What's the Dope on 372 52mm setups??

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A lot of people who port a lot don't talk because most of it has already been said.

People like me just hack until they get something good. We're not experts, so what are we qualified to talk about?

There are good threads out there on porting 372. Some have good numbers. The loss of photos is a huge bummer, please post yours!

Interesting you would say that. The research and conversations I've had with people on the subject suggest the opposite. Bump in compression, added intake, and a lighter piston. I generally hear it'll make a strong saw without any port work done.

I personally have not done the 268 mod myself as of yet.

I think what Huskihl was saying was don't buy the 268 popup. You're just going to cut it off. That's what Trappermike said too. I think a normal 268 piston has enough on it to make a tall popup if you deck the cylinder.

If there is a known brand of BB 372 cylinder that has good plating, please post it. Not being able to reliably port AM cylinders is a disappointment to us all, so please name names! I can vouch for Meteor jugs having nice plating. Casting is sometimes worse than OEM and my meteor jugs have very aggressive chamfers on the ports. I don't believe Meteor makes a 52mm jug.

Related to the 52mm big bores, the OEM 51.4mm XPW cylinder is available for $150+ if you want a guaranteed quality cylinder, though they require a lot of grinding to perform. I don't know of a popup option for that jug (maybe Dominant) but I bet it's been done.

@mixxer a 50mm used oem jug can be ported very successfully to make a 372 pull a 28" through almost anything. If you're after torque and ease of operation 50mm OEM may be cheaper and more reliable ported. If a 372 isn't handling your trees a 390 is pretty great!
 
Lol I wish I had someone like you here to compete with. I build my mates saw and my then go race him. It's just not the same. If by mid range you are looking for around the 10k mark I'm more 12-13k in the cut. But then I want to put on a 30" by to drop these old pines and bust down the butt end. Poor saw, I have many expectation's. Be buggered if I'll give in and get a bigger saw though at least not yet. I'll fight it out till I get my saw!
I'm very interested in how you go about your build and what numbers you settle on to try. I'm picking you are thinking around the ex 170 mark with say 28 degrees of blow down??
 
A lot of people who port a lot don't talk because most of it has already been said.

People like me just hack until they get something good. We're not experts, so what are we qualified to talk about?

There are good threads out there on porting 372. Some have good numbers. The loss of photos is a huge bummer, please post yours!



I think what Huskihl was saying was don't buy the 268 popup. You're just going to cut it off. That's what Trappermike said too. I think a normal 268 piston has enough on it to make a tall popup if you deck the cylinder.

If there is a known brand of BB 372 cylinder that has good plating, please post it. Not being able to reliably port AM cylinders is a disappointment to us all, so please name names! I can vouch for Meteor jugs having nice plating. Casting is sometimes worse than OEM and my meteor jugs have very aggressive chamfers on the ports. I don't believe Meteor makes a 52mm jug.

Related to the 52mm big bores, the OEM 51.4mm XPW cylinder is available for $150+ if you want a guaranteed quality cylinder, though they require a lot of grinding to perform. I don't know of a popup option for that jug (maybe Dominant) but I bet it's been done.

@mixxer a 50mm used oem jug can be ported very successfully to make a 372 pull a 28" through almost anything. If you're after torque and ease of operation 50mm OEM may be cheaper and more reliable ported. If a 372 isn't handling your trees a 390 is pretty great!

New people come and go from these forums all the time. So as far as I am concerned there is always a fresh answer to a question. I particularly hate it when guys respond saying just go search for the answer. It shuts the discussion down. Every single forum I known goes stale and a pecking order develops and slowly but surely a culture forms were no one wants to share for fear of getting flamed. That's about where I think this site has ended up. If it wasn't for mixxer and Tappermike I'd bugger off and do my own thing again because you won't learn anything new here.

I have no idea who you are or what you do but I can almost guarantee you have been at this longer than me. I doubt there are too many experts here and the few there are tell you nothing so I say to hell with it and us amateurs can help each other by sharing our mistakes and success.

You say a 372 can pull a 28" bar through almost anything. Great, how do we set it up to do that? Both myself and mixxer have the gear and the inclination to build it.

