Now, first off, many of you technically minded folks will probably dismiss this question as one of the dumbest you have read in a while. For that, I am sorry...I just wanted to ask a thought provoking question.

Because of its supposed threat to the environment, the two stroke engine is fast becoming the newest member of the endangered species list. This is unfortunate because many feel the sensation of arm ripping power generated by a good two stroke engine will never be replaced or duplicated properly even by a well built fourstroke.

So here's my question; is it possible to build a two stroke design that uses straight gas? If not, why? Why can't an engine be designed that fires every revolution and uses straight gas? And has a separate crankcase like the more conventional fourstrokes? Isn't the hangup in fuel delivery? A two stroke has to use the vacuum generated in the crankcase to add fuel to the fire, so to speak, right?

Thanks for your thoughts and your response is appreciated.

 

I'll take a stab..

<<Because of its supposed threat to the environment, the two stroke engine is fast becoming the newest member of the endangered species list. This is unfortunate because many feel the sensation of arm ripping power generated by a good two stroke engine will never be replaced or duplicated properly even by a well built fourstroke.>>

Yes, the supposed threat is there, and believe me that it affects everyone who rides any type of motorcycle from a moped to a goldwing, street or dirt, any type of lawnmower, any marine engine, any personal watercraft, or ATV.

Most of the complaints from the treehuggers/non motorsports crowd/bird watchers, etc..come from the noise level, and fumes (oil residue) of a 2 stroke).. granted while mqaking them more quiet will hurt the performance drastically, and running them leaner (there have been good synthetic oils with great film strenth capable of running a ratio of 100:1 for years, or at least 50:1, ) this does NOT hurt the performance..

<<So here's my question; is it possible to build a two stroke design that uses straight gas? If not, why? >>

the two stroke design uses oil and gas mixed together, when atomized in the carburetor and drawn through the reeds, the oil leaves a film that lubricates the piston, rings, & main bearings..therefore there is no top end (camshaft to control the timing, valves, etc..) The transmission is separate from the crank in a two stroke..
there are ports cut in a piston of the 2 stroke to lube the lower end...& handle the intake & exhaust..not valves like a 4 stroke...so lubricating wise it is a difrent animal, you would have to have a wet sump & give up power to drive that, be able to have a pressurized oil system, & handle the valve timing, & still have the noise issue to make it perform..it is a lot more cost effective to make more effecient 4 strokes than to re invent the 2 stroke..
the big diffrence is the mentality of the buyer..do NOT take this as a SLIGHT..

when a 2 stroke bike/atv/watercraft is bought the emphasis is on performance..that is not the same emphasis whe the 4 stroke bike/cruiser.watercraft/etc..is made for the market..

through performance parts the 4 stroke will perform well..but there has to be a market for this.. on street bikes they will spin 13-15000 rpm..& develop 150-200 hp at the rear wheel..but in a cruiser the rev limit is reduced to 5500 & hp is reduced to 60 or so.. get the idea..the machines are capable of a lot more..

I realize that this is not the answer you wanted, but none the less..what affects a part of us, affects all of us.. I for one believe that just becuase something is a utility/cruiser, that doesen't mean that I SHOULD settle for lack of performance..

 

no way. why?, because its a 2 stroke, 2 strokes dont have a need for oil pumps because there is no valves or cams , they have intake port and exhaust ports so no oil there. the only oil is in the transmission for the gears, the other is to lube the rings and the only way to do that is by mixing the oil in the gas. ................but i could be wrong???!!!@??

 

