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post #1 of 22 Old 09-07-2010, 12:08 PM Thread Starter
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Port & Polish . . . .

I just thought this might be a good thread to start because I don't think we've ever touched on this topic in any kind of detail. I am SURE NOT an expert on this topic (which is why I am posting it) so don't accuse me of thinking that I am.

I will share what I think I know and it is all very general, so if you have some experience or knowledge to share please chime in, and set me straight where I may have been wrong so someone doesn't take bad info away.

If you ever have your saw ported, make sure you choose someone who has a lot of experience. You don't just send your powerhead to a guy that says he'll port and polish, because for example if he doesn't ask you how you'll use your saw you already know not to send it to him. The P&P for a milling saw must be done differently than for a firewood saw to get the most efficient combustion and exhaust, and to "put" the power band in the right place on the chart.

I'm sure it isn't phrased well, but it's to do with the amount of metal and where they take it out and how much "shelf" (?) or whatever they leave. It's a highly technical field and you don't want to trust your saw to just any of them.

For those who may not be familiar with what porting and or polishing means, "porting" is removing some amount of metal mainly from around the intake & exhaust valves I think - and "polishing" is just that, the polishing of the inside of the head chamber to smooth the relatively rough factory castings to decrease the friction of the airflow across the surface of the metal. They take this to extremes in race engines everything from top fuel dragsters down to chainsaws - and it is an art form.

"Woods" porting simply means that the degree of modifications are enough to greatly enhance the performance of the saw, but still moderate enough that the life and reliability of the engine are not dramatically reduced, as they are in an extreme race application. In fact, my understanding is that when that perfect balance between the two is achieved, a good woods ported job will actually extend the life of the saw if proper routine maintenance is performed.

I did the muffler mod on my 372XP and that alone woke the saw up like I couldn't believe. I talked to John at Walkers in Nanaimo a couple years ago and he told me how to set the carb. Muffler mods an also be part of a woods porting job and usually are because there is now more much more exhaust to get rid of.


I'm really wanting to get a woods job on my 395's & 372. Anyone ever have theirs done and if so who did it? Were you happy?







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post #2 of 22 Old 09-07-2010, 12:21 PM
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Quote:
Originally Posted by TexasTimbers View Post
I just thought this might be a good thread to start because I don't think we've ever touched on this topic in any kind of detail. I am SURE NOT an expert on this topic (which is why I am posting it) so don't accuse me of thinking that I am.

I will share what I think I know and it is all very general, so if you have some experience or knowledge to share please chime in, and set me straight where I may have been wrong so someone doesn't take bad info away.

If you ever have your saw ported, make sure you choose someone who has a lot of experience. You don't just send your powerhead to a guy that says he'll port and polish, because for example if he doesn't ask you how you'll use your saw you already know not to send it to him. The P&P for a milling saw must be done differently than for a firewood saw to get the most efficient combustion and exhaust, and to "put" the power band in the right place on the chart.

I'm sure it isn't phrased well, but it's to do with the amount of metal and where they take it out and how much "shelf" (?) or whatever they leave. It's a highly technical field and you don't want to trust your saw to just any of them.

For those who may not be familiar with what porting and or polishing means, "porting" is removing some amount of metal mainly from around the intake & exhaust valves I think - and "polishing" is just that, the polishing of the inside of the head chamber to smooth the relatively rough factory castings to decrease the friction of the airflow across the surface of the metal. They take this to extremes in race engines everything from top fuel dragsters down to chainsaws - and it is an art form.

"Woods" porting simply means that the degree of modifications are enough to greatly enhance the performance of the saw, but still moderate enough that the life and reliability of the engine are not dramatically reduced, as they are in an extreme race application. In fact, my understanding is that when that perfect balance between the two is achieved, a good woods ported job will actually extend the life of the saw if proper routine maintenance is performed.

I did the muffler mod on my 372XP and that alone woke the saw up like I couldn't believe. I talked to John at Walkers in Nanaimo a couple years ago and he told me how to set the carb. Muffler mods an also be part of a woods porting job and usually are because there is now more much more exhaust to get rid of.


I'm really wanting to get a woods job on my 395's & 372. Anyone ever have theirs done and if so who did it? Were you happy?







