Mastermind Meets The MS461

[Mastermind]

Here's some of the mandrels I've made to fit different cylinders....



Here you can see that I've changed the chuck to a three jaw, and am using a UHMW mandrel to mount the jug in the lathe.



Sorry about the blurry picture.

I use an aluminum plate, with a small hole drilled thru it, between the live center and the top of the jug to allow me to bump the cylinder around when centering it in the lathe.



Then I set up the dial indicator to read the mandrel as close the the base of the jug as possible.



Bump....



Bump....til the runout is gone.



Now we are ready to turn the base.

 

[Mastermind]

Spin, baby, spin.

 

[Mastermind]

Now we add a chamfer to the edge of the bore.



Check squish again. Note that I use as thin a piece as I can.



.025 it is.

 

[Mastermind]

Now we set up a degree wheel to check and set port timing.

I use 1/16" SS tig wire for my pointers. You just need a good place to mount the pointer.



And this is what we use for a wheel.



Mounted to the crank with a 1/2" drill chuck. Mike (Homelite410) made me a couple of these .125" thick X 7" aluminum wheels. They work perfect, I just print my wheels to size on heavy card stock, and glue them on with Super 77.

 

[Mastermind]

Here what I use for a piston stop. It's just an old spark plug with the insulator removed, and the center tapped for a 3/8" bolt.



Here's a video showing how to set up the wheel and find TDC using a piston stop.

 

[Miller Mod Saws]

Excellent randy. I have yet to get to play with a 461. I want to bad. Lol. Future question are headed your way. When ya get to the trans my questions are gonna come. Lol. Awesome work as always

 

[Mastermind]

This is my spec sheet for the MS461....

 

[Frank bierce]

Lovin all the pics and videos. A little too much of a simpleton to read . Nicely done

 

[Mastermind]

 

[Mastermind]

Here's a shot of the upper transfer ports when they were just roughed in to the correct height. I try to make the corners as tight as I can on these so that they flow as much as possible when they first open.





These are the various burrs I've used on these upper transfers.



In this picture you can see what I was talking about in the video. I cut the port upward until I contact the card stock. The pencil lines are to control the width. As you can see, I don't widen the exhaust much at all. IMHO the shape of the port, and height, means far more than width. An overly wide port just wears the rings out faster.



On the 461, and most Stihl saws, I use the heat shield as a template for port matching the muffler to the jug.

 

[Mastermind]

The exhaust roughed in.





The intake marked up....again, I don't widen this port much either.



This is a shot with one side roughed in. It gives you an idea of what I'm looking for in shape compared to the stock port.

 

[Mastermind]

And a few shots of me grinding....

 

[Mastermind]

I use several different grits of emery cloth and ScotchBrite when finishing the port work. Here's some of the shop packs of emery cloth.

 

[Mastermind]

I'm gonna do the finish on the port work now. Jon has been working the muffler over......and I'll have pics of that process later too.

 

[Mastermind]

The transfer entrance after cutting the base.



And now.



Here's some shots with the finish at 80 grit.





In this picture you can see the bevel I added around the intake port.



The transfers thru the exhaust....I just wanted to see if I could get this shot.



The intake is finished. 80 grit is as far as I take it.

 

[Mastermind]

Now the port work is finished, and the jug is ready to put back on the engine. I feel like I've done a good job on the porting when it's not obvious what all I've done. I had a fairly well known (but not very well liked) saw builder tell me that he had one of my engines apart, and that all he could see was that I had shined up a few things in it. I then told him that I also had been in one of his......and that it looked like something my grandson would do with a burr. That bastard hung up on me.

In these pictures notice that I've rounded the edge of the squish band here. You should also be able to see a small bevel around the port edges.

 

[Mastermind]

Now for some pics of the muffler work.

Jon starts by removing the whole baffle from the shell. In this pic you can see that he's center punched the spot welds and highlighted them with a black marker.



Then he drills the spot welds thru the baffle, but not all the way thru the shell.







The top attachment point is yet more spot welds, they are cut thru with a round carbide burr.



And she's outta there!!!!

 

[Mastermind]

Now to match the muffler shell to the cylinder. Again we use the heat shield as a template.





We use a mesh screen that is more open in mufflers that will still accept a screen after the mods.



I didn't have a good picture of the side outlet......I will get a better one when the muffler is complete.

 

[Mastermind]

Now for the cover.

This is an OEM MS460 cover that I've been hoarding...this is a good place to use it I think.



They have a pretty small outlet from the factory......Jon fixes that.



Ready for paint....



Wiggs turned us on to this trick. Heating the muffler before painting it makes the paint dry as it hit the part......and it seems more durable.



More later after it's all buttoned back up.

 

[Mastermind]

The timing numbers.

Intake...



Exhaust...



Transfers...