squish bands

[Redfin]

Mixture will indeed get trapped in the quiet if it's designed poorly. It's actually a pretty big spare of unburnt HC emmissions in four cycles as the mixture in that area often doesn't combust.

Other than unburnt hc, are there any other side effects to "trapped" charge?

 

[Hedgerow]

yes that was an alchohol saw I built foe les out in mo ,he went by logging 22

I haven't talked to Les in quite a while.
Hope he's doin ok..

 

[bwalker]

Other than unburnt hc, are there any other side effects to "trapped" charge?

In a two cycle it's the source/ cause of detonation. Though this isn't an issue in saws as they have fairly low compression ratios and the motors are not typically loaded very hard. Milling would be the exception.

 

[Hedgerow]

When milling, I've not noticed a harder "Load", per say, being put on the 9010 than any other application.
I do, however know the length of run at full throttle is way the hell longer than dropping trees, and no break to idle.
So I'd think heat dissipation would be the largest concern of a fellow running a chainsaw mill.
Seems more fuel mix flowing into the crank case would be even more important than a richer oil to gas ratio.

 

[junkman]

When milling, I've not noticed a harder "Load", per say, being put on the 9010 than any other application.
I do, however know the length of run at full throttle is way the hell longer than dropping trees, and no break to idle.
So I'd think heat dissipation would be the largest concern of a fellow running a chainsaw mill.
Seems more fuel mix flowing into the crank case would be even more important than a richer oil to gas ratio.

With free flowing exhaust i have milled several hours on end without overheating ,just keep the chain sharp so the powerhead is not overworked .

 

[Hedgerow]

better view of the flat squish band and torrodial chamber
View attachment 5256

Crude measuring from the screen puts the cross sectional area of this band somewhere between 60 and 70% of total area?
Don't have the actual measurements, but just a visual of proportions.

 

[bwalker]

When milling, I've not noticed a harder "Load", per say, being put on the 9010 than any other application.
I do, however know the length of run at full throttle is way the hell longer than dropping trees, and no break to idle.
So I'd think heat dissipation would be the largest concern of a fellow running a chainsaw mill.
Seems more fuel mix flowing into the crank case would be even more important than a richer oil to gas ratio.

Both are very important when milling. As you noted the time at full throttle is much longer thus the migration time is very short. In addition milling does load the motor more than bucking and that's easy to prove based on the fuel requirements.

 

[Hedgerow]

Both are very important when milling. As you noted the time at full throttle is much longer thus the migration time is very short. In addition milling does load the motor more than bucking and that's easy to prove based on the fuel requirements.

Define "load". We may have a gap in terminology. A full throttle cut dropping a saw from 14,000 rpm to 10,000 rpm whether bucking a large log, or laying on it's side milling a 20" slab would seem the same from a layman's perspective. Or does length of duration at said full throttle somehow add to "load"?

 

[Hedgerow]

Hell.. I may learn something today..

 

[Mastermind]

I learned one thing a lot of saws ago.

If I try to incorporate what works on bikes and sleds into my saw building.......I end up wasting a lot of time.

 

[mdavlee]

Depending on chain cross cutting I may see 1k more rpm than milling. I touched one up the other day and had to hold the saw back the first cut, second cut was self feeding on its own, and third was a little push halfway through. First cut was 9k rpms or so and it went up 500 by the end of each cut. I need to get a hardline tach so I can watch it easier. 6.5 minutes without letting off the trigger is a long time.

 

[Redfin]

Both are very important when milling. As you noted the time at full throttle is much longer thus the migration time is very short. In addition milling does load the motor more than bucking and that's easy to prove based on the fuel requirements.

What is migration time?

 

[tree monkey]

he's talking about residual oil in the crank case.
don't know what that has to do with squish bands

 

[Mastermind]

Am I confused?

 

[tree monkey]

yes, me too

 

[Mastermind]

I'm thinking the experience that we have seen firsthand trumps theory.

But.........I've learned a lot by staying open minded.

 

[tree monkey]

we can talk theory all day and get nowhere

 

[Hedgerow]

we can talk theory all day and get nowhere

This is true...

I'm good at getting nowhere..

 

[bwalker]

What is migration time?

The amount of time it takes oil to migrate through a motor.

 

[Hedgerow]

And sometimes I get nowhere fast..