HOPE FOR 2 STROKES!

[2T Institute]

Have you had a 2-stroke with water cooling? With a variable exhaust port? With electronic ignition? All these are "modern" enhancements of the basic two stroke design and non of them take away from the need of an expansion chamber tuning the exhaust pulses to shove more fuel air mixture back into the combustion chamber before the exhaust closes.

NONE of that changes with DI. The method of bringing air into the cylinder remains the same. Up stroke sucks it into the crankcase, downstroke pressurizes the case and then shoots the air up into the cylinder as the transfer ports open. NOTHING DIFFERENT HERE. Only difference is there is not any gas in that air in the crankcase (side advantage here, no gas washing away any lube oil in there so don't have to use as much!).

Except the decending piston doesn't 'shoot' gasses into anywhere especialy when the transfers open, only problem with 'dry' bottom ends is the lubrication issue(how do we get the oil to where it's needed) and the that fuel cools the metal. Water cooling has been around since the 1920's , only thing that doesn't change is the  fact we have yet to see a single working example of a full size DI motorcycle. The DI/injected KTM300 rumor is about 5 or 6 years old now.

[Kodackamera]

Perhaps a reworking of the posi-lube system from around the 60's.

Hear what I'm saying, variable geometry doesn't have to be so widely variable, powerbands are still attainable, the most highly tuned engines are rarely the smoothest.

When D.I. gets started, it's not going to be perfect, or what people want, instantly, we have to allow something to ACTUALLY HAPPEN. What a shocking idea. Revolutionary in fact.

Why would they get all super performance and focus on horsepower firebreathers until they can get the commuter scooters just right? Think for a minute.

The performance will come.

[VintageBlueSmoke]

@Suzuki DS250/185,

We all hear what you are saying. A simplified, affordable 2 stroke motorcycle that any 'shade tree mechanic' can repair would be nice and our 'holy grail'.

Yet, thanks to environmental issues - real or imagined, lawmakers from around the world are looking at all forms of pollution and ways to minimize and eliminate it. 2T's by nature are filthy animals and can easily be replaced with 4$, albeit of larger capacity, that run cleaner and more efficiently. The US government has actively pursued tackling global pollution in other countries as a way of cutting the total green house gasses rather than taking the economic hit in this country. Elsewhere in the world, the 2T is a measurable problem and easy to eliminate. All that said, motorcycles are only a small part of the 2T emission problem.

The trick for those that love the 2$ and think it is a superior design, have to come up with a solution to make it run clean and have a more efficient use of fuel. Evenrude and Can-Am (and sounds like KTM) believe that DI is the answer. John Dear bought a 2T design from a friend of mine for their Lawn and Garden line (though I have not seen it). I'm sure other manufacturers have it on their R&D plate. Change is going to happen not because of '4$ like power bands' or 'easier to ride' motorcycles but because the market and governments DEMAND clean and efficient vehicles.

You and I might not understand DI or the computers required to run it, but the future 'modders' will. You and I understand carbs but our great grandparents probably had no concept and what was under the hood was just as alien.

I, myself, am looking forward to their offer and if Can-Am came out with a DI 2T with electric start, I'd buy it today.

[citabjockey]

If I could get away with a 1.8 gallon tank to make a 25 mile loop at the virginia city grand prix instead of packing another 4 pounds of gas with me, that sure seems like an advantage to me! How hard is it to loose 4 pounds off a bike? How about a full day of trail riding with a 3 gallon tank instead of 4? I would not call 30% tiny.

Like it or not two strokes are a very endangered species. I for one would be very happy to see a modern bike with a CA green sticker on it (so I can ride it year round). I already have vintage two strokes (Yamaha MX125, RT3, CT3, SC500) and love them BECAUSE they function great with no water, no power valves and not a single transistor -- for 2 of the bikes anyway -- but they are pretty brutal to ride fast.

I love these engines but the writing is on the wall. DI is the only way to continue the breed in today's world. Not only continue it, but to improve two strokes as well. A 600 SkiDoo makes over 100 HP, thats a 50+ HP 300 single. Not too bad. My SC500 only makes 38 HP and I can't open the throttle all the way for more than a couple of seconds. Had a WR500 a decade or two ago (YZ490 engine) and could not open the throttle when on the pipe on that bike for very long either.

No DI equals a dwindling choice of bikes for us in the future. That's a future I would like to avoid.

I too am waiting for final validation of DI on bikes -- seems like all the parts are there but one has yet to show up. maybe this is political games by the manufacturers or maybe there is some other technical hitch (like getting that injector to work right while banging over woops) but it does concern me that one has not been offered so long after DI has been available on boats and snowmobiles for so long...

Again, as a message to KTM, Honda, Yamaha, GasGas, TM, etc, I will buy one the moment it comes out (then duck when my wife finds out! )

Yes, but that 30% might be important to you. It's not important to me. I don't care at all if a little tiny bit of the fuel charge is lost here and there. All I care about is how the bike runs.

When my bike runs out of gas, I put more in it. If that happens 30% sooner, I don't care.

[Chris2T]

For those afraid of modern electronics/direct injection neutering their beloved 2 strokes, please go to youtube,type in "Ski-doo 800 etec wheelying" and browse some of the videos.

