working on other builders saws

[rocketnorton]

A true .012-014" will run fine. I don't like to run them that tight but after using plastigauge I had a few.

044 @ .011 here. sfsg. maybe 3 tanks in.

 

[XP_Slinger]

This is the first I've heard that squaring an intake beyond carb bore diameter is a bad thing...very interesting with sound theory. The way my brain is thinking on it, I see a squared intake acting as a plenum in that it somewhat stores some air fuel mix at the piston for the initial gulp upon port opening which "should "increase the volume of the intake charge with slightly lower velocity giving the saw greater power at higher RPM. That whole Velocity vs Volume dance is a delicate balance and as far as I understand it when you gain in one, you lose in the other to a degree.

I would imagine a saw with a narrow, high velocity intake tract would have a much broader power band at lower rpm.

Thinking out loud here guys

 

[T.Roller]

This is the first I've heard that squaring an intake beyond carb bore diameter is a bad thing...very interesting with sound theory. The way my brain is thinking on it, I see a squared intake acting as a plenum in that it somewhat stores some air fuel mix at the piston for the initial gulp upon port opening which "should "increase the volume of the intake charge with slightly lower velocity giving the saw greater power at higher RPM. That whole Velocity vs Volume dance is a delicate balance and as far as I understand it when you gain in one, you lose in the other to a degree.

I would imagine a saw with a narrow, high velocity intake tract would have a much broader power band at lower rpm.

Thinking out loud here guys

I don't have near enough experience to agree or disagree. It sounds good tho

 

[Keith Gandy]

This is the first I've heard that squaring an intake beyond carb bore diameter is a bad thing...very interesting with sound theory. The way my brain is thinking on it, I see a squared intake acting as a plenum in that it somewhat stores some air fuel mix at the piston for the initial gulp upon port opening which "should "increase the volume of the intake charge with slightly lower velocity giving the saw greater power at higher RPM. That whole Velocity vs Volume dance is a delicate balance and as far as I understand it when you gain in one, you lose in the other to a degree.

I would imagine a saw with a narrow, high velocity intake tract would have a much broader power band at lower rpm.

Thinking out loud here guys

Seems if u went too large and stored the fuel as u r saying is where the pooling would happen resulting in poor idle and acceleration?

 

[XP_Slinger]

I don't have near enough experience to agree or disagree. It sounds good tho

I'm not sure if I understand it either, I blacked out for a minute: what happened? LOL

Part of my thought process is based what I know about building SBCs. Not a chainsaw, but still an engine so some things cross over.

 

[Keith Gandy]

I'm not sure if I understand it either, I blacked out for a minute: what happened? LOL

Part of my thought process is based what I know about building SBCs. Not a chainsaw, but still an engine so some things cross over.

Im in the boat with u!! Lol!

 

[XP_Slinger]

Seems if u went too large and stored the fuel as u r saying is where the pooling would happen resulting in poor idle and acceleration?

I think so Keith...One can definitely go too big with squaring. What is too big? This guy don't know, that's where years of experimenting come into play as we know. I'm sure we all have run strong saws with squared intakes that idle just fine. Balance balance balance

 

[Keith Gandy]

Someone help me here. If u notch the butterfly for more airflow this pulls more fuel in over the venturi?

 

[afleetcommand]

This is the first I've heard that squaring an intake beyond carb bore diameter is a bad thing...very interesting with sound theory. The way my brain is thinking on it, I see a squared intake acting as a plenum in that it somewhat stores some air fuel mix at the piston for the initial gulp upon port opening which "should "increase the volume of the intake charge with slightly lower velocity giving the saw greater power at higher RPM. That whole Velocity vs Volume dance is a delicate balance and as far as I understand it when you gain in one, you lose in the other to a degree.

I would imagine a saw with a narrow, high velocity intake tract would have a much broader power band at lower rpm.

Thinking out loud here guys

And your a Honda guy...remember what the "rap" against Honda's 125's from the early 2000's was?

 

[blsnelling]

I'm sure his race saws are in the hunt for the win. I'd like to see him do an alky or funny fuel build on here. seems best suited to his style of port work.

Do I know you by another name?

My piped 390XP is the only saw I've ever really attempted to take past a work saw build, and it's very much still a work in progress. I'm toying around with a 346 right now, but it's just a work saw with a bigger carb.

I'm too chicken to put alky in my saws, lol.

I too am trying to figure out whose saw this is, only out of curiosity. They do clean work, but looks like they went a wee bit too far in a couple different areas. A little too far can make a big difference in one of these!

 

[czar800]

I'd love to wash dirty saws and sweep chips off the floor in a few of you guys shops.

 

[T.Roller]

I'd love to wash dirty saws and sweep chips off the floor in a few of you guys shops.

Troof

 

[blsnelling]

A couple questions come to mind.

Have you checked the squish? Any chance there could be a bottom end bearing issue at play here, allowing the piston to over-travel?

Was this cylinder new to this saw? How would the plating get worn through in such quick order?

 

[XP_Slinger]

And your a Honda guy...remember what the "rap" against Honda's 125's from the early 2000's was?

Honda trikes...LOL. Fill us in Walt; what was the "rap"?

 

[Hedgerow]

I'd love to wash dirty saws and sweep chips off the floor in a few of you guys shops.

Not me..

These guys are messy.

They need to clean up after themselves..

 

[Deets066]

A couple questions come to mind.

Have you checked the squish? Any chance there could be a bottom end bearing issue at play here, allowing the piston to over-travel?

Was this cylinder new to this saw? How would the plating get worn through in such quick order?

Could have been a used saw that was ported. May have a lot more time on it

 

[paragonbuilder]

Someone help me here. If u notch the butterfly for more airflow this pulls more fuel in over the venturi?

I believe that would only be for idle, Keith, and would depend where you notch it. At WOT the notch would be irrelevant.


Sent from my iPhone using Tapatalk

 

[afleetcommand]

Honda trikes...LOL. Fill us in Walt; what was the "rap"?

Too much volume in the intake tract..peaky...no torque. The short answer..

 

[XP_Slinger]

Too much volume in the intake tract..peaky...no torque. The short answer..

Thanks Walt...Kinda aligns with what I was thinking. Too much volume not enough velocity and the power band is narrow at a higher rpm (all or nothing kind of power). Lower volume with higher velocity creates broader/torqyerererer power over a wide (but usually lower) rpm range.

 

[wcorey]

Someone help me here. If u notch the butterfly for more airflow this pulls more fuel in over the venturi?

Assuming the notch in question is over the idle jet, the notch is the venturi, at least until the throttle plate is opened enough so the main venturi has enough flow to start functioning.