Realistic performance gains with porting a saw?

[Andrew Wellman]

I have been reading up on two stroke performance tuning and have some grasp of the cause and effect of changing ports. I am going to dig into a chinese 372 cylinder for my first attempt. I have read that a 2mm drop in intake port or 2mm trim in piston is a safe standard to start from? Do you you raise the exhaust the same to balance the motor? What I understand is that this increases the peak hp rpm, thus faster chain speed, thus more work being done? The other beginners school of thought is to just widen the ports keeping them elliptical/beveled, were this keeps the timing the same, but increases the volume of mixture thus increasing the hp at stock max hp, rpm. I made a degree wheel and will be learning to use it but are there some rough guidelines for porting a work saw. Finally, what is a reasonable expectation for performance gains, 5% gain in hp or 20% gain in hp. Is this more work than its worth, and just a geeks hobby

any one?

 

[woodyman]

I have been reading up on two stroke performance tuning and have some grasp of the cause and effect of changing ports. I am going to dig into a chinese 372 cylinder for my first attempt. I have read that a 2mm drop in intake port or 2mm trim in piston is a safe standard to start from? Do you you raise the exhaust the same to balance the motor? What I understand is that this increases the peak hp rpm, thus faster chain speed, thus more work being done? The other beginners school of thought is to just widen the ports keeping them elliptical/beveled, were this keeps the timing the same, but increases the volume of mixture thus increasing the hp at stock max hp, rpm. I made a degree wheel and will be learning to use it but are there some rough guidelines for porting a work saw. Finally, what is a reasonable expectation for performance gains, 5% gain in hp or 20% gain in hp. Is this more work than its worth, and just a geeks hobby

any one?

Ain't going to get alot of answers talking like that.

 

[garyischofield]

search

Type in the "search box"any of the reputable builders on this site.Brad Snelling,(bisnelling),Randy Evans,(Mastermind),Stumpy,Terry Landrum(Tlandrum)et al.These people have posted an enormous amount of useful information about chainsaw performance improvements.Some post video's showing "before"and "after" cuts in the same log showing quantitative performance gains.Personally,I use only ported saws.The bottom line thinking is, more work /less time.I think reasonable gains are in the 25-40% range.

 

[thomas1]

Type in the "search box"any of the reputable builders on this site.Brad Snelling,(bisnelling),Randy Evans,(Mastermind),Stumpy,Terry Landrum(Tlandrum)et al.These people have posted an enormous amount of useful information about chainsaw performance improvements.Some post video's showing "before"and "after" cuts in the same log showing quantitative performance gains.Personally,I use only ported saws.The bottom line thinking is, more work /less time.I think reasonable gains are in the 25-40% range.

I like that everybody has a screen name and a real name except stumpy. He's like Cher or Madonna I guess.

 

[Andrew Wellman]

Never mean any disrespect

I never meant to disrespect anyones hard earned skill set or expertise. I have learned a great deal since that post, and still have a great deal more to learn. In my first attempt at porting, I used a scored echo 4600 (split case) saw to practice porting on. I read the two stroke tuners hand book over, and over and over again. I made some safe and modest changes to width, shape and height/depth and was blown away by the gains. It was more than I expected.:hmm3grin2orange: My own personal stock saw references were my 242xp and Dolmar 5105 and I would say that my experimental ported saw out cut the 242xp and was a match to the new 5105. And yes you are correct with your statement.

Ain't going to get alot of answers talking like that.

 

[Dennis Cahoon]

Ahahahahahaha!......Try ole GypoLogger's plan......raise the exhaust 1mm, lower the intake 1mm, widen both intake & exhaust as much as you can without creating a free port, set your squish at 0.20 then do a muffler mod, and you'll have a good worksaw.

 

[ozflea]

Ahahahahahaha!......Try ole GypoLogger's plan......raise the exhaust 1mm, lower the intake 1mm, widen both intake & exhaust as much as you can without creating a free port, set your squish at 0.20 then do a muffler mod, and you'll have a good worksaw.

Damm Damm there you go again giving out all that secret info already and you hardly know the fella

 

[Andrew Wellman]

And now to rule the world

Damm Damm there you go again giving out all that secret info already and you hardly know the fella

First it is the mighty, soul shattering, echo 4600 port job and next I will rule the world!!!!:cool2:

 

[Andrew Wellman]

Thanks

Thanks for the help. Do you live in Chico? I went to grad school in Davis and raced for the Cal Aggies mountain bike team, my favorite race was up in Chico. We were the nerds and Chico was the party school. I am going to port map my next saw to wee what I have regarding degrees/duration. How would I know if a stock saw has room for improvement or is designed almost to the max and needs very little. What are the degree ranges of intake and exhaust? Sorry I know thi may no be the correct questions to ask.

Ahahahahahaha!......Try ole GypoLogger's plan......raise the exhaust 1mm, lower the intake 1mm, widen both intake & exhaust as much as you can without creating a free port, set your squish at 0.20 then do a muffler mod, and you'll have a good worksaw.

 

[Andrew Wellman]

Ahh, I see

gyp·po   [jip-oh] Show IPA
noun, plural gyp·pos. Slang .
a logger who operates on a small budget and typically gleans the timberlands already cut by larger companies.

Then I am a "micro gyppologger" Actually logger is an overstatement. I cut 10 cord a year and have 9 acres, but I do some arborist work on the side for beer money.