I think the 372 I have just finished would pull a 28" well but not like a 390. I know my port timing is possibly too high to get great torque but it would be great if someone like yourself who knew the magic numbers would say to save us the hassle of incrementally cutting ports till we get it. Your finial sentence is a classic case of I know how but I'm not telling you. Which is case and point what I have encountered on almost any forum. Why not just share what you know?

Please don't take offence to what I'm saying as I'm really directing this to anyone who reads it. I think if a few of us start sharing everything others will join in. In no time we will have an awesome resource of information because despite your belief that there is a lot of info here I can honestly say I never really found it. A small nugget here or a number there but no bullet proof recipe to build a good saw.

I don't want to sound condescending although I know it will, guys who want to clean up ports with a Dremal are not on the same level as those of us who have spent a small fortune on tooling and really want to build monsters. I want a screaming cooki cutter with a stock muffler. I have not yet built it but I haven't finished building either. I will get there because I never give up and I have deep pockets to feed my addiction. The cylinder I have just done is good but not at expectation. I have some meat left in it and will consider carefully whats bits come out next.
 
My buddies saw a few years ago.



One of the last was I ported before I quit porting



Probably the best 50mm jug I ever did

 
My buddies saw a few years ago.



One of the last was I ported before I quit porting



Probably the best 50mm jug I ever did



Nice! they have about the same exhaust note as my saw but you are getting more torque than I have. Question is how did you do it?
 
New people come and go from these forums all the time. So as far as I am concerned there is always a fresh answer to a question. I particularly hate it when guys respond saying just go search for the answer. It shuts the discussion down. Every single forum I known goes stale and a pecking order develops and slowly but surely a culture forms were no one wants to share for fear of getting flamed.

Not saying you're wrong but you're really over simplifying it.
As much as discussion is good and leads to fresh ideas, it's also good to do your homework and build from a basis that has been established by the experience of countless people that is exhaustively documented here and other sites.
I realize it's a daunting task to ferret out the good info from all the garbage but the info is indeed out there for the taking.

People with many years of experience who were once a wealth of knowledge here get burned out repeating the same info year after year, only to be second guessed by the never ending latest batch of semi enlightened newbs then wanting to be spoon fed exhaustive explanations/justifications to even the most basic details.

Compounding this is the fact that there are many layers of interaction taking place in these little engines and each affects the next in an exponential chain of possibilities.
It's pretty accepted that there are many ways to skin the same cat and one persons timing numbers for instance may only work well with a particular recipe that the complexities of which may defy written description short of a novel.
That and the lack of standard terminology leads to a lot of confusion.
There are some general 'rules' and guidelines that will lead to a solid port job but there are always exceptions and what works on one model saw may be detrimental to another.
For me a typical one example for 70ish cc saws and above (including the 372) is timing/opening numbers of 100 ex, 120 trans and 80 int. Hard to go really wrong there on most saws but still...

Having previous experience grinding/porting is a good thing that certainly puts you ahead of the game but unfortunately saws seem to be their own animal and don't cross over well with their larger, often piped cousins.
At one point I think the most difficult thing to get over is unlearning all the assumptions that dirtbike/outboard/whatever experience brings that has surprisingly little to offer on saws and often leads down the path to ruining a cylinder.
Most of my previous porting was on 4 stroke stuff so while saws were (and still are) a big learning curve, I actually think it wasn't as bad because it was easier to accept the difference.

These engines seem to defy a lot of long standing beliefs, an example is that from everything I've seen/experienced, even relatively high comp (2-250psi) woods ports don't require anything more than 87 pump gas (ron + mon divided by 2).
I've never seen compression/fuel related detonation damage on a saw that wasn't caused by bad/old/water polluted gas, certainly not on anything I own.



Aftermarket p&c's are simply a crap shoot, there are good ones and bad ones and no consistency, at least for any length of time (Meteor pistons seem to be an exception), one batch of cylinders by a particular manufacturer may be great and the next junk. Buy a good supply quickly when you find good ones for a good deal.

Plating quality in particular is notoriously difficult to quantify and often varies hugely from one otherwise identical cylinder to another.
And BTW chrome isn't always bad for grinding and nikasil isn't always good...
Meteor and a while back Tecomec is/was generally a cut above but I've seen some real crap from both too. And the prices can be upwards of Oem.

