It's here!!!!............Inside the MS661

[Mastermind]

That would be cool. However, I'm not seeing this universal rule of 40° of primary compression. I've seen too many saws that run stronger when breaking that rule. Others run best like that. I just don't see trying to apply it universally. Again, every saw is an entity unto itself, and built accordingly.

Your right, it can't be applied universally.....there are always gonna be exceptions.

The 661 is a totally different transfer/case volume design from the MS660 that allows a long intake duration.......and I think it needs more case compression.

I'm just exploring all possibilities here.

 

[Trx250r180]

will the carb and coil off a 660 fit this saw ?

 

[Four Paws]

I think the 395 piston might just work.

Can you post the measurements of the 661 and 395 for everyone? I have the mag2 piston info below.

Total height 43mm
Comp height 23mm
pin 12mm
pin boss width 15.4mm
skirt width 35.5mm

Thin rings, too.

 

[blsnelling]

Your right, it can't be applied universally.....there are always gonna be exceptions.

The 661 is a totally different transfer/case volume design from the MS660 that allows a long intake duration.......and I think it needs more case compression.

I'm just exploring all possibilities here.

I'm down with that. I applaud you for testing it.

 

[big t double]

Can you post the measurements of the 661 and 395 for everyone? I have the mag2 piston info below.

Total height 43mm
Comp height 23mm
pin 12mm
pin boss width 15.4mm
skirt width 35.5mm

Thin rings, too.
View attachment 395163

weird...I just rebuild an 056mag and the wrist pin/clip was 13mm

 

[Four Paws]

Maybe I better check my piston and the box it's in.

 

[Mastermind]

Well the 395/394 piston will work by using a 2100 wrist pin bearing. The problem is that the case would need clearance work for the longer skirt....



The squish with the 395 piston is a easily manageable .053".

 

[Mastermind]

I'm installing the jug with the built up intake now.

I'm not planning to epoxy the intake on every 661 I build. Like Brad has said, the gains we can get with the intake at 85* are very good.......I'm just looking for the better.

 

[Stihlman441]

Is the run-on after a long cut characteristic for these M-tonic saws? Sounds like it takes about 2 seconds to return to idle.

This can happen with ported MTronics

 

[blsnelling]

It has nothing to do with porting. It's just a characteristic of MTronic sasws. Here's a brand new MS441C doing it.

 

[Mastermind]

Oh Bradley......

 

[blsnelling]

I'm ok with 200. That should be good.

 

[KG441c]

Brad what kinda problems come into play with more than 200?

 

[blsnelling]

Brad what kinda problems come into play with more than 200?

I simply don't find it's needed to make comparable power to a saw with significantly more. My customers confirm my opinions.

 

[Deleted member 83629]

i wouldn't want to go higher than 200 psi you might see detonation and pinging with that much compression.

 

[blsnelling]

It's more stress and wear on the bottom end, and frankly, don't find it's needed.

 

[Mastermind]

I simply don't find it's needed to make comparable power to a saw with significantly more. My customers confirm my opinions.

Who uses significantly more?

 

[Mastermind]

And who are all these customers?

I never see any of them post a word about your opinions.

Just sayin......

We all have "customers" and "cheerleaders". Why do you keep posting that?

Is there something you'd like to just say straight out?

 

[VinceGU05]

I'm installing the jug with the built up intake now.

I'm not planning to epoxy the intake on every 661 I build. Like Brad has said, the gains we can get with the intake at 85* are very good.......I'm just looking for the better.

Curiosity got the better of me. So I had a crack at welding a jug up.
Gotta say it's a buggar to get in there properly!!




Ground and stoned back. The nikasil looks great.

 

[singinwoodwackr]

that doesn't look like very good penetration...if any
try more heat