.
I used to port out my McCulloch Mc10 and mc20 mc30 motor's that i raced with. I would square the round port holes. which had 3 port hole's . And run 3 cabarator's on each. with crankcase stuffer's and other good mod's. The good old day's. Also ran alcohal with castor oil . Drilled out the holes in the carb's to about 3 size's bigger. I had the drill size's . Don't know them now. they were using the number drill's . Sure did run good. I didn't need to polish the cylinder I would put in a new set of ring's after each day. And just let it suck in some ajax to seat in the ring's. Sure did have Compression . Thanks for reading
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post #3 of 22 Old 09-07-2010, 12:42 PM
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You have me convinced! I say you deserve it.
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post #4 of 22 Old 09-07-2010, 03:33 PM
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I did the muffler mod on my 372XP and that alone woke the saw up like I couldn't believe.
OK, so I'm going to ask, 'what's a muffler modification'?
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post #5 of 22 Old 09-08-2010, 10:09 AM Thread Starter
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OK, so I'm going to ask, 'what's a muffler modification'?
Enlarging or adding exhaust ports to the muffler of most saws (and many other small engines especially 2-stroke) will give it more power. But that's only part of the mod. You have to adjust the carburetor after that also or you could burn the saw up.

If anyone actually wants to do it I'll dig up the procedure I used to do my 372XP 5 years ago that is still running like a scalded dog. It's the same for most saws. If you have one of the newer green saws it will feel like you traded it in for the next larger cc class, depending on the particular model.

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post #6 of 22 Old 09-08-2010, 12:31 PM
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I have a Stihl 036 Pro that I was going to muffler mod, but I think its compression is getting low, gotta check. Been thinking if it needs a rebuild may be cool to get a woods port too. Muffler modded a homelite 43cc and it woke up nicely, actually had carb adjustments. It and a pile of 8 others in various disrepair are the closest thing I have to practice modding a 50cc race bike, Yamaha YSR50, I picked up recently.

"Say hello to my little friend" Macie Clark, Christmas 2010

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post #7 of 22 Old 09-09-2010, 12:30 PM
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Originally Posted by TexasTimbers View Post
Enlarging or adding exhaust ports to the muffler of most saws (and many other small engines especially 2-stroke) will give it more power. But that's only part of the mod. You have to adjust the carburetor after that also or you could burn the saw up.
This is purely academic for me now. If I attempted it or had someone else do it for me, I'd end up with a screwed up saw. That's the way my luck goes. But if a increase can be had, why don't saws straight from the manufacturer come modified this way? Is there an increased noise level thus being the reason?
I had lost a screw holding the muffler in place at one time, and the muffler became loose and very loud. I corrected the problem shortly after I noticed it. Would this have acted in the same manner as a muffler modification in the fact that it was releasing the back pressure faster, causing the saw to run hotter? If so, this would help explain mu recent need to have an "inner seal" replaced because it was burned up?
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post #8 of 22 Old 09-09-2010, 12:38 PM
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I have been looking everywhere on this thread for a comment by Tim The Toolman. I cannot find it. I had never dreamed that people would port and polish a chain saw.

George
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post #9 of 22 Old 09-09-2010, 02:49 PM Thread Starter
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Originally Posted by djg
. . . But if a increase can be had, why don't saws straight from the manufacturer come modified this way? Is there an increased noise level thus being the reason?
That's most likely one reason because it does make them louder, but there are several more reasons mostly being engineering/manufacturing/liability related. There's nearly an infinite number of things you can do to increase performance in an internal combustion engine. Manufacturer's identify a market and build the engine to do the job acceptably but not more. I think the main reason may be because manufacturers have to build saws for all regions i.e. climates, elevations, and temperatures. The stock saws are probably built to cover the widest spectrum of applications to give reliable performance and longevity. I'm sure I don't know all the reasons though.


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Originally Posted by djg
I had lost a screw holding the muffler in place at one time, and the muffler became loose and very loud. I corrected the problem shortly after I noticed it. Would this have acted in the same manner as a muffler modification in the fact that it was releasing the back pressure faster, causing the saw to run hotter?
No, if you had run it long enough like that it would have warped your valves. Once the saw is shut off and the cold air (cold even in summer, relative to internal engine temps) is able to migrate directly into the engine between the muffler and block because of a bad gasket it will reach those extremely hot valves too soon and they will warp. With a good gasket, ambient air must migrate through the muffler first, but the hot air trapped inside the muffler acts as a buffer zone and allows the valves to cool back down slowly so that they don't warp.


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Originally Posted by djg
If so, this would help explain mu recent need to have an "inner seal" replaced because it was burned up?
Maybe. I'm not sure what you mean by "inner seal" though.