Hyway and Cross seem to be the next best tier these days but still can be sketchy. And still not cheap considering the relative quality IMHO.
The physical layout (port shapes, timing, ect), is a common problem for many but seemingly Meteor in particular, where a cylinder for one model is a virtual clone of oem and for a different one is so far off it's like a cruel joke.
And then there's the casting and machining flaws and crazy beveling (if there's any at all)...
And on and on...
 
Lots to comment on but only time to bring up one huge variable here right now....

Exhaust system....

Motocross bikes and race saws use expansion chamber style exhaust...

That exhaust will easily add 40% more power when matched correctly.... I'm not interested in using one on my work saws...
But...

The exhaust system plays a HUGE role in cylinder pressure evacuation and thus RADICALLY effects necessary blowdown time between exhaust and transfer port opening...

One set of port numbers with one exhaust arrangement may be magic with someone's modded muffler.. and be garbage with another....

You have to pick your exhaust mod desired... Stick to it... And build to it...
 
Not saying you're wrong but you're really over simplifying it.
As much as discussion is good and leads to fresh ideas, it's also good to do your homework and build from a basis that has been established by the experience of countless people that is exhaustively documented here and other sites.
I realize it's a daunting task to ferret out the good info from all the garbage but the info is indeed out there for the taking.

People with many years of experience who were once a wealth of knowledge here get burned out repeating the same info year after year, only to be second guessed by the never ending latest batch of semi enlightened newbs then wanting to be spoon fed exhaustive explanations/justifications to even the most basic details.

Compounding this is the fact that there are many layers of interaction taking place in these little engines and each affects the next in an exponential chain of possibilities.
It's pretty accepted that there are many ways to skin the same cat and one persons timing numbers for instance may only work well with a particular recipe that the complexities of which may defy written description short of a novel.
That and the lack of standard terminology leads to a lot of confusion.
There are some general 'rules' and guidelines that will lead to a solid port job but there are always exceptions and what works on one model saw may be detrimental to another.
For me a typical one example for 70ish cc saws and above (including the 372) is timing/opening numbers of 100 ex, 120 trans and 80 int. Hard to go really wrong there on most saws but still...

Having previous experience grinding/porting is a good thing that certainly puts you ahead of the game but unfortunately saws seem to be their own animal and don't cross over well with their larger, often piped cousins.
At one point I think the most difficult thing to get over is unlearning all the assumptions that dirtbike/outboard/whatever experience brings that has surprisingly little to offer on saws and often leads down the path to ruining a cylinder.
Most of my previous porting was on 4 stroke stuff so while saws were (and still are) a big learning curve, I actually think it wasn't as bad because it was easier to accept the difference.

These engines seem to defy a lot of long standing beliefs, an example is that from everything I've seen/experienced, even relatively high comp (2-250psi) woods ports don't require anything more than 87 pump gas (ron + mon divided by 2).
I've never seen compression/fuel related detonation damage on a saw that wasn't caused by bad/old/water polluted gas, certainly not on anything I own.



Aftermarket p&c's are simply a crap shoot, there are good ones and bad ones and no consistency, at least for any length of time (Meteor pistons seem to be an exception), one batch of cylinders by a particular manufacturer may be great and the next junk. Buy a good supply quickly when you find good ones for a good deal.

Plating quality in particular is notoriously difficult to quantify and often varies hugely from one otherwise identical cylinder to another.
And BTW chrome isn't always bad for grinding and nikasil isn't always good...
Meteor and a while back Tecomec is/was generally a cut above but I've seen some real crap from both too. And the prices can be upwards of Oem.

Hyway and Cross seem to be the next best tier these days but still can be sketchy. And still not cheap considering the relative quality IMHO.
The physical layout (port shapes, timing, ect), is a common problem for many but seemingly Meteor in particular, where a cylinder for one model is a virtual clone of oem and for a different one is so far off it's like a cruel joke.
And then there's the casting and machining flaws and crazy beveling (if there's any at all)...
And on and on...


You have a lot of venom in your words there wcorey....

