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Chainsaw Porting Theory

Moparmyway

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I'm thinking stainless sauce cups from restaurants would make a nice cone.

I'll have to palm one tonight from the place I take my lady.

Joking, I despise thieves. I'm gonna buy some on Amazon.
I am very interested in what you decide to do and the results that you get.

The theory behind what Mike suggested (if I understood him correctly) and what I am trying, is to prevent the exhaust from impacting the front cover, and give it more of a helping hand right out either one of the two openings
 

Motorhead

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I'm thinking stainless sauce cups from restaurants would make a nice cone.

I'll have to palm one tonight from the place I take my lady.

Joking, I despise thieves. I'm gonna buy some on Amazon.
Home lite had what they called a stiffener that was bolted to the exhaust port,It looks like a small cup,They also notched the top of the exhaust port,I have a 410 with that set up,I removed the stiffener one time and lost power so I put it back on.
 

jmssaws

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Do you guys set quads higher or lower than duals? I seem to keep them around the same height as the duals,just wondering what you guys have found.

For instance do you change your transfer numbers much between a 394 to a 395?
 

Redfin

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I am very interested in what you decide to do and the results that you get.

The theory behind what Mike suggested (if I understood him correctly) and what I am trying, is to prevent the exhaust from impacting the front cover, and give it more of a helping hand right out either one of the two openings

Kevin what thread was this in?
 

MustangMike

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Randy, Isn't a lot of it a balance between power, RPMS, torque, longevity, and fuel economy?

In addition to speed in the cut, I would love to see the fuel usage for 2 saws of the same model, ported differently.

IMO, it is all important.
 

junkman

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Randy, Isn't a lot of it a balance between power, RPMS, torque, longevity, and fuel economy?

In addition to speed in the cut, I would love to see the fuel usage for 2 saws of the same model, ported differently.

IMO, it is all important.
You can get gains and economy if you keep the air in longer a wise one told me once .
 

metallic

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The role of the bottom end (crankcase volume) interests me as to how it relates to what type of modifications would work best on the top end. I've searched google until my eyes glaze over and haven't found anything that we could use as a "rule" such as if the crankcase volume is x% of the displacement, then focus on intake timing or exhaust timing, etc. Crankcase volume is easy to determine (pour a measured amount of premix oil into the bottom end..), but then what can we do with that information?
 

Mastermind

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Im always curious to know how u decide what way to go when u run a stock saw , for example this saw needs more intake or higher transfers ? Is it traits that u pick up on from running lots of saws and studying them and a lot of trial and error ... Lower exhaust makes sense to me , longer stroke build more compression ect

Trial and error is 60% of what I've learned.......stealing Treemonkey's ideas account for the rest. :)

I'd say its about 40% traits from running lots of saws after the 60% of trial and errors

The best way to answer most porting questions is to be saw specific, as what works with one saw does not necessarily work with another saw.
Yes, some theories do apply to all saws, but the best way to see what works is to change one thing, then run the saw.
If you gain, make a note and keep going ........... if you lose, chalk it up, make a note, and dont go further in that one area

Just because Homer Simpson hogs out his lower transferrs does not mean that everyone should do the same thing. Homer might be doing other things to the motor that allow the lowers to respond better to being hogged out

Here is where the rubber meets the road .................the more you know about 2 strokes, the more you realize that you dont know squat about them.
Just when you begin to understand what youre doing, someone will come along and throw an idea at you, which makes you think that what you were origionally thinking about shouldnt or wont work.

Spot on......

So ill be the first to admit i know nothing about non nitro methane running 2 strokes. The little high revving whiny motors im used to porting polishing and tuning, are way different than our larger displacement wood killing ones, and im out of my comfort zone. When porting a large displacement saw like an 084, what sweet spot are you looking for?
Is it just your previous knowledge of past work that lets you know where you are and how far you can go?

I've done about 1000 saws.......maybe more. Some real turds in the bunch.......those turds taught me more than the ones that were great.

1) What does a higher exhaust do?
2) What does a lower intake do?
3) What does a higher intake roof do
4) What does a wider exhaust do?
5) What does a wider intake do?

Easy now big feller......

I am always curious about the use of epoxies, jb weld, etc used to buildup/reconfigure. Does this ever come loose or fall out? Granted I have limited experience with these materials, but seems the heat and vibrations would eventually break this loose.

I've yet to see any come out........but I'm 100% sure that it can. I go way overboard on surface prep.....

What i would like to know is what is different when porting for something like a milling saw vs something like a racing saw or even an every day limbing/cording saw.

Compression makes heat.....heat kills milling saws. Compression can slow down a saw that you want big rpm from too.......

Compression is an easy way to gain torque though........

100% of the problem with ported saws is 99% of the people don't understand them. This is not me being arrogant and assuming I do understand them, just me offering up my view.

With all things in life balance is critical. I personally feel as we become more specialized, our range of success and impact diminishes, however our magnitude of success and impact in a certain specialized area increases.

Applying this to chainsaws, one could compare a race saw, a work saw and a stock saw.

A race saw can't cut timber or firewood, is costly to produce, burns expensive fuel in custom carburetors and operates on the ragged edge failure. Properly built, it is good at making high horsepower and going fast through a cant.

A stock saw, when cared for and maintained, will reliably fall timber and cut firewood for years at a relatively low cost of ownership. These are the machines that will allow a man to make a good living, heat his house, prune his trees, cut wood for a camp-fire. The jack of all trades, master of none.

