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I heard one guy ported a chainsaw with only a bench grinder that had 10" wheels on it.
Now that takes some skill.
Now that takes some skill.
Teach me how to port a chainsaw
- Thread starter Trx250r180
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astnmacgto
Carnac The Magnificent
Well I could do it using a toothbrush, a deck screw, a rubber truck strap, and some orange peels! Oh and an angle grinder to set the squish!I heard one guy ported a chainsaw with only a bench grinder that had 10" wheels on it.
Now that takes some skill.
earlthegoat2
ArboristSite Guru
I just bought a Foredom for $130 off of a woodworking site. Played around with a junked 460 cylinder and then researched a little. Read the Jennings 2 stroke modification book. Played around on a junk 044 cylinder.
Mild porting for work saws is very doable. Especially if you are like me and have an extensive metal fabrication background.
Mild porting for work saws is very doable. Especially if you are like me and have an extensive metal fabrication background.
Mild porting is accessible for just about anyone if they can get access to the information, a little patient guidance and practice. Too bad folks treat it like a cross between rocket science, pure f-ing magic and state secrets.
astnmacgto
Carnac The Magnificent
As long as you don't cut too much, I think its pretty easy to turn a running saw into a hard charger, and then into a worthless air pump
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Well I could do it using a toothbrush, a deck screw, a rubber truck strap, and some orange peels! Oh and an angle grinder to set the squish!
It was probably the rubber truck strap that made it possible................
astnmacgto
Carnac The Magnificent
Well ya! Ya gotta hold that sucker down to tha table somehows ya know (spits tobacco)It was probably the rubber truck strap that made it possible................
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Well ya! Ya gotta hold that sucker down to tha table somehows ya know (spits tobacco)
Well there ya go...............
astnmacgto
Carnac The Magnificent
In all seriousness, what are "safe numbers" as far as generic rule of thumb in degrees to keep one out of trouble
You don't necessarily build for a longer bar, you build for the activity son. What I mean is a good builder can reconize the difference in a build for a comercal tree contractor that need a specific saw to stump large trees to the duff, crossing the hardest fibers. Regardless of hardwoods or softwoods this application should be very different from the numbers that of a pro faller of the PNW. Apparently it's easier to port a saw than port suited saws? Whatever! we are all learning. If the operators aren't listening to the builders and the builders aren't listening to the operators then nobody really learns. It's much like paying for pssy and eating it through a dental dam, it's never quite right. With a non Rev limiter coil as well a peak tune and the complaints of a savvy builder such as a guy like @mdavlee my objective has been meet. @blsnelling has shown GREAT demonstrations of many extremely nice products in the "loggers build" (fallers) but he had a flood at the time I was in the market and he "took a month off".
Brian? Although we live in different countries you may be the closest living AS member to me at times and that includes many that live on Vancouver Island.
You can send me saws and I'll let you know what I think. I'll give you a chance kid...lol
Happy Holidays man
If you want to be good on all levels then remember; "form ALWAYS follows function. And for the ones buying a saw and know what they want then it's "Principals ALWAYS over personalitys"
One of the bigger problems for the first time around porters is just how far to go and staying inside those parameters, real easy to go too far too quick and ruin a cylinder. Its common for those that port and experiment a lot to go overboard if they are pushing the limits/experimenting on a certain saw model trying to get the most out of them. Small steps at a time and a good understanding of what each step will affect is needed to get good gains, its like dialing in an engine, getting more fuel mix in and getting the exhaust out nets bigger gains. Easier said than done as there is a dance going on inside the cylinder being affected by many small factors from filling the cylinder, keeping the biggest amount of fuel air mix in there, compression ratio, ignition timing, flame propagation, port timing and then getting the exhaust gases out are the main considerations but not all of them by no means.
Just giving out numbers will not guarantee the same results from one person porting to another, just not going to happen but in general some numbers are known to produce at least some gains but its the extensive knowledge a porter gains through experimentation that nets the better results. Many non porters but those wishing to start porting want instant results and ask for numbers from those that have been at this game for some time and there have been times when the experienced porters would share their findings but each and every time this has been tried a big fight will eventually break out as it becomes a contentious issue, what numbers work best for which situation, a few degrees more or less on each of the most important steps/ports does make a difference, change one and it will affect another. The more extensive the porting becomes the more sensitive the tuning becomes, affected by everything from ,air temperature, high or low atmospheric pressures, humidity and altitude as some of the things that affect tune then there is mix ratios and that can be a thread all in its self. Porting for torque, porting for speed and in between is all accomplished by manipulating the port sizes, timing and compression so one needs to know what uses the intended porting job is aimed toward.
Brian has asked for numbers that would help pull chain around a longer bar but has not stated whether its going to be a felling saw or a stumping saw and at what altitudes the saw will be used mostly. For a torquey saw his easiest gains are open the muffler and gain some compression by base gasket delete or bring the squish down to an acceptable limit, around .019 plus or minus a couple degrees will be a good starting point. Each step has to be checked by the builder/porter as not all saws of the same model or production runs are exactly the same, many manufacturers make P&c sets for the same model saws and there are differences between them so the squish on one saw of a said model can have a wide difference and port sizes, shapes and timing numbers vary as well. No one shoe fits all sizes in this game.