I have put pro riders on top of pro podiums in everything from flattrack to arenacross to sand hill drag racing... Owned Dyno shops and have done R&D of everything from custom pistons / exhaust / fuel injection systems...

But not yet saws....

And if it irritates you that I come to a public forum , especially hosted for this precise topic, and wish to engage in a current human exchange with willing participants...
You can take the phrase of "semi enlightened newbs" and all your reference to Saw God's gone dark.. put it on a 30" bar and stick it up your ass ....

You think your almighty slumber has been disturbed by unworthy mortals seeking enlightenment?!

It's a public forum... Participation is voluntary... Look away if you don't like it... Simple as that... Who is such an ass as to then take the time to pen condescending words to people with similar interests having a pleasant exchange?!?
 
Gee, I guess a little ‘venom’ begets a nuclear explosion, you’ll fit right in here, lol.
Touchy subject, I know, it seems I hit a nerve.
Was just trying to inject a bit of reality, didn’t mean to come off as a total ****, guess I failed there...

I’ll go slither back under my rock now and await the great revelations from out of harms way.
 
Interesting you would say that. The research and conversations I've had with people on the subject suggest the opposite. Bump in compression, added intake, and a lighter piston. I generally hear it'll make a strong saw without any port work done.

I personally have not done the 268 mod myself as of yet.
For someone who wants to have a machinist turn a pop-up piston , they can be a great mod for a bit of power. But when your porting a few saws a week it's also easy to see the power that you can get out of a 372 with the base and squish band cut
 
Gee, I guess a little ‘venom’ begets a nuclear explosion, you’ll fit right in here, lol.
Touchy subject, I know, it seems I hit a nerve.
Was just trying to inject a bit of reality, didn’t mean to come off as a total ****, guess I failed there...

I’ll go slither back under my rock now and await the great revelations from out of harms way.
I saw nothing but truth in your words sir. It seems some feel that they have something to prove. That's twice today I've seen that from two different individuals.
 
You have a lot of venom in your words there wcorey....

I have put pro riders on top of pro podiums in everything from flattrack to arenacross to sand hill drag racing... Owned Dyno shops and have done R&D of everything from custom pistons / exhaust / fuel injection systems...

But not yet saws....

And if it irritates you that I come to a public forum , especially hosted for this precise topic, and wish to engage in a current human exchange with willing participants...
You can take the phrase of "semi enlightened newbs" and all your reference to Saw God's gone dark.. put it on a 30" bar and stick it up your ass ....

You think your almighty slumber has been disturbed by unworthy mortals seeking enlightenment?!

It's a public forum... Participation is voluntary... Look away if you don't like it... Simple as that... Who is such an ass as to then take the time to pen condescending words to people with similar interests having a pleasant exchange?!?

I swear mate your are the funniest bastard I have ever come across on a forum. Forums can be great but they are political as all hell. The theory is because we are new here so we don't know anything. It always seems that way which is unfortunate. We might get lucky here and start something new or this section remains as it was, which before tappermike come along was dead with hardly anyone posting anything.

If you come on here an ask for a simple recipe to get yourself going you would never get a response for all of the reasons wcory was good enough to inform us of. In all truth I have never worked out how to get over that barrier. It was the same on the long range forum except for me the shoe was on the other foot. I was offering help not asking for it. Yet offing too much help become a problem for some as well.

All I know is there are a percentage of us who enjoy sharing and helping and we should just continue doing what we do for the benefit of others like us who come along long after we have gone.

You build your mid range monster I let me know how you got on. I hope it tears through wood like a banshee and you can post your video to prove your point as will I.
 
I swear mate your are the funniest bastard I have ever come across on a forum. Forums can be great but they are political as all hell. The theory is because we are new here so we don't know anything. It always seems that way which is unfortunate. We might get lucky here and start something new or this section remains as it was, which before tappermike come along was dead with hardly anyone posting anything.

If you come on here an ask for a simple recipe to get yourself going you would never get a response for all of the reasons wcory was good enough to inform us of. In all truth I have never worked out how to get over that barrier. It was the same on the long range forum except for me the shoe was on the other foot. I was offering help not asking for it. Yet offing too much help become a problem for some as well.

