When 2 Strokes 4 Stroke

[Crofter]

Macman I guess you are right . Heat and load go together. It is maddening though to get your mind around not using enough fuel for the load (lean mixture) you burn your saw up.
It is not surprising peope can get in trouble with 2 strokes!

 

[usmc50bmgsniper]

I Agree With Crofter, And That Is Why People Get Into Trouble With 2 Strokes, I Have Been Working And Racing 2 Stroke Motorcycle Engines For Years And It Is The Same As A Chainsaw, A 2 Stroke Is A 2 Stroke No Matter What It Is In, I Adust The My Carbs So That It Burns A Golden Brown And If The Plug Is White Then Your In Trouble And Beeter Richen It Up Before You Fry The Engine, Alot Also Is The Temp And Elevation Of Where You Are At, A 2 Stroke Runs Richer In The Cold Winter Weather And Elevation Will Effect It. As For The Term 4 Stroken I Always That It Meant The Cycles Of A 4 Cycle Engine Which Is The Intake,compression,power And Exhaust Stroke But I Could Be Wrong

 

[Mange]

The two stroke engine theory was not meant to be high tech. The Principals are good and the engin is sheep to pruduce, The intake fuel/air mix and exousts go in and out a little as it please. I do not mean this to be bad, simply stating the fact that there is more effective systems, just heavyer and more expensive.

 

[sedanman]

Get your heads around this.........................In a conventional 2 stroke piston ported engine 25% of the fuel/air/oil charge delivered to the combustion chamber excapes un-burned out of the exhaust. Strato-charge engines like the newer Huskies prevent this by using a dose of pure air to purge the combustion chamber. An expansion pipe could actually be used to lower emissions.

 

[Gypo Logger]

Hello Frank, what happens is that during incomplete combustion, the finger ports scavenge atomized fuel from the crankcase and transfers it to the transfer ports after it has become heated in the quad loops causing a preignition condition thereby giving a somewhat audible "pinging", sound that sounds much like the four stroking you described.
This mechanical phenomonon can be remedied by simply turning in the H to seated then back it out 1/4 turn approx.
Hope this helps Bud,
John

 

[Fish]

"Pinging?"

You might have to elaborate on this technical term, many here have not
been schooled on the pinging anomoly, and the theory behind it.

 

[WRW]

"Pinging?"

You might have to elaborate on this technical term, many here have not
been schooled on the pinging anomoly, and the theory behind it.

Otto could set us straight on that.

 

[Crofter]

John, that sounds like fair exchange for my "fatherly" advice!

QUID PRO QUO

 

[Crofter]

When a modified saw is tuned up to a higher rpm and expecially when it has a tuned pipe, it seems a little harder to know by sound what seems quite easy on a stock muffler saw. I remember some discussion a while ago about plug colours and the relation to mixture. I think some in 3 cut competitions run the saw a bit lean for that 4 or five second spurt. I have a hard time bringing myself to that. Will have to go look up that post on throttle chops. Sedanman, I believe you were in on that; do you know what it was posted under?

 

[Lawn Masters]

A 2 Stroke Runs Richer In The Cold Winter Weather And Elevation Will Effect It.

I think you've made a slight mistake here, in cold weather air is more dense, so it runs leaner, not richer. cold air has more molecules compacted together, while the molecules of oxygen in hot air are more or less scattered around.

 

[sedanman]

Frank, I remember the throttle chop spark plug controversey. Here's the thread.
http://arborist.lawnsite.com/showthread.php?t=14469&highlight=throttle+chop

 

[Mange]

Frank, I remember the throttle chop spark plug controversey. Here's the thread.
http://arborist.lawnsite.com/showthread.php?t=14469&highlight=throttle+chop

The plug in this thread has been run too hot, the yellow/brown is from the piston, the black is when all the things that stick to the walls in the crankcase etc comes of and gets ignited along with fuel/air mix.
He has no doubt gone along side a harvester just falling, then the saw gets hot fast and stay hot.
Something to try is rich the fuel just a little, keep it really clean around cylinder for better cooling, some muffler mod, but just one or two small holes.
The thing I did was drill two 5,5mm holes in the muffler and reset the carb, so it got more fuel, 200rpms lower than it was before.

Seen this a few times, all of them were going along side a harvester.

Here is another link that talks about aspen
Chainsaw Collectors Forum