How a two stroke works!

[Reckless]

I came across this page by accident but I thought it might be interesting to some of you. Because alot of the time 2smoker descriptions stop short of how the expansion chamber works in the proceess. This one doesn't, so I thought I'd post it for all those that might be interested in understanding their 2smokers better!

If your interested click here

Nice gif at the end someone made! Shit I even managed to attach it to the post!! LOL!!!

[merv]

I came across this page by accident but I thought it might be interesting to some of you. Because alot of the time 2smoker descriptions stop short of how the expansion chamber works in the proceess. This one doesn't, so I thought I'd post it for all those that might be interested in understanding their 2smokers better!

If your interested click here

Nice gif at the end someone made! Shit I even managed to attach it to the post!! LOL!!!

Yeah smart fellah that invented the expansion chamber and figured out how to stuff more charge into the cylinder.

Wasn't that Kaaden from East Germany and MZ and Degner defected with his secrets to Suzuki? http://en.wikipedia.org/wiki/Ernst_Degner

[YellowDog]

Did this at school in the late 1960s.

Thanks for the recap

[oldskool]

Thanks for that, the animation of the expansion chamber in action gives me a clearer understanding of why I have so much oil dripping out of my muffler.
I must go and reseat mine back into the barrel with a new gasket so it doesn't leak as it does.

[camchain]

I love these things. Haven't seen this particular ani before. I reckon it's being a bit optimistic re efficiency of expansion chamber negative pressure wave controlling how much of the fresh charge is wasted out the exhaust. Grubby ol' 2 strokes!

When I see an ani like this I always wonder if a 2t exhaust valve of some sort could work. Reed valves were certainly a big improvement on the intake side.

I have a question re 2 stroke lubrication that someone here will probably know. I read an interesting tech article a while ago which I'm sure described a pool of oil in the crank which is constantly being replaced/replenished. I've never pulled a 2t down that far so I don't know if this is true.

[Reckless]

I would guess not true it'd run like a pig if at all. There is way enough oil in the Petrol to lube the big end which is being replaced/replenished constantly anyway. Unless your running really high compression how often do you do a big end "very seldom" no need for a pool of oil in there as well I reckon.

[camchain]

I would guess not true it'd run like a pig if at all. There is way enough oil in the Petrol to lube the big end which is being replaced/replenished constantly anyway. Unless your running really high compression how often do you do a big end "very seldom" no need for a pool of oil in there as well I reckon.

Hmm Seems like you would have seen this 'pool of oil' if it was there - when disassembling an engine. I don't think I saved the article but was pretty in depth and (from memory) the author noted what he described as a 'common misconception' re 2t lubrication. i.e. he reckoned main lubrication comes from some oil remaining after combustion and this is where main lubrication comes from, not when oil is supended in charge of fresh fuel. I also think Ive heard somewhere that not everything on the Net is true though...

Just quietly - I'm still dicking around with my jetting.

[Reckless]

If the pool of oil was deep enough for the crank to be dipped in it wouldn't it be smashed about so much it'd be dragged up the ports and into the combustion chamber. I still can't see it working at all! Its not like a four stroke. I would also guess not every drop of Fuel/oil mix is shoved up the transfers ports so there is always some oil in the bottom end area at all times anyway.
s
Now I've gotta sign off and do some bloody work myself!! LOL!!!

[secondfield]

Supercharged via sonic energy huh .... quite bloody amazing really.

[IIIRII]

I always thought Bill Wisenewski invented the tuned pipe

http://www.modelaircraft.org/files/m...Wisniewski.pdf

Areomodelling guys were light years ahead of other 2 stroke people

And still are

[clmintie]

Don't know if Bill really was first, but look at the performance these guys are getting out of modern motors... Very cool, they sound amazing. I have a mate who's just s a bout to go to the world champs, his dedication and metallurgy knowledge is bordering on the insane....

Specification: F2A 15.Top 2007

* RPM 42000
* BHP 2.27
* volume 2.48 cc
* bore 15 mm
* stroke 14 mm
* piston / liner - DISPAL 226 (30%Si)

[Reckless]

F***ck me!! 42,000 revs thats huge!

[camchain]

If the pool of oil was deep enough for the crank to be dipped in it wouldn't it be smashed about so much it'd be dragged up the ports and into the combustion chamber.

Yeah reckless, as much as I quite liked the pool of oil idea, I thought the same thing as you, hard to imagine oil that deep where it didn't just get splashed outta the way.

Expansion chamber probably really only does the business at higher revs where port timing and chamber resonance hits a sweet spot - hence the term "getting on the pipe." Trials bikes don't have the big exhaust power bulge but produce plenty of low end/mid range grunt.
One of the best things about 2 strokes is that sexy expansion chamber - it's purty.

[camchain]

Crazy little engines. 42,000 revs is wicked. Would like to see the dainty wee dyno that measured the power output! Tiny carb must be a difficult thing to make and tune.

[Motu]

The expansion chamber is using the same sonic impulses as used in 4 stroke tuning - but because the 2 stroke exhaust signal is so weak,it needs to be amplified.Before the loud speaker,people amplified their voices with a megaphone....and at the other of the scale,people hard of hearing amplified sound with a hearing trumpet...the megaphone in reverse. So you have the two main components of an expansion chamber.