All I know is there are a percentage of us who enjoy sharing and helping and we should just continue doing what we do for the benefit of others like us who come along long after we have gone.

You build your mid range monster I let me know how you got on. I hope it tears through wood like a banshee and you can post your video to prove your point as will I.
I know for a FACT there are people here who would share what they know, including numbers, through private message. One of them has posted on this thread. The trouble is, you have to put in the most minimal of effort to develop some rapport here. Get in on some threads, even if it's not in the technical forums. The guys that you want the info from at the minimum have put in some effort to gain that knowledge and probably at least supplement their income with it. For all they know you want to charge 15% less than they do for a port job and have them sitting on their thumbs(I'm not saying this is what I believe, but there's been a turd or two in this punch bowl). Beleive me, if there hadn't been the chest beating in this thread (maybe because you're new and felt the need?) you probably would have had a private message or two by now. Heck, maybe you already have. There are some real good dudes here.
 
I know for a FACT there are people here who would share what they know, including numbers, through private message. One of them has posted on this thread. The trouble is, you have to put in the most minimal of effort to develop some rapport here. Get in on some threads, even if it's not in the technical forums. The guys that you want the info from at the minimum have put in some effort to gain that knowledge and probably at least supplement their income with it. For all they know you want to charge 15% less than they do for a port job and have them sitting on their thumbs(I'm not saying this is what I believe, but there's been a turd or two in this punch bowl). Beleive me, if there hadn't been the chest beating in this thread (maybe because you're new and felt the need?) you probably would have had a private message or two by now. Heck, maybe you already have. There are some real good dudes here.

I appreciate your reply and have no doubt there are good guys here. It’s the culture of forums that always develops that bothers me.

I’m in New Zealand I’m no threat to anyone. A forum is a social thing you join to share and learn I would have thought. I get that pro tuners don’t want to share and respect that but what’s to stop the rest of us?

I know what I’m like and I will crack this saw. I’m all but there. I think for the good of others like me it would be a good thing to post all the detail of what I did when I do. Maybe then others like me won’t even need to ask the question. Maybe that will be a good thing.
 
You have a lot of venom in your words there wcorey....

I have put pro riders on top of pro podiums in everything from flattrack to arenacross to sand hill drag racing... Owned Dyno shops and have done R&D of everything from custom pistons / exhaust / fuel injection systems...

But not yet saws....

And if it irritates you that I come to a public forum , especially hosted for this precise topic, and wish to engage in a current human exchange with willing participants...
You can take the phrase of "semi enlightened newbs" and all your reference to Saw God's gone dark.. put it on a 30" bar and stick it up your ass ....

You think your almighty slumber has been disturbed by unworthy mortals seeking enlightenment?!

It's a public forum... Participation is voluntary... Look away if you don't like it... Simple as that... Who is such an ass as to then take the time to pen condescending words to people with similar interests having a pleasant exchange?!?
I think you mistakenly took Bill's post as being a little hasty. But he's pretty accurate on all accounts, and is a well respected member on a few forums. And gave a good general set of timing numbers that work well in most 70cc saws. You're response, in fact, is the very reason my most guys don't come to this site to give advice.
I gave my advice on the 268 popup based on my own experience, not on something I read here or elsewhere. My experience is largely based on saws rather than bikes, though. Which, given the timing duration numbers mentioned earlier, clearly isn't the case with everyone. 180° of exhaust duration on a muffler 372 would maybe be ok on a 8x8 cant saw.
Let alone the mention of a saw with 200° of exhaust duration.
It was also mentioned before that most things we've learned about motorcycle tuning can be thrown out the door when it comes to saws. They're slightly more similar to a saw that has a pipe on it, but with a muffler there's very little in common.
 
Wow... The inner crowd of saw supremist circle jerkers are all going to have hands too cramped to fire their saws if they don't slow down on all the back patting and secret decoder ring code checking ...

As a matter of fact... dirt bikes have a lot more complexity to their engines and their power delivery nature than does a saw.... A lot..

On/off switch / WOT and Idle use 2 strokes with 2 whole jetting circuits aren't the deepest jungle in the engineering world...

And also.... Are we thinking these things are tools we clear tracks and cut firewood with... Or are they a parallel to a Viking Sword/ Phallic symbol of alpha male dominance?!?

