Part One: The Exhaust Port

[RIDE-RED 350r]

I guess I was meaning isn't the exhaust limited by the carb size? Or does that not really matter?

I don't think it really matters in this case. The carb and exhaust are not closely related in terms of working with each other like exhaust and transfer

 

[RIDE-RED 350r]

@Deets066 we need to stop typing at the same time! Lol!

 

[Deets066]

I beat ya to it.

@Deets066 we need to stop typing at the same time! Lol!

 

[Deets066]

I would say 65 percent would be safe. 75-80 would be pushing it, if your skirt even allows for that much

I never measure anyway, I just go as wide as my skirt will allow

 

[huskihl]

Thats pretty flat, it does make a difference. But it could hang at anytime

That's the saw your friend ran in ohio

 

[Miller Mod Saws]

O I likey so far. I'm gonna reread this up to this point. I do know one thing mostly coming from experience with customers. Almost all customers lean towards a torquey saw. Not all but most. The saw I've played the most on in all of this is a 7900 series Dolmar.

 

[RIDE-RED 350r]

Jump on in here Mr. Miller!

 

[XP_Slinger]

Ok fellas, bear with me on the drawing as I'm not the artsy type. But, anyone try a shape like this? Would give a flat area for rapid release of pressure and potentially better scavenging vs an oval but the ring would be safe. Not as optimum as flat all the way across but maybe a way to get part of the flat advantage. Justathinkin on this flat thing and the idea popped in my head

 

[huskihl]

Doesn't matter what you do to the exhaust port. It's all in the chain

 

[Deets066]

That's the saw your friend ran in ohio

It ran good

 

[Deets066]

Ok fellas, bear with me on the drawing as I'm not the artsy type. But, anyone try a shape like this? Would give a flat area for rapid release of pressure and potentially better scavenging vs an oval but the ring would be safe. Not as optimum as flat all the way across but maybe a way to get part of the flat advantage.
View attachment 68356

I wouldn't leave the corners squared like that

 

[Motorhead]

Guy that ported my snowmobile made the ex. port wider at the top and tapered back down to stock width at the bottom. He said it wasn't necessary to be that wide at the bottom

Gotta try that

 

[RIDE-RED 350r]

Gotta try that

^^^read my mind^^^

 

[XP_Slinger]

I wouldn't leave the corners squared like that

No sir definitely not. What do you think of the theory?

 

[huskihl]

My 346 could stand to be a bit flatter

 

[Mastermind]

I'm watching the TV with my beautiful wife.

I'll catch up tomorrow.

 

[Redfin]

No sir definitely not. What do you think of the theory?

Some older saws had ports roughly shaped as that but from what I have read it was to lower static compression.

 

[Stump Shot]

You gotta run the saw stock.......see what it feels like. Is it already sorta high strung, or is it something that you can really lean on?

I think @tree monkey said a lot when he told me that he studied the saws that loggers really held in high regard. Why did those saws run the way they did? How could he make other less desirable saws run that way?

These days I'm sorta locked into a production type of build. I spent a lot of time finding a "recipe" that was not too high strung, nor too torquey. Not too hard to start....and not prone to hang a ring or kill a crankshaft. I'm not looking for the fastest saw anymore, but I still wanna know I can build that mean ass machine when I need too.

BTW.......I love pie.

Problem number one, I rarely if ever start with a running saw, it's either a rebuild to begin with, or being built from scratch from parts piles. So I pretty much have been going on blind faith, with a little know how, from one saw to the next. Not really having the luxury of extra time to build it twice. I should however try to make the time to see what these saws degree out at and take more notes, this is something I can do. I see your point, there was one saw in particular I built, that really stood out above the rest, wished I would have checked the numbers on that saw, but it had to go down the road.
Second, without a big base of saws out in use stock or not, it's hard to get that amount of feedback, so I have to go with assumptions from a small amount.
Thirdly, been taking a real conservative approach to the whole mod thing for other peoples saws. This safe approach does not lead to finding boundary's. These saws have to run and do a good job for people first and foremost.
Fourth, come June, a small used lathe and 90 degree hand piece is being donated to me, so the game is going up at a faster rate than I am, or so it feels.
Five, all your answers make me believe that you watched the show Kung Fu a lot as a kid. Lol

 

[Deets066]

No sir definitely not. What do you think of the theory?

I think you are giving it a smaller area to vent when it first opens. Yes it's flat but not near enough area I think

 

[Miller Mod Saws]

On a 7900 I've got to tear down several that my loggers have ran the piss out of. On this particular saw. This is what I like. And remember I build these differently per the customer. but the ones that seem to run the best and wear great. Are like the left pic and I'll explain. The right pic is more arched with straighter side walls making for a huge exhaust. But has a nice curve so not to hang a ring. But both let's say 70% width. The left one is super flat on top but then has a big corner that drops a a steeper arc to mid port. This style seems to flow just as well but not pit as much skirt wear on. The bigger the port seems to really wear on the bottom of the skirts faster.

Thoughts.?
Apologize for the pics as the suck. But hopefully I got what I was trying to say across. lol.