What is the Mechanical Difference between a 2 stroke and a 4 stroke? Why can you get so much more power out of a 2 stroke with smaller displacement?

Also why must you mix oil with the gas for the 2 strokes? I'm gonna guess, but I'm probably wrong. Is it because a two stroke runs higher compression and you need the oil to raise the flash point and prevent detonation?

Sorry for the ?'s

 

The main difference is that 4 strokes have valves like your car. The air/fuel mixture is pulled in,burnt,and exhausted in four strokes of the piston. 2 strokes pull the mixture, burn it, and exhaust it on 2 strokes. 2 strokes don't have valves but something called reeds with acts like a vavle for the air.( I think) The oil is to lubricate the piston and sleeve so the motor doesn't just burn up and seize the piston against the cyclinder wall, although sometimes it does happen. This is just from the little bit of knowledge I have of these so someone please add what I don't know.

 

I don't know about 2 stroke but how did u do your scrolling name at the bottom??????

 

A 2-stroke. . .piston moves down, uncovers exhust port and exhust leaves, at the same time a fresh mixture of fuel has been compressed in the crankcase and it flows through transfer ports to the combustion chamber. Piston moves up covering transfer and exhust ports, compresses fuel (this is when it creates a low-pressure area in crankcase and sucks in more fuel). The plug fires and it starts all over again.
Reeds are not like valves in a 4-stroke. They are between the carb and the cylinder. They're opening/closing helps to create pressure in the crankcase.
Two strokes will make mega horsepower compared to a 4-stroke, but the 4-stroke can make mega torque compared to a 2-stroke.

 

If you seriously thirst for this knowledge, lifted2wd, I refer you to MacDizzy's website, as well as the "How Things Work" website. Both, including their links, provide a wealth of information. Your search engine should produce URL's.

BTW, I believe the oil mixed in 2-stroke fuel's main purpose is lubrication, not flash point adjustment.

Diogenes

 

Yeah, I got so busy explaining the 2-stroke operation I forgot the oil/fuel mix.
Since there is no oil in the crankcase or anywhere else in the engine, the oil is mixed with the fuel to provide lubrication. The crank bearings, rod bearings are ball-bearings in a case, sorta like on a roller-skate. The fuel/oil mix is forced through them to lubricate them. When you see people checking the oil on a 2-stroke, they are checking the gear oil in the tranny/clutch.

 

The name is in your signature email for more instuctions. Here are two of macdizzy's pages. http://www.macdizzy.com/2stroke.htm
http://www.macdizzy.com/cgi-bin/foru...=20&LastLogin=

 

Basically 2-strokes smoke and stink and make an annoying racket, but some guys like them. They're ok for leafblowers I guess.

 

They don't smoke/stink if you set them up right.
I know the noise they make is annoying but that's probably because you just get to follow them.