There's all kinds of things to consider when modifying an engine, most of which a simple 2-stroke muffler mod doesn't entail. As long as the fuel mixture is set correctly after the mod, and as long as the combined surface area of exhaust ports on the outside of the muffler do not exceed roughly 80% of the surface area of the exhaust port itself (the one between the block and the muffler) then you're pretty much set to go. Some of the chainsaw wizards who do it for a living will also consider other factors such as “Pop-Off” - which is the psi at which the fuel line will pop off of its barb on carburetor. DIYers have been getting along fine for years though without doing that. That's usually only part of more complex mods in addition to a muff mod.

Unless you're lucky enough to get to apprentice under a wizard, it can take years to master overarching complex mods on even one or two types of chainsaw engines, much less a wide variety of engines and applications. But a simple muffler mod is not a big deal on most saws.






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post #10 of 22 Old 09-09-2010, 06:39 PM
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Almost made a big mistake. Based on the title I thought we were going to discuss having polish sausage with port wine. (OK, I'll admit that was bad and offered nothing to the discussion. Just couldn't resist. Carry on gentlemen)
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post #11 of 22 Old 09-09-2010, 07:17 PM
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The stock saws are probably built to cover the widest spectrum of applications to give reliable performance and longevity.



Maybe. I'm not sure what you mean by "inner seal" though.
OK, that makes sense.

I really don't know what I mean by "inner seal" either. That's what they told me the finally replaced to get the saw running. Something to do supposedly with the gas/air mixture not being correct due to this seal.

I think if I ever torn into a saw, a lot of more of this would make sense. Maybe I'll run into a cheap saw that needs repair and try to fix it. It would be a good education.

Thanks for your lengthy response, but don't take offense if I don't go out and get a mod done on my saw, right away. I have a pet peeve about people asking for advice, and then after a lot of effort of someone else (you) to explain, turn around and ignore the advice. I did say it was academic at this point. I'm happy with the way my saw is running now. Of course, if I had it done, I'd probably kick my self for not doing it sooner.

Thanks
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post #12 of 22 Old 09-09-2010, 08:12 PM Thread Starter
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. . . don't take offense if I don't go out and get a mod done on my saw, right away.
Oh no way. I just wanted to get a discussion going and see what kind of experience members had in this area. I have some saws myself that I won't mod because it doesn't make sense for all saws in all applications.



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Almost made a big mistake. Based on the title I thought we were going to discuss having polish sausage with port wine.
It's never a mistake to bring up port wine or Polish sausage. I love Polish sausage hot off the grill on french sourdough with lots of sauerkraut and mustard. In the port category my favorite is Sandeman Ruby. Never had them together but thanks for the idea.




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post #13 of 22 Old 09-10-2010, 08:19 AM
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Originally Posted by djg View Post
This is purely academic for me now. If I attempted it or had someone else do it for me, I'd end up with a screwed up saw. That's the way my luck goes. But if a increase can be had, why don't saws straight from the manufacturer come modified this way? Is there an increased noise level thus being the reason?
I had lost a screw holding the muffler in place at one time, and the muffler became loose and very loud. I corrected the problem shortly after I noticed it. Would this have acted in the same manner as a muffler modification in the fact that it was releasing the back pressure faster, causing the saw to run hotter? If so, this would help explain mu recent need to have an "inner seal" replaced because it was burned up?
muffler does a few things. Make's back preasure so the saw run's better. and than pull's heat from the port's. Their is in the muffler a item they call spark arrester. This keep's exhaust spark's from comming out and maybe causing a fire. Now if you know this isn't going to happen you can take this out. Now this help's a lot. But i am not telling you to do this. I have taken mine out. What happen's is this dam thing get's oil build up and close's down the exhouat and make's the unit all most powerless You will know when this happen's. All of out of the air you find the unit not doing what it used to do. Now you go looking. And find out this thing is almost pluged up. If you have been at the race's Guess what all muffler's have been modified. Here the lowed noise not stock any more. But you have to have a muffler of some kind. Unit lill burn up the pistion and ring's real fast. 2 cycle need's this. Now a 4 cycle won't do it as fast. Because the piston has oil rings on piston and help's keep the piston lubed. 2 cycle gas and oil mix Most burn's up . so you need a muffler to pull heat away . long enough story thanks for reading
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post #14 of 22 Old 09-14-2010, 08:31 AM
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There's all kinds of things to consider when modifying an engine, most of which a simple 2-stroke muffler mod doesn't entail. As long as the fuel mixture is set correctly after the mod, and as long as the combined surface area of exhaust ports on the outside of the muffler do not exceed roughly 80% of the surface area of the exhaust port itself (the one between the block and the muffler) then you're pretty much set to go.

