2-Stroke Direct Injection. Conversion?

Life Cars & Motorcycles
1

Did Kymco ever actually make the KDI X-Mode 100 scooter for Taiwan?

Here’s the info on the “event” they did for it a few years ago.
kymco.com.tw/tw/event/xmode/index.htm

The interesting part about it is that it is a 2-stroke with direct injection. This means no fuel is in the cylinder until after the exhaust port closes on the upstroke. They use Orbital’s direct injection setup, which means it uses a standard-pressure fuel system with an airpump to help atomize the fuel as it goes through the injector.

The reason I am interested in it is to get some parts from it. Specifically the a head, the injector and the air pump they use to make a low-pressure DFI system.

I have an NSR150 that I have been messing around with a bit, mainly getting it to work as original and to have fun wrenching and riding. I’ve taken the bike half apart and put it back together a few times now, doing a bunch of upgrades and repairs along the way.

In this day and age, I feel a little bit guilty about riding around a carbureted two-stroke. First because carbureted two-strokes are terrible on pollution, and second because carbs are antiquated. But very few white-plate bikes can beat a two-stroke white-plate for power and fun. That said, direct fuel injection two-strokes basically have 90%+ less emissions than carbed 2-strokes, making them competitive to 4-strokes in pollution, and better fuel economy to boot (by maybe 30%+).

To convert the bike to DFI means to go to a standalone engine computer, which also means MOAR POWAH! :slight_smile: Being able to tune the fuel map, ignition timing and powervalve map with a 10x10 on a laptop, and eliminating the restriction of the carb venturi is going to make it much easier to wring power out of the motor. The ECU I would use is a low-cost MegaSquirt-based ECU called a MegaJolt that a friend from Seattle makes and markets.

I’d love to give this a try as a fun weekends project for when the surf isn’t good. There are other sources for the parts, including this USA-based project that converted 2-stroke moto-taxis in the Philippines to DFI:
youtube.com/watch?v=pe5-N5mD … age#t=317s

I figure if workable parts are available off the shelf in Taiwan, however, that would be much easier. :slight_smile: This is more or less a for-fun project but maybe if it makes more power, racers and enthusiasts might be interested in it as well.

So basically the project would be:

  1. Get an NSR head modified or have one CNCed from billet to fit the injector and sparkplug. I can CAD in Solidworks so that’s not a problem, but still need to find a good CNC shop
  2. Fit the airpump and figure out a way to drive it
  3. Fit a trigger wheel onto the motor for the EFI and modify anything that needs to be done to make that work, such as the clutch basket, etc.
  4. Wire up the EFI and calculate a conservative basemap for fuel, spark and powervalve
  5. Get it to run
  6. Find a motorcycle dyno with a wideband and tune it
  7. My oil injection still works, otherwise this conversion would not be possible. Source more pumps or replicate the parts that break.
2

Sounds like an awesome project… Megasquirt also now makes the microsquirt for these type of applications…

3

[quote=“mabagal”]Did Kymco ever actually make the KDI X-Mode 100 scooter for Taiwan?

Here’s the info on the “event” they did for it a few years ago.
kymco.com.tw/tw/event/xmode/index.htm

The interesting part about it is that it is a 2-stroke with direct injection. This means no fuel is in the cylinder until after the exhaust port closes on the upstroke. They use Orbital’s direct injection setup, which means it uses a standard-pressure fuel system with an airpump to help atomize the fuel as it goes through the injector.

…etc, see above…

  1. My oil injection still works, otherwise this conversion would not be possible. Source more pumps or replicate the parts that break.[/quote]

That true?

I wonder if mixing with the fuel in the induction tract helps the oils dispersal in the crankcase. If you separate the fuel and oil, so you are just injecting drops of relatively viscous oil, maybe the lubrication (already poor) would be worsened.

4

[quote=“Ducked”][quote=“mabagal”]Did Kymco ever actually make the KDI X-Mode 100 scooter for Taiwan?

Here’s the info on the “event” they did for it a few years ago.
kymco.com.tw/tw/event/xmode/index.htm

The interesting part about it is that it is a 2-stroke with direct injection. This means no fuel is in the cylinder until after the exhaust port closes on the upstroke. They use Orbital’s direct injection setup, which means it uses a standard-pressure fuel system with an airpump to help atomize the fuel as it goes through the injector.

…etc, see above…

  1. My oil injection still works, otherwise this conversion would not be possible. Source more pumps or replicate the parts that break.[/quote]

That true?

