Thread: what is cylinder porting?

I wand some of those porting and moding.
I`ll ask in the chainsaw forum

Originally Posted by The Count

I wand some of those porting and moding.
I`ll ask in the chainsaw forum

Not sure what you are asking. Are you looking for someone to port your cylinder head, or for advice on how to do it yourself?

Originally Posted by Haywire Haywood

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

I am planning to do some porting on my saw for woods use, which would I port just intake exhaust? Or more, I have been reading porting 101 also. Thanks

Originally Posted by edisto

Not sure what you are asking. Are you looking for someone to port your cylinder head, or for advice on how to do it yourself?

considering that most of you guys are Made in USA and I am Europe,
I`ll have to do that myself. (if ever)

is there a video from A to Z of MM & Porting ?

Originally Posted by The Count

is there a video from A to Z of MM & Porting ?

Not that I know of, but there is an excellent reference available free online as a pdf here. It was written for motorcycle engines, so there are things that are not directly applicable, but it is an excellent overview of the considerations.

As far ar port work, I've done plenty. But only a tid bit on 2 cycles.
The moving of ports up or down should change the power curve up or down in respect to rpm. Which I don't know why any one would change.
The simple freeing up of flow restrictions should make it easier for the motor to run. If the motor has a hard time pumping air that costs power. And if the motor has a hard time it runs hotter.
I have an alaska mill 36 inch. powered by an older "ported"(not by me) 2101 xp. It mills fine, slow but you can't really stall the saw, even with great effort. So I know a little bit.
But in larger milling you need more torque. And don't need to care about wierd size or shape. Modification should be made in my opinion to the intake tract length for more ram air affect. Simply cramming more air into the sump, and better cylinder clearing. The exhaust as well. I hate to say but its probably about a foot, a cut aluminum base ball bat probably has about the proper included intake angle and length.
I have to caution that the dynamic compression ratio will change dramaticly, and could for all I know cause problems not relaited to over heating. Like the saw breaking in half or tearing the cylinder bolts from the case.
Look to a 125 cc bike, they have room for the package and the lengths are conciderable for the intake and exhaust. And the power of the motor is much more.
I guess in summation saws are made for simple cutting of wood not milling.
Buy a super 90 stihl.
spell checker won't work

Hi there new here, i am looking to find out were i can get a 390xp saw worked over for the woods my 395xp just geting to heavy for my back i have herd that a good porting can make a big change.

Originally Posted by Logman1974

Hi there new here, i am looking to find out were i can get a 390xp saw worked over for the woods my 395xp just geting to heavy for my back i have herd that a good porting can make a big change.

I can do that for you. You may want to take a road trip some day and run a few of my saws. I am about 3 1/2 hours away from you, just east of Lewistown.

Later
Dan