Wouldn't it be possible to have a two stroke topend mated to a four stroke bottom end. i'm not talking about doing this. but wouldn't it be possible? Just think about it, not having to premix gas and oil but still having a two stroke. you would never have to buy two stroke oil again.
I would like to hear any comments you have. THANK YOU

 

YES it is! In a way, Detroit makes 2 stroke diesels for semi's (ever herd a older bus or firetruck with that cool hi rev rap sound? The country song "roll on" by Alabama has a 2 stroke detroit in the begenning too) But to keep the crankcase oil from makeing its way into the cumbustion chamber they had to use one exahust valve and a intake port with a supercharger...but it worked well! I personly think they are the best sounding engeine ever built as they rap at 3,000RPM much the same as a strait piped chevy 350 does.

 

It is possible...and I think it even exists. Direct injection should have an oil pump and everything. I hardly see the oil going down to the crankcase coming from the cylinder. It probably exists...it's just more expensive(because it's rare right now), and would rob power (to turn the oil pump).
This should have been the future of 2 stroke. Shame on Honda for having abandoned the exp2.

 

that kind of an engine in.....lets say..... a modern 250R from honda. could you ever imagine the 250R coming out again. honda would make a ton of sales and money.

 

I'm 15 and really interested in engineering. I've been thinking about building a quad like that, but i never knew if it would work. How exactly would the gas and air mix to get in the cyclinder? since they aren't sucked in through the reed valve. Cause the super charger only injects air right? Can someone please help me out, and tell me which two stroke top end, and four stroke bottom end would be the best to use, to build an ultimate high performance quad?

 

At Macdizzy.com they talk about a 5 stroke, 8 stroke and a 2/4 stroke hybrid like you are saying.

 

i couldn't find either of those at macdizzy. where are they located?

 

They are in the 2 stroke section then go down and click for more links and they are about half way down.

 

Whoa boys, IT WILL NOT WORK. First understand how a 2-stroke engine works. The air fuel charge is sucked into the CRANKCASE, where it is partially compressed, releasing a little oil to lube the crank and the lower cylinder walls, then the TRANSFER PORTS open,(right after the exhaust port) as the piston comes down and the partially compressed fresh air/fuel charge is shot into the combustion chamber for the next go round. A 2-cycle diesel engine uses valves and turbochargers (heavy) to replace the simple crankcase compression/transfer port process common to all the rest of the 2-stroke engines the world has ever seen.
I was a motorcycle mechanic at the age of 16, designed and built the first reed valve Yamaha 250 from a '67 DT-1. Reed valves were in common use on small 2-strokes like lawnmower engines not over 125 cc. I used two of these reed valve set ups and 2 Tillotson pumper carbs
attached to the crankcase below the cylinder's piston port intake port. All big 2-strokes were piston port, with some Kawasakis being rotary valve, having a carb right next to the end of the crankshaft, advantage asymetrical intake timing, where the piston port designs were stuck with symetrical intake timing. Reed valves took over once they started making them bigger for the bigger motors. It was really very simple and obvious. But it was not a patentable idea, and I didn't make a buck off it.
Back to the differences though. Ever notice how a 2-stroke crank fits real snug in the case?
That is to raise the compression ratio in the crankcase. When the piston comes down it is compressing that fresh charge that was sucked in when the piston went up. The back side of the piston does as much work as the top. No cams, No valves, much less weight, lots of horsepower. The crankcase compression scenario is kind of like a little supercharger in itself, pumping air/fuel into the cylinder. Live with it, dig it, it's a beautiful thing.
But at least you're thinking.

 

fourlix, Doesn't the pipe on a 2 stroke also act like a supercharger as the Shockwave is timed to bounce back into the combustion chamber at a certain RPM to increase compression and keep the fresh fuel mix from escaping?