I wonder if mixing with the fuel in the induction tract helps the oils dispersal in the crankcase. If you separate the fuel and oil, so you are just injecting drops of relatively viscous oil, maybe the lubrication (already poor) would be worsened.[/quote]

that may be the project killer right there. two strokes get top end oil lube from the fuel. Dads chain saw with no oil in the fuel ran great, for a little bit. I still remember that beating.

5

[quote=“justreal”][quote=“Ducked”][quote=“mabagal”]Did Kymco ever actually make the KDI X-Mode 100 scooter for Taiwan?

Here’s the info on the “event” they did for it a few years ago.
kymco.com.tw/tw/event/xmode/index.htm

The interesting part about it is that it is a 2-stroke with direct injection. This means no fuel is in the cylinder until after the exhaust port closes on the upstroke. They use Orbital’s direct injection setup, which means it uses a standard-pressure fuel system with an airpump to help atomize the fuel as it goes through the injector.

…etc, see above…

  1. My oil injection still works, otherwise this conversion would not be possible. Source more pumps or replicate the parts that break.[/quote]

That true?

I wonder if mixing with the fuel in the induction tract helps the oils dispersal in the crankcase. If you separate the fuel and oil, so you are just injecting drops of relatively viscous oil, maybe the lubrication (already poor) would be worsened.[/quote]

that may be the project killer right there. two strokes get top end oil lube from the fuel. Dads chain saw with no oil in the fuel ran great, for a little bit. I still remember that beating.[/quote]

Well, not exactly. It’d still be getting oil, I’m just not sure that the crankcase lubrication would be adequate if the oil wasn’t dispersed in fuel.

It also seems to me (though I quite often forget how 2-strokes work) that if you are using the existing oil injection crankcase induction oil delivery mechanism, that the oil delivery is unchanged, so oil is still going to escape when both ports are uncovered, though unburned fuel won’t

You could always premix, injection doesn’t AFAIK preclude that, but the premix will be available for lubrication for a shorter time, and If you rely on it exclusively oil would’nt reach the crankcase.

6

I posted briefly on the Philippines retrofit kit in a “smoky scooter” thread a while ago, and wondered about it for the RZR

http://www.forumosa.com/taiwan/viewtopic.php?f=75&t=83453&hilit=excessive+smoke&start=60#p1155637

Unfortunately, the project was prototyped on Kawasaki 125 “taxis”, and would, as you say, require a custom head, which makes it unrealistic for me , and probably seriously limits the potential of the retrofit idea, though it may pay for “taxis”

If it was possible to design an injector that fit in the spark plug hole, then a more “universal” kit would be achievable, potentially widening the scope of the idea.

Injector/pre-combustion chambers, surrounding the spark plug, have been tested for “lean burn” conditions. The idea is that ignition occurs in the relatively rich injection zone around the spark plug hole, and then a plasma jet or jets fire into the cylinder, igniting the (leaner) remaining charge.

The first ref below shows a cutaway of one of these experimental Injector/pre-combustion chambers. I wonder if something similar could serve as a 2-stroke injector.

Unconventional igniter/injector (“Pulse Jet Combustor”)

http://www.jsme.or.jp/esd/COMODIA-Procs/Data/004/C98_P341.pdf

Pretty (mostly simulated, I think) pictures of Pre-combustion camber ignition and laser spark ignition

EDIT. Sorry, second link is incomplete/broken/hijacked. ENDEDIT

http://www.cd-adapco.com/press_room/dynamics/23/csu.html

7

Ducked, you cannot premix with direct injection. Just think about how it works, fuel is not injected into the bottom end at all. You must oil inject into the crankcase.

Basically, you can look at it as similar to the way a four-stroke dry-sump oiling system works, except the oil doesn’t have a return - it gets sucked into transfer port and burned.

Come to think of it, since you have to run a standalone anyway, it could just have one duty-cycle output to drive an oil injector that’s calibrated to and basically mirrors the fuel injection map… the right amount of oil for the load. This is what the mechanical variable oil injection system like the one on the NSR tries to achieve, but obviously it can be done better with a computer.

Anyway, anyone know if Kymco ever made this scooter? Or better yet, have a parts # list? Thanks! :slight_smile:

8

Of course you can. There is nothing at all to prevent it. That is not to say that it would be sufficient of itself, and I specifically said that it wouldn’t be.

That is EXACTLY what I said above.

My concern/uncertainty, which you ignore, is whether oil injected ALONE into the induction path will be equally effective.

