Poulan 4000 Stock Numbers

[Thesandman]

First time I've ever done this so if not right don't be surprised. I've got ex open@98.5atc for163* dur. not much power stroke. Trans @124.5 for 111* and int@65btc for 130, blow down 26*. Looking over other saw numbers either I did it wrong or these are moderate numbers except ex opens a lot sooner than modern saws. If these numbers are correct, what would you suggest? Thanks.

 

[David Young]

Compression and bump the intake to 74

 

[Thesandman]

Thanks David; I wish there was a way to open int earlier and close it earlier. Don't think there is a lot available looking at cylinder. Ex is already maxed for size at muff flange. Intake track is long with a 45* bend at cylinder.

 

[David Young]

Lower the intake floor 1.5-2 mm. Make sure you have a nice chamfer on the port when you are done.

 

[Thesandman]

Couple of things I've learned. #1. I'm done with piss reving my saws. I don't care what that number is and it makes me cringe every time. Speed in cut is what I'm interested in. #2. Looking at cylinder I find myself reluctant to mod ports(scared even). They appear to match and everything seems good. I was hoping for simple fixes of mfg,s flaws but see none. Trans are open and easy to get to. The intake has a divider in middle of port that I'm not sure of its purpose. Rings don't go down that far. Base gasket is .010 so a delete won't show much. Squish is .050 but band in cylinder is very wide creating a cave type hole around spark plug. Piston and cylinder look good with light coat of black on both domes and ex port. No heat indications anywhere. I'm thinking I could file the cyl base down .025 and stay with gkt. Thoughts?

 

[Stump Shot]

Couple of things I've learned. #1. I'm done with piss reving my saws. I don't care what that number is and it makes me cringe every time. Speed in cut is what I'm interested in. #2. Looking at cylinder I find myself reluctant to mod ports(scared even). They appear to match and everything seems good. I was hoping for simple fixes of mfg,s flaws but see none. Trans are open and easy to get to. The intake has a divider in middle of port that I'm not sure of its purpose. Rings don't go down that far. Base gasket is .010 so a delete won't show much. Squish is .050 but band in cylinder is very wide creating a cave type hole around spark plug. Piston and cylinder look good with light coat of black on both domes and ex port. No heat indications anywhere. I'm thinking I could file the cyl base down .025 and stay with gkt. Thoughts?

You're thinking in the right direction. There isn't much of a squish band on these if I recall correctly, but dropping it down will definitely put the numbers in a better place.

 

[Thesandman]

If I want to move ex from 98 to say 102 on a 34.5mm stroke how much do I need to cut off base? I know I'll have to cut squish band also.

 

[Stump Shot]

If I want to move ex from 98 to say 102 on a 34.5mm stroke how much do I need to cut off base? I know I'll have to cut squish band also.

Find the feeler gauge thickness that moves the degree wheel one degree, then do the math from there.

 

[huskihl]

If I want to move ex from 98 to say 102 on a 34.5mm stroke how much do I need to cut off base? I know I'll have to cut squish band also.

You’d have to lower the cylinder down about .050”

 

[Thesandman]

Thanks SS; appreciate it. Hey Kevin, thank you. I'm finding out these 2 strokes are very complex for being so simple.

 

[Thesandman]

Ok I have #2

First time I've ever done this so if not right don't be surprised. I've got ex open@98.5atc for163* dur. not much power stroke. Trans @124.5 for 111* and int@65btc for 130, blow down 26*. Looking over other saw numbers either I did it wrong or these are moderate numbers except ex opens a lot sooner than modern saws. If these numbers are correct, what would you suggest? Thanks.

Opened #2 and numbers are close to original.#1 98.5ex, 124.5trans, 65int. #2 is 99ex, 124trans and 64int.

 

[Thesandman]

Ok I have #2

Opened #2 and numbers are close to original.#1 98.5ex, 124.5trans, 65int. #2 is 99ex, 124trans and 64int.

I cut .040 off cylinder base and traded a .010bg for a 020. Squish is 20 and new numbers are 100ex, 127 trans and 67 int. I think I will go back to .010bg and cut squish ten. Shoot for 102ex, 124trans and 70int(maybe bg delete). Have to see how it runs