.
i am starting a new thread off this quote so as not to get off topic here.
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post #15 of 22 Old 09-14-2010, 08:40 AM
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carb adjustments after muff-mod

this quote pulled from the port/polish thread:

Quote:
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There's all kinds of things to consider when modifying an engine, most of which a simple 2-stroke muffler mod doesn't entail. As long as the fuel mixture is set correctly after the mod, and as long as the combined surface area of exhaust ports on the outside of the muffler do not exceed roughly 80% of the surface area of the exhaust port itself (the one between the block and the muffler) then you're pretty much set to go.

.
i am more than a little fuzzy on this one-
how exactly should the carb be adjusted after a muff-mod?

i have been told the mixture should be set rich in the first place for milling, which i 'get'.

but lets assume i did just port my muffler to 80% of the cylinder exhaust port area, now what? is it a matter of adjusting the H and L screws, or is it more involved?

also, while we are at the "DIY" stage of saw mods, can anyone clearly explain how to remove the limiting screws on a carb?

thanks!

oh and here's the fruits of a couple hours labor this past friday. pin oak, roughly 66" long, 36" at the widest.
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post #16 of 22 Old 09-14-2010, 09:24 AM
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Can't help you with your question. I'm just watching and learning. My question about your log, and this is NOT criticism, just for learning purposes in case I ever get a proper saw. Where you going to make live edge table tops from all that lumber? If not, I curious why you flitch? sawed the whole log. Wouldn't it have been better to take a few flitches off opposite sides and then cant it up and pull narrower boards? Looks like the center has a lot of stress cracks? in it. I thought this would cause some warpage in your pile. Don't really know for sure, you're farther along than I am and have more experience.
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post #17 of 22 Old 09-14-2010, 10:29 AM Thread Starter
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i am starting a new thread off this quote so as not to get off topic here.
How could it be "off topic" if it's "off this quote"?
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post #18 of 22 Old 09-14-2010, 11:12 AM Thread Starter
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this quote pulled from the port/polish thread:
I merged them so we don't have two concurrent threads about the same thing - I have a hard enough time keeping up with one thread per topic!


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i am more than a little fuzzy on this one-
how exactly should the carb be adjusted after a muff-mod?

i have been told the mixture should be set rich in the first place for milling, which i 'get'.

but lets assume i did just port my muffler to 80% of the cylinder exhaust port area, now what? is it a matter of adjusting the H and L screws, or is it more involved? . . . .
You can adjust your carb by ear if you don't have a tachometer. This page answers all the questions you have put forth - and make sure to listen to the two audio files and the light bulb should come on.


dj, that particular method of sawing is called boule milling. Nakashima's favorite way to mill a log because it gave him more choices of natural edge material to choose from.




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post #19 of 22 Old 09-14-2010, 02:00 PM
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dj, that particular method of sawing is called boule milling. Nakashima's favorite way to mill a log because it gave him more choices of natural edge material to choose from.
Thanks, that makes sense.
Correct me if I'm wrong, but the few pin oak logs I've seen were pretty plain Jane. Not the nice grain pattern of other red oaks.
Could just be my memory failing.
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post #20 of 22 Old 09-15-2010, 12:28 AM
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Thanks, that makes sense.
Correct me if I'm wrong, but the few pin oak logs I've seen were pretty plain Jane. Not the nice grain pattern of other red oaks.
Could just be my memory failing.
yeah it's a little plain but there is some nice flecking along the quarter sawn edges of the center slabs. those cracks in the center are pretty prominent- the tree was taken down in early june and was sitting around till now without having had the ends sealed. there is also a streak of weird spongy fungus running up the pith. i've never been a fan of red oak, especially for furniture. the guys who let me saw this log up told me it was sugar maple! i took them at their word and didn't even scrutinize the thing before setting up to mill. when we removed that first slab we were all surprised. but, the saw was warmed up and so were we so we just cut it up. No plans for it yet, so we just slabbed it up and we'll see what becomes of it. i have some pics of a couple of the boards, i'll post them when i get them off the camera.

Texas, as far as the off topic/new thread thing, i just didn't want to start down the 'muff-mod/carb tuning' road in the 'port/polish' thread, believe it or not some people get touchy about these things. but i'm glad you merged them, easier for me too. and thanks for that link.
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