Then come back here and tell us all how neutered, easy to ride, and 4 stroke behaving they are. sheesh   

[ACMX]

Chris, maybe it's not the performance some people are worried about, but perhaps the atmosphere. It's some of the worst things about dirtbikes that we love the most. For example; the sound. There's no way around it, it's LOUD... But we love it. The blue smoke... We know it's not doing any good for the environment... but we love it. Put too many circuits on a bike and it becomes an electric motocross bike. Say good by smoke. Goodbye wonderful sound. Hello wall charger. (I'm talking long term of course... but my point still stands)

[CCOADY454]

only problem with 'dry' bottom ends is the lubrication issue(how do we get the oil to where it's needed) and the that fuel cools the metal.

Dry sump oiling system SHOULD work, but then again would need a reservoir tank, cooler and oil pump and complete engine re-design.  HELLO 15 more pounds.

[TMKIWI]

An electric solenoid oil injector weighs 1 lb & and the feed hoses nothing. Same size hose as your carb overflows.
Oil tank weight will be what ever the bike needs.
For example a enduro bike doing a GNCC or a 4 hour race would need 800ml's of oil.Depends on what oil rate they would use.
A MX bike would need a lot less.
So the weight penalty would not be too great.

[citabjockey]

Agreed. Again, the alternative is valves, cams, chains, rockers, tappets, keepers, guide, seals, etc, etc, etc. I'll take my oil injection and enjoy it thank you! 

An electric solenoid oil injector weighs 1 lb & and the feed hoses nothing. Same size hose as your carb overflows.
Oil tank weight will be what ever the bike needs.
For example a enduro bike doing a GNCC or a 4 hour race would need 800ml's of oil.Depends on what oil rate they would use.
A MX bike would need a lot less.
So the weight penalty would not be too great.

[CCOADY454]

Agreed. Again, the alternative is valves, cams, chains, rockers, tappets, keepers, guide, seals, etc, etc, etc. I'll take my oil injection and enjoy it thank you! 

I like a rule change alternative better.  The 2 stroke would benefit more from that at the pro level than anything.  THEN others will follow KTM and implement chassis improvements if they bring back their smokers.

[citabjockey]

I am all for a rule change too (just signed the petition). There is no reason to have the two stroke 250 struggle against 450 four strokes. They changed the rules to make things more even before -- they can do it again. DI is not necessarally a path to significantly more performance. Its main purpose would be to get 2-strokes on the trail (and maybe on the street) so that manufacturers could again build boat loads of them. Economies of scale will allow low build costs which boosts profits -- manufactuers take note! An $8k two stroke offroad bike has got to have more profit in it than an $8k four stroke given the same running gear -- well maybe less profit in replacement parts sales... some might say that's why we are in the the current situation...

I like a rule change alternative better.  The 2 stroke would benefit more from that at the pro level than anything.  THEN others will follow KTM and implement chassis improvements if they bring back their smokers.

[factoryX]

why not seal off the crank bearings and let them be lubed by the tranny fluid?

[citabjockey]

You would still have to arrange for oil to get to the piston skirt and the crank and wrist pins so still need some sort of injector, but yes -- does seem like the crankcase halves could be setup to have you install a seal onto the inside side of the case, put the cases together and then press the bearings in from the outside. Downside is that you would need to split the cases to change those seals.

why not seal off the crank bearings and let them be lubed by the tranny fluid?

[maicoman009]

 I personally like the idea of direct injected 2-strokes for many reasons. The 1st is to keep the "green weenies off of our case!" The 2nd reason is to get 2-strokes back out on the MX & SX tracks and a 3rd reason I would like DI 2-strokes is because it imo would NOT effect the overall power in any negative way.It may however smooth the powerband out & give the 2-stroke much better traction to compete with the 4-chokes & I of all people am NOT really enthused with the electronics that would be needed with the direct injected 2-stroke & for that reason I would like to see the manufacturers produce both direct injected 2-strokes as well as carbed smokers for all of us to have a choice! Although with that said I would still be very interested in a direct injected 300cc. 2-stroke for offroad riding as well as street legallity to be able to ride to the trails & offroad places I ride.
  The last thing I would like to mention is just like the 4-chokes & thier fuel injection a 2-stroke with direct injection could & would have several different map settings so it could be programmed to the riders preference & I personally do not think that DI would really effect the powerband all that much that it would take away the fun factor that all of us 2-stroke riders love!........................... The so called Shock & Awe of a hard hitting & wicked 2-stroke powerband!!!!

[citabjockey]

Ok, here is a wild thought for us that don't want the computer dictating the bike's behavior. Have a USB (or even bluetooth!) port on the DI computer and the manufacturer can give/sell you software that would present a bunch of knobs - a knob that looks like a needle clip position, a knob that looks like a pilot jet, main jet, a power valve, etc. Maybe a timing advance curve you can drag around, shift the injection timing, the list is endless!

Of course the moment you take any of these parameters out of the manufacturer approved envelope the warranty goes poof!  This would make the bike just a tune-able as existing bikes but the changes could be done in seconds and would require no wrenches. Could be very cool!