Chainsaw Porting Theory

[Deets066]

Id probably say lost velocity and very quick to progress backwacks instead of gaining. Ive been thinking lately on 25% of the transfer on the intake side adjusted to desired port # and leave the other close to factory?

Well the pic above with two sets of bridges and a pair of fingers is the best running saw I have, go figure huh

 

[Keith Gandy]

Well the pic above with two sets of bridges and a pair of fingers is the best running saw I have, go figure huh

Im thinking that will work with bigger cc saws but maybe not in smaller saws ?

 

[Deets066]

Im thinking that will work with bigger cc saws but maybe not in smaller saws ?

That could be...... But why?

 

[Keith Gandy]

That could be...... But why?

Not sure just a thought. Maybe more torque in a bigger saw that will help overcome opening thoso transfers up so much and losing crankcase compression/velocity?

 

[Deets066]

Not sure just a thought. Maybe more torque in a bigger saw that will help overcome opening thoso transfers up so much and losing crankcase compression/velocity?

That's very possible, I think transfer height plays s big part here too.



This jug made a turd out of my hybrid, but trans are higher than the pic above

 

[Keith Gandy]

Im thinking if u hog the transfers out too much and hog the exhaust out and too high timing on both u will make a turd. Im seeing tighter transfers will let u go alil higher on the exhaust and still retain trapped compression and more velocity with less backpressure in the exhaust area

 

[Keith Gandy]

Or vice versa. If u need more fuel increase transfer but take less in exhaust. Im seeing a proportional balance needed between the exhaust and transfer or bottom and topend

 

[Keith Gandy]

That's very possible, I think transfer height plays s big part here too.

View attachment 15067

This jug made a turd out of my hybrid, but trans are higher than the pic above

In that situation if adding thoso fingers id say u would need to do very little on the main but maybe aim the sides alil

 

[Keith Gandy]

Fingers and opening the transfers up is taking an awful lot of crankcase capacity out and imo if too much is taken out will make what I call a lazy saw. Was this what u were thinking when u added the epoxy back in to the transfers or just seeing what would happen with more or less here and there?

 

[Keith Gandy]

Just thoughts rambling around in this noggin fellers!!

 

[Deets066]

Fingers and opening the transfers up is taking an awful lot of crankcase capacity out and imo if too much is taken out will make what I call a lazy saw. Was this what u were thinking when u added the epoxy back in to the transfers or just seeing what would happen with more or less here and there?

That's exactly the way I see it Keith, this saw had a low BD, I could possibly raise the exhaust a little to gain BD which would help

 

[Keith Gandy]

That's exactly the way I see it Keith, this saw had a low BD, I could possibly raise the exhaust a little to gain BD which would help

It always makes me alil nervous goin up on the exhaust. Man there is a quick tipping point that will screw the balance of torque and rpm up very fast. Thats what im thinking when I port for long or short bar and the transfers the same

 

[Keith Gandy]

Ive noticed lately Randy likes alil more intake duration on thoso hybrids Deets. I think about 81 on the intake floor? Im at 102/118/78 on mine and didnt hog anything or add fingers or bridges and im pretty happy with it

 

[jmssaws]

I was trying new stuff,going to see how short of blow down i could run and I found it so mission accomplished.

 

[Keith Gandy]

I was trying new stuff,going to see how short of blow down i could run and I found it so mission accomplished.

I figured u was dyin everything red!!lol!!

 

[merc_man]

View attachment 15066

They just look cool

Thats a good pic. I see better now.

 

[Keith Gandy]

I was trying new stuff,going to see how short of blow down i could run and I found it so mission accomplished.

Let us in on it and why!! Me and deets been brainstormin!!! Lol! Teach me something or just confuse the hell out of me please

 

[jmssaws]

Thats a good pic. I see better now.

I like to take blurry and fuzzy pics, kind of like I'm taking pics of Bigfoot.

 

[jmssaws]

Let us in on it and why!! Me and deets been brainstormin!!! Lol! Teach me something or just confuse the hell out of me please

13 degrees of blow down won't work,16 will though.

I guess it just plain and simple needs more time. No fancy answer because I really don't know.

 

[Keith Gandy]

13 degrees of blow down won't work,16 will though.

I guess it just plain and simple needs more time. No fancy answer because I really don't know.

066?