Just giving out numbers will not guarantee the same results from one person porting to another, just not going to happen but in general some numbers are known to produce at least some gains but its the extensive knowledge a porter gains through experimentation that nets the better results. Many non porters but those wishing to start porting want instant results and ask for numbers from those that have been at this game for some time and there have been times when the experienced porters would share their findings but each and every time this has been tried a big fight will eventually break out as it becomes a contentious issue, what numbers work best for which situation, a few degrees more or less on each of the most important steps/ports does make a difference, change one and it will affect another. The more extensive the porting becomes the more sensitive the tuning becomes, affected by everything from ,air temperature, high or low atmospheric pressures, humidity and altitude as some of the things that affect tune then there is mix ratios and that can be a thread all in its self. Porting for torque, porting for speed and in between is all accomplished by manipulating the port sizes, timing and compression so one needs to know what uses the intended porting job is aimed toward.
Brian has asked for numbers that would help pull chain around a longer bar but has not stated whether its going to be a felling saw or a stumping saw and at what altitudes the saw will be used mostly. For a torquey saw his easiest gains are open the muffler and gain some compression by base gasket delete or bring the squish down to an acceptable limit, around .019 plus or minus a couple degrees will be a good starting point. Each step has to be checked by the builder/porter as not all saws of the same model or production runs are exactly the same, many manufacturers make P&c sets for the same model saws and there are differences between them so the squish on one saw of a said model can have a wide difference and port sizes, shapes and timing numbers vary as well. No one shoe fits all sizes in this game.
drf255
BAD CAD
Depends on the Saw of course.
100/122/75 is pretty safe for all. Maybe 124 on the transfers for a long bar.
To the OP, a lathe will be helpful as well.
Trx250r180
Saw polisher
Most of them will be logging saws felling timber,a saw that has tourque is preferred so when partway through a cut and sighting up direction of fall ,needs to be able to roll the power on easy when the chain stuck with softwood chips. 440 460 and 660 saws most likely,the guys around here like the older saws still,the 461 and 661 are starting to come around for a few guys.
If you are not cutting the base then the first thing I would do is set the squish to .020, or as close as possible as a thou or two either way will not matter really. Tighter is better to a small degree. Then set up the degree wheel and check to see where the existing ports are at, some cylinders have exhaust port roof`s too high to make it to 100 by just deleting the base gasket or dropping the cylinder down to around .020 squish but if it does then you are good and grinding the rest is made easier. To get more than 100 degrees then the base may have to be shaved off to lower the exhaust roof even more, this creates more compression which should make more torque and torque is where most long bar saws want to be..
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Buy a junk saw and go at it. No matter what a learning curve is involved.
Stihl working hard
Is it Friday yet
You should be able to look all of this up on this site but here is a list of what I do. I have came a long way since porting my first 660 (the port job looked like hell but ran great).
1. Check your squish and determine if you can or want to run without a base gasket.
2. Using graph paper, map your entire port diagram. Note where your dowels are that locate your rings on the piston
3. Using the "two stroke tuners handbook" by gordon jennings that you have read front to back twice, collect all the information you need ( You will need to know how to do some algebra, easy algebra) You will need a caliper. You will be converting distances from TDC or BDC to degrees.
4. Your formulas will give you cross sectional port area and degrees for open and close. Your squares on your graph paper are 1/4 inch by 1/4 inch. Start developing your new port map on your old port map. There will be alot of math. ALOT.
5. Line your cylinder with masking tape and start tracing your new port map plan that you made on the graph paper to the masking tape on the cylinder walls.
6. Port your cylinder.
7. Chamfer the ports, polish the exhaust, knife the transfers, mod the muffler, tune the saw.
Edit: I forgot to add, match the muffler gasket, muffler opening and exhaust outlet.
1. Check your squish and determine if you can or want to run without a base gasket.
2. Using graph paper, map your entire port diagram. Note where your dowels are that locate your rings on the piston
3. Using the "two stroke tuners handbook" by gordon jennings that you have read front to back twice, collect all the information you need ( You will need to know how to do some algebra, easy algebra) You will need a caliper. You will be converting distances from TDC or BDC to degrees.
4. Your formulas will give you cross sectional port area and degrees for open and close. Your squares on your graph paper are 1/4 inch by 1/4 inch. Start developing your new port map on your old port map. There will be alot of math. ALOT.
5. Line your cylinder with masking tape and start tracing your new port map plan that you made on the graph paper to the masking tape on the cylinder walls.
6. Port your cylinder.
7. Chamfer the ports, polish the exhaust, knife the transfers, mod the muffler, tune the saw.
Edit: I forgot to add, match the muffler gasket, muffler opening and exhaust outlet.
jmssaws
Addicted to ArboristSite
Most any saw will run ok at 100 120 78-80
Quads use a little more bd
Numbers are just numbers and a very small part of it.
Most any sensibly ported saw can be a long or short bar saw,should run either
Most of that is tune
Quads use a little more bd
Numbers are just numbers and a very small part of it.
Most any sensibly ported saw can be a long or short bar saw,should run either
Most of that is tune