It might be fine (or at least not significantly worse than conventional 2-stroke lubrication, which is pretty marginal anyway). Maybe the turbulence is sufficient to disperse the undiluted oil and get it into bearings etc, but I don’t see that its reasonable to simply assume this, since its quite different to the existing situation, where fuel and injected oil share the same induction path.

It would probably be quite similar to overrun on a closed throttle, say engine braking down hill. Oil injected engines survive this OK (premix ones sometimes seize), which is encouraging, but thats usually a transient situation so it doesn’t guarantee that sustained operation won’t be a problem.

If it is a problem, I’d guess it was addressed in the Philippines project.

9

Think about how this works in a carbed 2-stroke that’s oil injected. Air/fuel are mixed in the carb upstream of the crankcase. Meanwhile a constantly running, crank-driven pump is injecting oil into the crankcase. During the intake cycle of the crankcase, the air/fuel enters the already oiled crankcase. During the intake cycle of the cylinder, some of the oil in the crankcase gets sucked into the transfer port with the air/fuel charge. The air/fuel mixture has no effect on this. The A/F ratio could be 12:1, 8:1 or 1:0 (as is the case with DFI), the oil is still introduced to the crank/bearings the same way.

As for existing DFI setups:

The Envirofit project in the Philippines & India used an electronic oil injector and a separate oil pump. This probably was partially to overcome the fact that many of the bikes they modified didn’t have oil injection to begin with. This also allowed them to control the amount of oil injected based on the load (ie: follows the fuel injector duty cycle). They did thousands (maybe tens of thousands) of bikes like this.

Evinrude E-Tec Marine 2-strokes run in this same basic configuration (albeit with a really high pressure fuel system), and have been for years.

Aprilla makes a DFI scooter that runs like this, and has for years.

And dude, OMG. There is no reason at all to pre-mix a direct injection setup! It’s counterproductive if not outright wrong. The fuel charge never ever sees the bottom end because it is not injected until after the exhaust port is closed on the upswing which is after the transfer port is closed. You don’t put oil in your four stroke gas do you?

10

I was thinking about it the way I believe it works in my carbed 2-stroke that’s oil injected.

As I recall/understand it, the RZR oil injection system is relatively primitive, and does not have oilways injecting directly into the main bearings. Instead, injection occurs downstream of the carb, into the incoming air stream, and lubrication of the crankcase is by the “blown” fuel/oil mixture, hence my concern about undiluted oil in the abscence of fuel.

I’d have a look at the bike to confirm my recollection, but it isn’t here.

If you’ve got oil injection via oilways direct to the main bearings, (as I believe some Suzuki Posi-Force, and apparently NSR’s have), then the concern is much less, though there might still be a question as to whether unthinned oil transfers from the crankcase to the cylinders as efficiently in the abscence of fuel.

11

I haven’t taken the bottom end apart to look for certain, but I don’t think the NSR has oil injection through the crank journal as part of the design. Otherwise, all the guys who are running without oil-injection and premixing would have spun their bearings at a very high rate.

I see what you mean about the fuel “thinning” the oil, but they do call it preMIX not preSOLUTION. :slight_smile: If you leave a premix sitting around long enough, the oil will have settled out of the fuel. The viscosity of the oil is affected by the temperature more so than anything else, and I don’t think it’s necessarily “carried” by the fuel. They are different substances at different densities in a mixture, not a solution.

I checked on ruten and yahoo and it seems there are KDI X-Mode 100s out there, but it looks like they didn’t sell that many. So, cool I know I can get some of the parts. Heck I might just get one of these scooters too if I can find one! That’s a clean-burning 100cc DFI 2-stroke that gets something like 50km/L. Moar powah than a 150 4-stroke and 50km/L? Cool.

12

In this context that’s primarily a semantic distinction rather than an operational one, even if its technically true (and I’m not sure that it is).

EDIT: The fact that “They are different substances at different densities” (ignoring the fact that both components are themselves mixtures rather than single “substances” ) is in no way incompatible with it being a solution. (Nearly ALL solutions would, I think, meet that description.) Nor does it imply that the mixture will be inhomogenous or unstable (water and alcohol, for example, forms a stable mixture). Nor would it necessarily matter a damn if it was inhomogenous or unstable. ENDEDIT

Even if its a fuel-oil mixture/emulsion, rather than a true solution, the mixture may still be operationally desirable/necessary, so its a moot point.

You know that for a fact? Never heard of anyone having starting difficulties because their oil had settled out, and if you had to leave it for a very long time to show the effect it’d be very hard to distinguish from fuel ageing.