Grow up you guys.... Or go stroke egos in another thread... I shall have no Saw God before me....lol...and Hahahahahahahahahahahahahahahahaha....

So... That out of the way...

Some saw specific tuning parameters....

Crankcase charging... Work saw, not expansion chamber equipped....

If you have an expansion chamber setup you can make good use of more crankcase volume... I'm going to use the term "pipe" interchangeably with expansion chamber" for ease of typing...
The negative wave generated vacuum from the pipe makes it valuable to have more crankcase volume because it is not only strong enough to evacuate the burnt charge, it also pulls plenty of fresh charge through the transfer ports (more to the pipe function story , but not now).... So you don't want to have such a limited crankcase volume that the pipe would end up fighting pulling more fresh charge against the case vacuum it's actually creating by pulling through the transfers...

Now... A bigger case volume ... Pulled to a level of vacuum by the pipe before the piston even begins up the cylinder... Is going to create a longer / stronger vacuum signal to the carb/ intake tract.....

Ok... Now let's sadly drop the magical pipe.... And go to "work saw muffler"

The muffler doesn't have ANY of the pulse charging sonic supercharger effect to it.,.. it's not even neutral... It's negative....

By direct reflection and pressure chambers, there is a lot of restriction to escaping exhaust gasses... And no vacuum generated...

So now there isn't a "pull" assisting charge flow through the transfer ports.... It's only the push from the downward piston motion derived crankcase compression... Do you think cavernous sewer pipe volume ports and bigger case volumes are going to be helping here?? I'm talking volumes , not port timing...

Velocity is where momentum energy has a exponent on it... Double a bullets weight and you have double the energy... Double the speed and you have 4 times the energy....

What this means is a fast moving air flow column works with train-like momentum.... Within the limits of actual pumping losses... You can make good power advantage by having an intake port that holds charge velocity and keeps filling the case after the piston begins compressing the charge... Preventing reversion... Until the piston skirt closes the the port....

More crankcase charge means there will be a better push through the transfers ... More effective transfer of compressive force when the medium you are compressing is denser....

That's a decent highlight on the different dynamics at play between "Piped" and "Mufflered" 2 strokes...

Soooooooo....

Since the muffler is all negative influence in a performance minded work saw.... And since cylinder pressure evacuation is important to time before exposing transfer ports ... You don't want your low pressure crankcase charge to fight against exhaust gas pressure , maybe even pushing down the transfer port and further polluting the fresh charge, now do you??!!??

So... Why wouldn't you want to take that uncertainty and all negative Muffler .... And do what you can to take it to LESS negative effect?!

Now you have a chance at using less exhaust port timing to the same amount of desired increased amount of exhaust flow.... It will also mean you could use less blowdown and more transfer port timing for stronger mid range torque....

There are a multitude of ways to "port" a muffler... But I have stated prior that I prefer to make mine a version of a short glasspack silencer... Although I have made a few with better flowpaths that guide airflow and diminish the direct sound reflection .... And they worked better than stock also...

Anyways... That summarizes my current musings on saw style 2 stroke differences to the piped dirt bike differences ...

I'm new to heightened interest in having fun with a bit higher output from my saws... Addictive hobby, engines .... But I am a long ways from newbie to 2 and 4 stroke performance.....

Always enjoy sharing/ exchanging info with other gearheads ....

Came in for some comraderie and some input/help to get up to speed on quality vs folley on parts...

Not at all looking for a testosterone driven territorial pissing match....

Why bother with a forum or thread if you find it so abrasive?!?

I'm not begging for any help... Nobody owes me any information.... All voluntary.... No forced participation.... For amusement and education .... Did I mention voluntary??
 
Wow... The inner crowd of saw supremist circle jerkers are all going to have hands too cramped to fire their saws if they don't slow down on all the back patting and secret decoder ring code checking ...

As a matter of fact... dirt bikes have a lot more complexity to their engines and their power delivery nature than does a saw.... A lot..

On/off switch / WOT and Idle use 2 strokes with 2 whole jetting circuits aren't the deepest jungle in the engineering world...

