Mastermind Revisits The MS261CM Type II

[Mastermind]

takes fuel to make power

Are you gutting them Scott?

 

[Onan18]

Basically the fresh air is creating a "Dam" between the fuel charge and the exhaust gasses (pressure differential) and pushes the spent gasses out of the exhaust port so less of the fuel charge is lost out of the muffler before having a chance to ignite and do work.

I cannot take credit, it is how they dumbed down the theory of operation so they could explain it to us mechanics at the service school.

Useless trivia: Does anybody know who pioneered this technology?

 

[Termitebuffet]

Ready to port these mfers.......

View attachment 89792

Got a couple new smoother ones....lol

 

[Adirondackstihl]

I cannot take credit, it is how they dumbed down the theory of operation so they could explain it to us mechanics at the service school.

Useless trivia: Does anybody know who pioneered this technology?

Zenoah

 

[tree monkey]

Are you gutting them Scott?

nope. I don't see a reason too

 

[Onan18]

Zenoah

Negative, Zenoah was the first company to implement it, but a man named Honda designed the first Strato engine.

 

[tree monkey]

Negative, Zenoah was the first company to implement it, but a man named Honda designed the first Strato engine.

do you know what year it was patented?

 

[retro]

As far as I can tell Randy, you pioneered this strato-intact 261 porting method (I read about it on your MS261 VS MS261 C-M Comparison thread on another forum site) four years ago this month. I'm sure you've refined your methods an awfully lot since... and the saw got a major face-lift. With all that in mind, do you think these type II 261s are any stronger running than those OE models were after your porting & mods? Have you found better port timing numbers (or come up with any other tricks) since?

 

[Adirondackstihl]

Negative, Zenoah was the first company to implement it, but a man named Honda designed the first Strato engine.

You’re so difficult
Next time be more compliant with my answer

 

[retro]

nope. I don't see a reason too

http://opeforum.com/threads/saw-video-thread.196/page-471#post-509716

... as long as the customer gots two strong hands!

 

[Mastermind]

As far as I can tell Randy, you pioneered this strato-intact 261 porting method (I read about it on your MS261 VS MS261 C-M Comparison thread on another forum site) four years ago this month. I'm sure you've refined your methods an awfully lot since... and the saw got a major face-lift. With all that in mind, do you think these type II 261s are any stronger running than those OE models were after your porting & mods? Have you found better port timing numbers (or come up with any other tricks) since?

Let me just say this......

I second guess myself sometimes. When I do, I build several saws of the same model with slightly different timing numbers or with different methods. For instance, one might have the stratos gutted, one might have staggered transfers, another will be the tried and true recipe I've done so many times before. They all run very well........and the customer is happy either way. But.......I learn more each time I change it up. Sometimes I tweak my recipe because of these trial and error batches I do.

The new version was a slight step backward in performance to me. That is because the newer version has a higher exhaust. It works out better really though, because the exhaust height comes in closer to where I want it after machine work.

The real improvements were in better cover seal, and weight.

 

[Mastermind]

 

[Mastermind]

Putting them together now........mufflers next.

 

[Adirondackstihl]

I see something weird in the cylinder extensions.
Are they taper cut on the sides?

 

[Mastermind]

I see something weird in the cylinder extensions.
Are they taper cut on the sides?

They are now. Yes.

 

[Onan18]

do you know what year it was patented?

No sir I do not, they told me in service school years ago, but there has been far to much cheap booze and wimmins between then and now for me to recall anything that specific.

 

[Lightning Performance]

The shape of those exhaust ports is unique. Flared bell. Smooth job. I like it on 361 and 2's.

That transfer fresh air loading causes thermal shock. That might explain the early seizures. They might have been too tight for cold weather operation after pit-stop cooling offs or they needed more meat in the lower transfer bridge to stop the "pinch." Those jugs look like nice castings to work with. Small but meaty.

 

[retro]

Thanks for your insights Randy! I really like those D-shaped floors, walls and roof profiles in the exhaust port. Nice looking squish band & combustion chamber work too! Top drawer stuff!

 

[retro]

I see something weird in the cylinder extensions.
Are they taper cut on the sides?

Those reliefs are provided for the main bearings clearance I think? Counterweights too maybe...?

 

[MustangMike]

Thanks for sharing such detail Randy, other than the transfer slopes, the stock #s and squish seemed real good!

Your work, as always, looks excellent.

I needed some good news tonight, cause I also got some bad news. One of my old friends, a guy known as Wolfman, passed last night.

Back in the day, Wolfman worked as a bartender/bouncer at Dutchy's Den, the hottest spot in Peekskill, along with two of my other friends Baby John & Goon. All 3 were over 6' and 200 lbs. That place was my regular hang out till I got married, and I even had my first wedding reception there (we met there).

Wolfman had long blond/brown scraggly hair, and a beard to match and always greeted you with a smile. He subsequently worked for Metro North RR.

Baby John passed several years earlier, but Goon is still with us. Don't know what ever happened to Dutchy, but he was a larger than life person who treated everyone he knew like family.

At my 25th birthday party (my last before marriage), Dutchy and the boys all came, and when we killed the 2 kegs of beer, he called the bar and had them send more. We floated 8 keg that night, and I still run into people who talk to me about that party (two of my friends started a lawn mower in the living room).

When the State Police came to ask us to keep the noise down, the Trooper said "we don't want any trouble..." Goon stopped him right there and said "If you don't want any trouble, then leave". I intervened and told Goon to shut up and apologized to the Trooper. I guess he had sympathy for me cause he left us alone. But, it was a good party!

On another occasion, Goon got arrested for taking a Trooper's hat and not giving it back, he had to call for backup.

RIP Wolfman, you, and your big smile, will be missed.