A work saw occupies the void between a stock saw and a race saw, and can be on either end of the spectrum. One should look back at the legendary saws of the day and understand what it is that makes them apart from their competition. One must also understand the desired application of the saw, and build accordingly. A 5-cube with an exhaust at 105* is going to have high compression and not bat an eye at a ham-fisted operator dogging in a 36" bar. That same 5-cube isn't going to stand a chance against a like model saw with a 95* exhaust running a good chain and 20" bar through 18" wood. It won't turn the RPM, and the operator will still be sawing the face cut while the second saw is moving to the next tree.

It's my opinion that if you aren't trying new things, and figuring out what works for you, and WHY it works for you, you aren't progressing. You may one day realize all that you have missed while following the herd.

Nice post Josh.
 

Keith Gandy

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Trial and error is 60% of what I've learned.......stealing Treemonkey's ideas account for the rest. :)



Spot on......



I've done about 1000 saws.......maybe more. Some real turds in the bunch.......those turds taught me more than the ones that were great.



Easy now big feller......



I've yet to see any come out........but I'm 100% sure that it can. I go way overboard on surface prep.....



Compression makes heat.....heat kills milling saws. Compression can slow down a saw that you want big rpm from too.......

Compression is an easy way to gain torque though........



Nice post Josh.
I want anwsers!! :):neng2kb:
 

Ray Bell

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100% of the problem with ported saws is 99% of the people don't understand them. This is not me being arrogant and assuming I do understand them, just me offering up my view.

With all things in life balance is critical. I personally feel as we become more specialized, our range of success and impact diminishes, however our magnitude of success and impact in a certain specialized area increases.

Applying this to chainsaws, one could compare a race saw, a work saw and a stock saw.

A race saw can't cut timber or firewood, is costly to produce, burns expensive fuel in custom carburetors and operates on the ragged edge failure. Properly built, it is good at making high horsepower and going fast through a cant.

A stock saw, when cared for and maintained, will reliably fall timber and cut firewood for years at a relatively low cost of ownership. These are the machines that will allow a man to make a good living, heat his house, prune his trees, cut wood for a camp-fire. The jack of all trades, master of none.

A work saw occupies the void between a stock saw and a race saw, and can be on either end of the spectrum. One should look back at the legendary saws of the day and understand what it is that makes them apart from their competition. One must also understand the desired application of the saw, and build accordingly. A 5-cube with an exhaust at 105* is going to have high compression and not bat an eye at a ham-fisted operator dogging in a 36" bar. That same 5-cube isn't going to stand a chance against a like model saw with a 95* exhaust running a good chain and 20" bar through 18" wood. It won't turn the RPM, and the operator will still be sawing the face cut while the second saw is moving to the next tree.

It's my opinion that if you aren't trying new things, and figuring out what works for you, and WHY it works for you, you aren't progressing. You may one day realize all that you have missed while following the herd.
So, if I am understanding this correctly maybe the work saw is the stock saw with a few EPA regs eliminated, but not a full blown, ported, go fast saw? Properly maintained they will last as long as the stock saw?
I am a REAL amature compared to most on here. I am a wood turner and although have several saws (mild cad) I use my 372 xt exclusively when bucking or noodling bowl blanks. I don't burn wood, and have no other reason to use a chainsaw except for cutting Woodturning blanks. I will never race, and as much as I would like to eventually attend a gtg because I love to see and hear saws, probably never will.
In any case would it be beneficial to me to have the 372xt woods ported? Would it increase cutting power while maintaining fuel efficiency, reliability, and longevity?
 

redoakneck

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Randy learns from turds?? Me too, when my dogs eats a box of crayons, the turds are really colorful,

Subbed, I'll shut up now, I have no idea wtf makes one run better than another, maybe I'll learn something here, pretty old though and those equations bring back nightmares!!!
 

drf256

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Do you guys set quads higher or lower than duals? I seem to keep them around the same height as the duals,just wondering what you guys have found.

For instance do you change your transfer numbers much between a 394 to a 395?
They're generally set physically lower than a 2 port. Tighter shorter passages. More velocity. Don't need to be as high to fill cylinder.
 

drf256

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Home lite had what they called a stiffener that was bolted to the exhaust port,It looks like a small cup,They also notched the top of the exhaust port,I have a 410 with that set up,I removed the stiffener one time and lost power so I put it back on.
No reason to think we can't get at least some wave reflection back. It will never be a pipe, but it may be better than nothing.
 

Mastermind

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Brilliant thread to start Mr M !!!
My question is based around that thing.. what sets you off in a direction with a cylinder ? Can one be looked over as to how its been designed and that would tell you how it lends its self to work and what the appropriate treatment may be along with how far you want to take things ..OR.. is it Numbers ,numbers Numbers ..first and that can start the brain a ticking. Is there a basic.. GO TO.. start point to build on. :)

I look at what the factory designers gave us first. Then I take the time to try to figure out why they did things the way they did. After all, they have years of R&D to pull from.

Once I understand the design, I can make a decision on which way I want to go.

1) What does a higher exhaust do?
2) What does a lower intake do?
3) What does a higher intake roof do
4) What does a wider exhaust do?
5) What does a wider intake do?

1) Raises the max HP point higher.
2) Not sure what you are asking.....higher number, or higher physically?
3) That depends on where the piston skirt is at tdc, and the size of the intake tract.
4) Same as 1)
5) Again, that depends on whether or not more intake is needed. In some cases it does nothing but make the piston wear faster.
 
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