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Im not an engineer but Ill take a stab at this.I had this discussion w the owner of 1 of the part shops by me.The guy said he doesn think 2 strokes will go the way of the dinosaur entirely,he stated that 4 strokes will rule the roost for a while and right now as we speak the 2 stroke is secretly being developed and rnded to meet these emissions even if we dont know about it.end of convo there basically.My reason is that it wont for the simple reason is that Honda experienmented w 2 motors an efi 1 and 1 that used efi and activated radical combustion that used the spark plug to start and run on top end,the other times the engine was injected fuel and chemically ran on aka preignition like a diesel motor.After combustion was produced it also used a hitech powervalve that not only altered the exhaust port but was a hi tech particulate egr system that trapped and reburned the fumes.Air was the only thing that went thru the bottom end ports if memory serves me right.They even ran it in Baja in 1995-1996 it showed promise and then all the info on these 2 or 3 motors ended.Honda either just wanted to explore or it was too expensive at the time to do so.It put out about 38-48 hp i dont really remmber the exact figure.They also have catlytic converters they used on the rz350 and this technology was back in 1985 to reduce NOx and HC this is old school technology now even tho cars still use this stuff its still pretty hi tech. Last but not least several years back Bimota made a bike called the vdue,I dont remember how many ccs it was or if it was a twin or 4 but I do remember it was injected and had cats on it,fuel was injecte dinto the top end albeit an orbital or fitch injection system and air wen thru the bottom ports and clean air went out the exhaust not the oily residue normally found on a 2 stroke.What simply did that bike in was a midrange glitch they couldnt seem to fix,they went to carbs but I gues sit didnt pass emisions w carbs,plus Bimota wanted 20 Gs for this bike not too many people will pay that for a streetbike.The technology is here its just at what cost.1 more thing dirtbike also took the pipe off the Honda ran there finger in the pipe and said it was cleaner then a 4 stroke an no oily residue like a normal 2 stroke at all.This tells me this engine burnt hot crisp and clean.Im sorry im going on so much but im just as excited as you guys are.I believe motorcycle online has a file and review on this bike.Have fun and enjoy reading the future is here now.[img]i/expressions/face-icon-small-happy.gif[/img]

 

Detroit Diesel used to make a 2 stroke diesel engine. I don't know if they make it now but anyway they would have to discontinue it by October of this year anyway. The Detroit Diesel was refered to as a fuel to noise converter. Not much power but lots of noise. The EPA is really cracking down on large diesel engines like the ones used in semis.By October of this year every engine manufacture CAT, Cummins, and MAC.. and whoever else must have an engine that passes the new emmision standards. They're calling them the '02 engines. The CPSC gave them less then a year to develop engines that passed the tests. What everybody is doing is recycling the exhaust gas by cooling it down and reintroducing it into the cylinders. So far reliability in the prototypes has left a lot to be desired. So now gas mileage and power is gone in the big rigs as well I guess now reliablity will be gone as well. Don't be surprised if you see an increase in the cost of things you buy seeing how now most of the trucking industry's money will be spent on repairing these new engines.

 

IF YOU HOP YOUR BUTT ON YZ 426F YOU,LL NO LONGER MISS THE TWO STROKE 13'500 RPM OF FULL THROTTLE MADDNESS YES THE 4 STROKE HAS SURPASSED THE 2 STROKE AND I HAVEN'T RODE THE HONDA BUT MY SON SAYS IS NOT FAR BEHIND THE 426F THERE ARE SOME WAIT ISSUES BUT I HAVE A KTM 550 THE BADDEST TWO STROKE OF ALL TIME AND MY 426 CAN BEAT HER!!!

PS sorry to get off the subject but a lot of people dont't under stand that 4 strokes have caught the 2's

 

I do understand how two strokes work, that they have no valves, yadda, yadda, yadda...but, I was just wondering IF there was anyway possible to make a motor that combined the best of both worlds.

There are all kinds of experimental motors out there that never see production. They are built for cars, airplanes, motorcycles, atvs, boats, etc... It just seems to me in this day and time there would be a way to do this effectively.

I am a huge four stroke engine fan, as far as ATV engines go, but I am also very respectful of the two stroke engines that set the standards for performance years ago. Standards that four stroke engines have taken much time to begin to catch up with.

Sure, look at the YZ426, CR450F, KTM 520 and some of the other new offerings available to day. Yes, they are great and powerful engines capable of doing mighty things in the right chassis, but look at what they are competing against. Two strokes of half their displacement!!

However, I agree with what someone else said. Why go that route (experimental engine) when you have something that is working so well? Why spend the money on a new engine design when four strokes are making their way?

I appreciate all your responses. As I said, this is only a thought provoking thread. Keep 'em coming!

 

Its called the enviros have gone too far and maybe 1 day when people wake the bleep up theyll drive all of them to china,Cuba and Russia where all of these socialists belong.

 

yep, serves them right..send them to the land of the CZ, & Jawa's.....maybe throw in a ocassional Ural or 2... tie them in a stadium to the seats in the winter & make them watch 2 stroke ice racing....