Thread: what is cylinder porting?

i am looking to buy a used 395xp that has been ported. what does this mean? how is a cylinder ported? can any saw be ported? how much power does this add? does a ported saw wear out faster than unported? also, are dual ported mufflers worth the effort? thanks! -nick

If it's ported the right way it will have more power, run stronger and cooler, ask the seller who ported the saw !!

In general terms, there is a "race port" and a "work" or "woods port". A good work port ads 25-40% to the cut speed without sacrificing engine life. The saw actually runs cooler because of the increased fuel/oil mixture going thru the engine and the exhaust being opened up. A race port adds much more than that but at a substantial cost in engine life.

See if you can find out who did the porting. If it's a familiar name to someone here you'll probably be ok, but if any ol hack took a grinder to it they might just as easily have trashed the top end.

Do a search for "muffler mod" down in the chainsaw forum and you'll find a large amount of reading. A muffler mod is just adding an extra outlet to the exhaust and then retuning the carb. That alone will give you a 10-20% bump as the manufacturers have them choked off pretty good to meet EPA requirements.

good luck,
Ian

thanks for the info, that is helpful. i have asked the seller, but he doesn't want to offer much info and has sent back grunt-like responses to my questions. here's another question...will any small engine repair guy know how to port a chainsaw right? or is it a fine art that needs tons of experience. can anyone refer me to a good saw mechanic in virginia around blacksburg, or near princeton, WV. thanks!

Originally Posted by vamtjewboy

thanks for the info, that is helpful. i have asked the seller, but he doesn't want to offer much info and has sent back grunt-like responses to my questions. here's another question...will any small engine repair guy know how to port a chainsaw right? or is it a fine art that needs tons of experience. can anyone refer me to a good saw mechanic in virginia around blacksburg, or near princeton, WV. thanks!

If he's not forthcoming with specifics, I'd not touch it with a ten foot pole UNLESS it's real cheap....cheap enough that you can drop $250 in it and still come out on top, and if it's that cheap, I'd be scared of it just for that reason.

I'd guess that most average small engine guys would give you the "deer in the headlights" look if you asked them about porting a saw. If you want to get a saw ported, pick up a few names from around here. Those guys are reputable and make their living at it. They know what they are doing. The Three I am familiar with are Ed Heard (Contact is in NY but he is in Canada), Dave Neiger (MI), and Dean at washingtonprosaws.com. Dean's screen name here is "Klickitatsacket". Dave's is "Dneiger"

I was talking to a fellow down here a couple weeks ago that has been logging for 30 years and had no clue what a woods port or a muffler mod was. He said they had a faller that would lean a saw out till it screamed and would burn up in about 2 weeks of use, but he was so productive that they just kept buying him a new saw. They could have saved thousands if they had just muffler modded a saw to give it that extra oomph that the faller was looking for and told him to stay off the carb screws.

Ian

the seller of the ported 395 wrote a very descriptive message back to me. it was done by a professional shop that also does racing saws. he has only used it for big trees occassionally and always used ams oil two cycle in it. i think i am going to post a question about that...if people think it's worth the money. what do u think? thanks again. -nick

how could i get in touch with a reputable cyliner porting shop someone who is experienced i have heard of the name dave niegel can someone point me in the right direction

Post your question over on the chainsaw board. There are several active members there.

dual port mufflers are worth it. i wasnt impressed with my 660 bone stock. it lacked alot of power. so i put one on my it and bumped the sprocket to an 8 tooth and its like night and day difference. alot of your power can be gained out of the exaust on two strokes.

Originally Posted by john1gilboa

how could i get in touch with a reputable cyliner porting shop someone who is experienced i have heard of the name dave niegel can someone point me in the right direction

If your doing a 395xp I'd talk to Treeslinger.

Originally Posted by vamtjewboy

the seller of the ported 395 wrote a very descriptive message back to me. it was done by a professional shop that also does racing saws. he has only used it for big trees occassionally and always used ams oil two cycle in it. i think i am going to post a question about that...if people think it's worth the money. what do u think? thanks again. -nick

Since you posted in the Milling forum I assume you are going to use the saw for milling. I would not use a racing ported saw for any kind of milling and I would still be careful of using a so called woods ported saw for milling as there is no clear line between the two. Milling is far harder on saws than any other kind of cutting and if the porter has tweaked the saw just that bit too far so that it could survive normal cutting, it may still not survive milling operation, and you could end up with a cooked saw. There are porting improvements that benefit milling but the porter needs to know the loads imposed by milling and where to draw the line.

Porting is really pretty simple once one understands the basics of how engines work. If you can carry on a conversation about the differences of cam durations and lift profiles, it's probably not a big deal to figure out how to port a 2-stroke.

Raising the ports is the same as going to a longer duration cam. You have the ability to change intake and exhaust separately, but both are constrained by the fact that the piston 'works' the 'valves' so it's impossible to get anything but symmetrical profiles about TDC.

The easiest port job is just to take the oval shaped exhaust port and make it more square. Don't expand anything but the corners and even then they still need to be rounded and the new port edges chamfered to match. Push the square profile all the way out to the muffler can and open up the muffler to match the port as closely as possible. Exhausts like to be semi-polished too. Easy way to get some cheap power.

IF you can't get that done without asking more questions, it's probably best not to mess with it.

Originally Posted by BobL

There are porting improvements that benefit milling but the porter needs to know the loads imposed by milling and where to draw the line.

It would be great if you could elaborate on that sometime (when you have the time)

Originally Posted by Rockfarmer

It would be great if you could elaborate on that sometime (when you have the time)

RF, Benefits from porting is a conclusion I have made from reading the forums and not from direct experience. As HH has already said, a moderate level of porting can help a saw run cooler. Providing the mechanicals can handle it on a long term basis, this clearly benefits milling. The big question is, what does "moderate" mean ie how far can we go? A moderate woods porting would appear to be a good start for a milling saw and then progressively increasing the porting and regularly milling with the saw and seeing what happens. Unfortunately this will probably cost at least a piston and it won't provide info on the longer term effects of the porting on the saw.

There are fellas in this and the CS forum that are very knowledgeable about porting. Unfortunately milling is not their main game so a "milling port" is not on their radar. For us on this forum I would be really useful to know what the porting boundaries are for heavy duty milling, and maybe lighter duty milling. The porting pros will have a good idea about this but probably rightfully treat this information as IP.

I will now take this to a new thread and start by asking some questions.

If I had a saw torn down to modify it for milling, I think I'd want to have the piston fully coated (ceramic insulation on the crown, permanent lube on the skirts). If I were to buy the coatings and coat the piston at home, I'd do the combustion chamber and exhaust port too.

http://www.techlinecoatings.com/CoatingProducts.htm