Mastermind Meets The MS500i

[Lightning Performance]

Very common on these newer Stihls. One over the intake port.....the other beside the exhaust.

MS361 I believe started that trend.
Have to go catch up tonight. Got done early...Friday Mfers!
Which means nothing at my age...

 

[Mastermind]

Is the wrist pin 13mm Randy?

12mm

 

[MG porting]

So.....factory squish of .027.

54mm bore. No windows in the piston.

View attachment 217837

Not bad for squish.

 

[XP_Slinger]

12mm

Dammit

 

[Mastermind]

These numbers are after machine work.....

Ex: 110°
In: 87°
Tr: First point of opening is on the exhaust side at 124°, at 130° both ports are flush with the top of the piston. At 133° the intake side is flush with the piston crown.

 

[MG porting]

These numbers are after machine work.....

Ex: 110°
In: 87°
Tr: First point of opening is on the exhaust side at 124°, at 130° both ports are flush with the top of the piston. At 133° the intake side is flush with the piston crown.

Should be a torque monster with those numbers.

 

[XP_Slinger]

These numbers are after machine work.....

Ex: 110°
In: 87°
Tr: First point of opening is on the exhaust side at 124°, at 130° both ports are flush with the top of the piston. At 133° the intake side is flush with the piston crown.

Dang. Intake must have been around 80 before the cut.

 

[Mastermind]

Dang. Intake must have been around 80 before the cut.

About 83 I figure.

 

[Agent Smith]

Im guessing some epoxy will be in the intake? Im still learning here

 

[Mastermind]

Fixin to cut out.....my wife's sister is having a birthday party. She don't know about it yet......but Glenda done made the cake.

 

[Mastermind]

Im guessing some epoxy will be in the intake? Im still learning here

I'm doing four of these. They will all be a little different. At least one will have epoxy on the intake floor.

 

[Lightning Performance]

Did she ask you why? If so post pics of what she did to you after you told her.

You'll have to go to another site. He can't be postin you all his bidnesses

 

[Mastermind]

Fixin to cut out.....my wife's sister is having a birthday party. She don't know about it yet......but Glenda done made the cake.

I'll be back on this in the morning. Hang tough.

 

[Lightning Performance]

Sounds good.

Ten degrees is a large sweep to cover.
Smooth

 

[MG porting]

You'll have to go to another site. He can't be postin you all his bidnesses

I don't do the other site Bedford is there making a ass out of himself.

 

[Dub11]

I'll be back on this in the morning. Hang tough.

You should take the weekend off, ya just quoted yourself.

 

[drf256]

Depending on bore percentage width of exhaust port as it stands, I’d be fixin to lose that bottom ring if it needs some widnin.

With fuel injection, I’m not so sure as much negative case pressure is needed as in a Venturi fuel flow based saw. Your experimentation will spell it out. I bet the intake is fine as is.

I hope at least one experiment is to leave all the ports after the machine work the way they are now and just slick ‘em up. I do think 110* is real low for a saw of that displacement, but you have 40-46* of case compression if I’m doin my numbers right. Wide bore, short stroke.

You’re hitting 110 a lot faster with that short stroke than one would the other way around. 54mm and only 79cc.

At least that is how I see it, but who really gives two shíts what I think, lol.

What I see is them using all the tech and not being as limited by carburetor EPA issues. I believe the factory timing being set more where we would want it is telling us a story here.

 

[drf256]

Just another thanks from us for taking the time to do this thread and share Randy. I know it takes extra time, and they ain’t makin any more of that.

 

[Stihl working Hard]

Just another thanks from us for taking the time to do this thread and share Randy. I know it takes extra time, and they ain’t makin any more of that.

+1 from me as well Randy awesome thread

 

[Mastermind]

You should take the weekend off, ya just quoted yourself.

Meh

Depending on bore percentage width of exhaust port as it stands, I’d be fixin to lose that bottom ring if it needs some widnin.

It's pretty wide.....and working saws are us....so I intend to keep the bottom ring.

I would love to move the pin though.

I bet the intake is fine as is.

I bet you are right, and why I'll just epoxy one jug to test that theory.

I hope at least one experiment is to leave all the ports after the machine work the way they are now and just slick ‘em up. I do think 110* is real low for a saw of that displacement, but you have 40-46* of case compression if I’m doin my numbers right. Wide bore, short stroke.

I'm not planning on leaving the exhaust that low.....but 105° is as high as I "think" it really needs to go. But...to test its reaction to increased blowdown, I'll be doing 102° on one of them.

You’re hitting 110 a lot faster with that short stroke than one would the other way around. 54mm and only 79cc.

Yep....not a lot of meat above the port. Gotta remember the 661 though. 56mm bore. I take the exhaust way up on that saw. It loves blowdown.

At least that is how I see it, but who really gives two shíts what I think, lol.

Well.....I do.

I believe the factory timing being set more where we would want it is telling us a story here.

They ain't playing around. Stihl has been doing their R&D.

Just another thanks from us for taking the time to do this thread and share Randy. I know it takes extra time, and they ain’t makin any more of that.

+1 from me as well Randy awesome thread

Worse time for me to pick to do a thread fellas. I was up most of the night coughing. I'm not feeling so sporty today.