Miller Mod and the PS-421 dolmar.

[Miller Mod Saws]

 

[Miller Mod Saws]

Now usually I grab measurements for percentages for you guys. I havnt yet. But I'll try and remember. When I tear the next one down. The exhaust and intake can be widened quite a bit on these saws. In still in the safe zone by far. I widened both till they were about 2mm from port edge to skirt edge then I flattened the intake floor and set it a 76 degrees. The the exhaust I flattened as well but still left some curve curving more as it gets close to the edge.

 

[Miller Mod Saws]

This is where most of my time was spent. You may think open trans should be easy to grind. O these are a beotch!

 

[Miller Mod Saws]

Now this is about mid testing to where I'm at now. So far I've set my intake at 76 and havnt budged from that. This saw seems to be responding a lot like a dual port would. I will test the intake height later on. At this point I would saw I'm at a ballpark 20% gain. This is also the point I switched wood

 

[Miller Mod Saws]

As I'm bringing the port timing up slowly I've tried more and less blowdown. But I'm not gonna waste your time with all of that. This final saw I will show is sitting right here.
Ex 105
Trans-122
In-76

 

[Miller Mod Saws]

Now 17 degrees is as high as I have went in the trans as well. There at a flat 122. And I have kept the roofs of the ports fairly flat.

 

[Miller Mod Saws]

I and one more piece to this puzzle which made a very big difference. At this point I've advanced the ignition timing 6 degrees. Why 6. Well that works good on the 5105 so that's where I started here.

 

[Miller Mod Saws]

 

[Miller Mod Saws]

Now I have one more vid. But at this point my makita is at 107/125/76. Dolly at 105/122/76. Im going to play with the timing a tad on both saws but leave them here for now. As the gains are getting smaller the saws not being broke in and both on there first tank of fuel is factoring in.

 

[Miller Mod Saws]

In this vid I just did 2 thing picked a bigger tree so ya could see how this saw that's not een broke in yet is still pulling very hard and 2nd. I switched the chain to stihl ps. Instead of the factory semi chisel.

 

[CoreyB]

Looking great. The 421 is a great little firewood saw. Price wise even ported probably is not much more then a 241

 

[Miller Mod Saws]

I'm sure I've left some out so fell free to ask away. These saws arnt done yet but this is where I'm at.

@Red97 hope ya will jump in here as I know ya did a build thread awhile back. Put your 2 cents in or fifty dollars heck I don't care. Lol.

 

[Miller Mod Saws]

Looking great. The 421 is a great little firewood saw. Price wise even ported probably is not much more then a 241

I'd haft to look up the price for sure but ported at you door should be just under $600.

 

[Miller Mod Saws]

Here's my regrets. When I first bought the 500p echo. I wanted throw it in the ditch. Lol. The 421 stock for stock would eat it's lunch. Well after porting the 500p is an awesome little saw. But it's since found a new home so I can't compare the 2 ported. Lol.
I may fire up a stock 5105 and see where we land there though. It won't take a ported one I know that.

 

[WKEND LUMBERJAK]

@WKEND LUMBERJAK would you snap a pic of the 5105 mod. Please.

The Muffler?

 

[WKEND LUMBERJAK]

 

[Miller Mod Saws]

The Muffler?

Yes thank you! I knew you would be able to see the screen in it. Lol.

 

[ajschainsaws]

I didnt get chance to get good photos on my 420 but you've got it I a nutshell great pics that chassis is built to last for sure

 

[WKEND LUMBERJAK]

Yes thank you! I knew you would be able to see the screen in it. Lol.

The pic is from the 5105 thread.LOL

 

[Miller Mod Saws]

The pic is from the 5105 thread.LOL

Why didn't I think of that. Lol.