Raising Exhaust point of view

[NPKenny]

Often when I hear people speaking of modding a saw, they speak of widening the ports and raising the exhaust while lowering the intake. I have seen numerours posts referring to this, but have yet to come across

For reference sake to me, if I am looking at the front of a saw with the muffler removed, is raising the exhaust referring to slightly milling the top side of the exhaust port? Additionally, would lowering the intake be just the opposite.

Conceptually, this would mean the cylinder would begin to fill with fuel and air sooner on the intake side and evacuate slightly sooner on the exhaust side.

Thank you.

 

[huskydave]

yes the exhaust port is raised and the intake is sometimes modified. I will be posting some more pics on the 026 that I am working on. I am using a dremel with a stone to open the ports up. The transfer ports can also be modified to get gains. It depends on the saw and how much performance you are after as far as how much material to remove and from where that is the big question. I have decided to remove the base gasket and use permatex gasket sealer to lower the jug and increase compression and I will raise the exhaust port about . 026 thou or 1mm and that should give me the results I want. Some transfer ports require special 90 degree tools to modify it all depends on the saw in question.

 

[NPKenny]

Thanks for the verification.

I will look for the pictures of the 026. I would really like to see pictures of a person working on the transfers so that I can see the approach taken to get certain results. I know a lot of the tricks are boderline proprietory, but I just want to tinker with making the saws I am working with really work while I have them apart.

 

[heimannm]

Check your measurements

1 mm = .0394" or there abouts. 0.026" = 0.667mm

 

[huskydave]

Yes sorry I was thinking of the conversion number and not the actual conversion. 25.4 is the magic number I believe. 1mm is .040 thou rounded off

 

[heimannm]

Don't want to be picky

I get in trouble a lot for painting with a broad brush. I suppose in reality the difference between 0.026 and 0.039 is pretty small.

 

[Trigger-Time]

I get in trouble a lot for painting with a broad brush. I suppose in reality the difference between 0.026 and 0.039 is pretty small.

That depends,if you are trying to put a .039 pin in a .026 hole

Then its a bunch :hmm3grin2orange:

 

[huskydave]

Hey trigger that's right but I would rather have a tight hole than a loose one!:hmm3grin2orange: :hmm3grin2orange: :hmm3grin2orange:

 

[Trigger-Time]

Hey trigger that's right but I would rather have a tight hole than a loose one!:hmm3grin2orange: :hmm3grin2orange: :hmm3grin2orange:

EASY their........:biggrinbounce2:

 

[Tzed250]

I get in trouble a lot for painting with a broad brush. I suppose in reality the difference between 0.026 and 0.039 is pretty small.

Jiminy Christmas, i have to work inside of .003 most of the time...I would love to have .013 to play with!

 

[troutfisher]

I get in trouble a lot for painting with a broad brush. I suppose in reality the difference between 0.026 and 0.039 is pretty small.

Maybe, .026-.039 is .013", not a lot when raising a port....A lot when setting squish....A Whole Bunch when fitting a piston or bearing............Nothing when cutting a 2x4. It's all relative.

 

[Erick]

Hey trigger that's right but I would rather have a tight hole than a loose one!:hmm3grin2orange: :hmm3grin2orange: :hmm3grin2orange:

EASY their........:biggrinbounce2:

Jiminy Christmas, i have to work inside of .003 most of the time...I would love to have .013 to play with!

This thread is headded south quick.

 

[heimannm]

Big machines, tight tolerances

The company I work for makes some large flaking mills used in vegetable oil extraction. The largest rolls are 32" diameter x 84" long and essentially solid nodular or chilled cast iron. They produce flakes from end to end that should average 0.012" and cannot vary by more than 0.002-0.003". We have a device that we can mount on these machines and regrind the rolls in place, and when finished need to be true to <0.0015" variation along the length, with a slight taper or relief at the ends, say 0.002" tapering over 12" to account for the way the rolls wear unevenly in operation. If can be a real challenge getting these rolls back in order if a customer abuses the machine or ignores them for too many months. I certainly understand that 0.013" can seem like a whole lot or just a tiny little bit depending on your point of reference.

 

[NPKenny]

In the interset of porting, it does appear that the calipers will be well used as my eye does not know what .013" looks like. I am getting a feel for the range of clearances.

Good info in the midst of a derailment. This sight is well worth the free admission.

 

[Al Smith]

. I certainly understand that 0.013" can seem like a whole lot or just a tiny little bit depending on your point of reference.

What until you have to work in microns.That's like the fuzz on a gnats behind.