And also.... Are we thinking these things are tools we clear tracks and cut firewood with... Or are they a parallel to a Viking Sword/ Phallic symbol of alpha male dominance?!?

Grow up you guys.... Or go stroke egos in another thread... I shall have no Saw God before me....lol...and Hahahahahahahahahahahahahahahahaha....

So... That out of the way...

Some saw specific tuning parameters....

Crankcase charging... Work saw, not expansion chamber equipped....

If you have an expansion chamber setup you can make good use of more crankcase volume... I'm going to use the term "pipe" interchangeably with expansion chamber" for ease of typing...
The negative wave generated vacuum from the pipe makes it valuable to have more crankcase volume because it is not only strong enough to evacuate the burnt charge, it also pulls plenty of fresh charge through the transfer ports (more to the pipe function story , but not now).... So you don't want to have such a limited crankcase volume that the pipe would end up fighting pulling more fresh charge against the case vacuum it's actually creating by pulling through the transfers...

Now... A bigger case volume ... Pulled to a level of vacuum by the pipe before the piston even begins up the cylinder... Is going to create a longer / stronger vacuum signal to the carb/ intake tract.....

Ok... Now let's sadly drop the magical pipe.... And go to "work saw muffler"

The muffler doesn't have ANY of the pulse charging sonic supercharger effect to it.,.. it's not even neutral... It's negative....

By direct reflection and pressure chambers, there is a lot of restriction to escaping exhaust gasses... And no vacuum generated...

So now there isn't a "pull" assisting charge flow through the transfer ports.... It's only the push from the downward piston motion derived crankcase compression... Do you think cavernous sewer pipe volume ports and bigger case volumes are going to be helping here?? I'm talking volumes , not port timing...

Velocity is where momentum energy has a exponent on it... Double a bullets weight and you have double the energy... Double the speed and you have 4 times the energy....

What this means is a fast moving air flow column works with train-like momentum.... Within the limits of actual pumping losses... You can make good power advantage by having an intake port that holds charge velocity and keeps filling the case after the piston begins compressing the charge... Preventing reversion... Until the piston skirt closes the the port....

More crankcase charge means there will be a better push through the transfers ... More effective transfer of compressive force when the medium you are compressing is denser....

That's a decent highlight on the different dynamics at play between "Piped" and "Mufflered" 2 strokes...

Soooooooo....

Since the muffler is all negative influence in a performance minded work saw.... And since cylinder pressure evacuation is important to time before exposing transfer ports ... You don't want your low pressure crankcase charge to fight against exhaust gas pressure , maybe even pushing down the transfer port and further polluting the fresh charge, now do you??!!??

So... Why wouldn't you want to take that uncertainty and all negative Muffler .... And do what you can to take it to LESS negative effect?!

Now you have a chance at using less exhaust port timing to the same amount of desired increased amount of exhaust flow.... It will also mean you could use less blowdown and more transfer port timing for stronger mid range torque....

There are a multitude of ways to "port" a muffler... But I have stated prior that I prefer to make mine a version of a short glasspack silencer... Although I have made a few with better flowpaths that guide airflow and diminish the direct sound reflection .... And they worked better than stock also...

Anyways... That summarizes my current musings on saw style 2 stroke differences to the piped dirt bike differences ...

I'm new to heightened interest in having fun with a bit higher output from my saws... Addictive hobby, engines .... But I am a long ways from newbie to 2 and 4 stroke performance.....

Always enjoy sharing/ exchanging info with other gearheads ....

Came in for some comraderie and some input/help to get up to speed on quality vs folley on parts...

Not at all looking for a testosterone driven territorial pissing match....

Why bother with a forum or thread if you find it so abrasive?!?

I'm not begging for any help... Nobody owes me any information.... All voluntary.... No forced participation.... For amusement and education .... Did I mention voluntary??
Does all of that come with a mic drop?

Seriously?
 
Welp, I'm out. @wcorey is out.
You've got @blsnelling , @drf255, and @crabby cooter

Best of luck finding any voluntary information lmao

Wow! Only 5 people in the world can build a saw. I really thought there were more than that. So all the other guys don't count? You guys are it? The ego in this room defies belief! Any wonder this section is dead as a door nail.
 

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