so that the flywheel can be indexed CCW in order to advance the ignition timing.

 

[blsnelling]

Squish from the factory was .033"-.034".

Once I know the squish, the cylinder comes off and I can do the machine work.

I just touch the bottom of the piston skirts in order to make sure they're square with the crown.

I then turn a popup on the piston crown. I give the edge of the popup a 45° angle.

 

[blsnelling]

This is just one of the rough cuts on both the piston and cylinder.

 

[blsnelling]

Here you can see where I did a little porting on the transfer intake duct.

Squish after machining was a strong .020", right where I wanted it.

I check the squish on all 4 corners. This is partly to make sure the popup isn't too close to the edge of the combustion chamber.

Setting up the degree wheel.

I've found through testing that completely removing the baffler is the best way to go.

I will cut a new screen with more open space in it. If this weren't a daily work saw I'd also add gills to both sides of the muffler cover. In this case, I'd rather keep the volume down a little.

That's it for now. More to come later.

 

[user 122190]

I once thought that if I ever need some custom work done on a saw, I'd just do it myself. Hell, I have a dremel tool.

Now, I'm going to send it to you.

 

[SCHallenger]

 

[Chainsaw Jim]

Lookin good. I can't wait to see the after video.

 

[Whitty21]

One of my life goals is to completely tear into a NIB saw

 

[blsnelling]

My photo editing software does some weird stuff to cylinder pictures. Please ignore the "dark marks".

 

[marti384]

Looks good. It seems like it has been a while since I have seen any new build threads here.

 

[Woos31]

As always great work B-rad and thanks for sharing the photos and explanation

 

[zogger]

Lathes sure are handy...

 

[blsnelling]

She's done and runs fantastic.

I only remove the casting lines here.

All done and back together.

 

[banana boat]

Wheres the after vid?

 

[blsnelling]

Wheres the after vid?

It's uploading now.

 

[banana boat]

Sweet

 

[KiwiBro]

What guarantee is there this one won't suffer faults (not of your making I should point out) as the other one did? Especially in light of the OEM warranty being voided by the modifications?

 

[blsnelling]

I thought I was going to have to wait until Monday to make the after mods video, but my sweet wife held the flashlight so that I could make a video at 9:30 at night