squish bands

[bwalker]

I see quit a few guys cut the squish to raise compression. The squish angle always appears to be flat.
Why not angle it properly to squeeze mixture toward the center of the chamber as motorcycles or sleds do?

 

[tlandrum]

I have all my hand cutters set at a couple of degree angle but when I cut on the lathe most times its flat

 

[Deets066]

Wider, flat, tight squish band supposedly reduces the chance of detonation. A nice bevel on the edge of squish headed to the combustion chamber is customary. Air and fuel mix pushed against the squish and upper cylinder wall only has one way to go.

That being said, my 066 has a narrower squish with an 0.030 taper towards the combustion chamber and runs very well. Couldn't tell ya which was is better, I doubt you would notice the difference between the two

 

[sunfish]

There is just no real good reason to angle the squish band on a chain saw...

 

[mdavlee]

The 562 I just cut was .002" different from wall to center where it quit mashing the solder and plastigauge.

 

[bwalker]

There is just no real good reason to angle the squish band on a chain saw...

Why do you say that?

 

[tree monkey]

it's to narrow to make any difference

 

[tickbitintn]

some one on a different site may argue with that and provide "proof" with links and stuffs...... (hint, hint)

 

[tree monkey]

the new ms 661 is flat stock

 

[tickbitintn]

Depending on the method you use to cut them they will usually end up with at least a very slight taper.
Lathe would (or should) be flat. Depending on the dowel or fixture set up a slight taper would be fairly easy to accomplish.
Especially if you use emery or sandpaper on a dowel for finish sanding and blending.
I doubt there would be a noticeable or measurable difference between dead flat and a slight taper.

 

[Mastermind]

I cut em flat because it's a pain in the ass to add a 2° taper for zero gain.

 

[cgraham1]

I cut em flat because it's a pain in the ass to add a 2° taper for zero gain.

What do you do to saws with domed pistons?

 

[tree monkey]

cut the dome off

 

[drf256]

There's only one way for the charge to flow, and the piston is squeezing it at 200+ times a second.

 

[CR888]

An Indian feller named Somender Sing is doing some interesting things with squish bands, putting cuts and passages to direct charge. I have wanted to mod and test some of Sings ideas in a saw. While lots of old, older and ancient squish designs are currently used in 2T, since a german came up with an idea 80odd year ago not much has really improved or changed. It seems high out put 2t are going with flat piston with transfers angled to shoot straight across the piston but their are many variations depending on engine application number of ports etc. Angling transfers upward may be a good milling mod but due to the symetry required you would want a few hundred hours using a foredom under ya belt to get accurate good results.

 

[Miller Mod Saws]

What do you do to saws with domed pistons?

You can cut them at an angle. The 500p I just did I put it on a 3 degree angle as thats what seemed to match the piston the best. These pistion are to thin to cut flat. But say an 026 stihl. Tree monkey it!

 

[srcarr52]

What do you do to saws with domed pistons?

Match the dome angle on the outer edge of the piston. I add 2deg more than that.

 

[Hedgerow]

There is just no real good reason to angle the squish band on a chain saw...

No need to cut a squish band on an 028 super at all..
It's domed already.

 

[Hedgerow]

You can cut them at an angle. The 500p I just did I put it on a 3 degree angle as thats what seemed to match the piston the best. These pistion are to thin to cut flat. But say an 026 stihl. Tree monkey it!

Or.. Back over it with a truck...

 

[jmssaws]

What little I've messed with tapering a squish band showed no gain,it changed nothing.