I don’t either, necessarily. I think that, in the abscence of definite evidence to the contrary, its a (speculative) possibility that it would be prudent to bear in mind.

Yes, that is interesting

13

I’ve considered it. I’d call it Upper Cylinder Lubricant.

http://www.forumosa.com/taiwan/viewtopic.php?f=75&t=89668&hilit=Upper+Cylinder+Lubricant#p1171482

The main reason I havn’t tried it on my car (apart from the slight cost involved, and the near impossibility of detecting any benefit), is the requirement to pass an emissions test twice a year, which might be compromised. If my fuel tank had a drain plug (like my Nissan Sunny did) then I’d be more likely to give it a go. Likewise, if I had a four stroke motorcycle.

14

If the oil is being injected into the A/F charge, that’s oil going into a fast moving mist of 6-11% fuel by mass at a ratio of 1-5% oil per part fuel, or 0.06%-0.55% oil per part of the total charge. That’s when you look at it by mass.

By volume, air is 1.22521 kg/m3 and gasoline 719.7 kg/m3 so another almost 3 orders of magnitude difference…

So basically… that’s like trying to hit a grain of dirt on a semi-random place on a target with a shotgun… where the target is 100,000x the size of the grain of dirt. The shot could be made of pure iron and the piece of dirt could be made of a strong strong magnet. You’re still probably going to miss.

While your idea of “upper cylinder lubrication” has some benefits that make sense hypothetically, the varnish that 2T oil leaves behind is going to cause some issues. Think about your valve seats, for one. Your catalytic converter and O2 sensors for another. Your MAF and entire intake track for yet another.

Piston bottom oil squirters get the job done with regard to lubricating the piston walls. Here’s a set from an aluminum block BMW M52B28/S52 Frankenstein I put together as a 10.3:1 boost motor for an M3 that I used to race. It ran a water-to-air intercooled Opcon Autorotor at 11psi and made about 400-450hp depending on the fuel. The piston squirters helped with both cooling the piston and lubricating the cylinder wall.

15

[quote=“mabagal”]If the oil is being injected into the A/F charge, that’s oil going into a fast moving mist of 6-11% fuel by mass at a ratio of 1-5% oil per part fuel, or 0.06%-0.55% oil per part of the total charge. That’s when you look at it by mass.

By volume, air is 1.22521 kg/m3 and gasoline 719.7 kg/m3 so another almost 3 orders of magnitude difference…

So basically… that’s like trying to hit a grain of dirt on a semi-random place on a target with a shotgun… where the target is 100,000x the size of the grain of dirt. The shot could be made of pure iron and the piece of dirt could be made of a strong strong magnet. You’re still probably going to miss.
[/quote]

So you’re arguing that there’ll be too little oil to have an effect. You could well be right, I dunno. I suspect you don’t either.

If 2-strokes didn’t exist and someone had dreamed the idea up in a pub discussion, I’d have said there’d be far too little oil to have an effect, and it wouldn’t work. The viscosity of fuel-thinned 2-stroke oil must be essentially zero, after all.

But it works, sort of.

[quote=“mabagal”]
While your idea of “upper cylinder lubrication” has some benefits that make sense hypothetically, the varnish that 2T oil leaves behind is going to cause some issues. Think about your valve seats, for one. [/quote]

Hang on, you’re arguing that there’ll be too little oil to have an effect, remember? I suppose you could invoke SOD’s Law to answer that one, though.

Re valve seats, could be, but I’d suspect the exhaust at least will get burned clean. Maybe the intake valves might show a problem IF you aren’t injecting directly, and if you are maybe the injectors will gunge up.

However, as noted in the original thread, people do do this, and at least one senior tech. at Silkolene has endorsed the idea.

[quote=“mabagal”]
Your catalytic converter and O2 sensors for another. Your MAF and entire intake track for yet another.[/quote]

:roflmao: VERY hypothetical. I don’t have any of them (except possibly the latter, if you mean “intake tract”). I think we are thinking of rather different vehicles.

[quote=“mabagal”]
Piston bottom oil squirters get the job done with regard to lubricating the piston walls. Here’s a set from an aluminum block BMW M52B28/S52 Frankenstein I put together as a 10.3:1 boost motor for an M3 that I used to race. It ran a water-to-air intercooled Opcon Autorotor at 11psi and made about 400-450hp depending on the fuel. The piston squirters helped with both cooling the piston and lubricating the cylinder wall.

[/quote]

I think we are thinking of [strike]rather[/strike] very different vehicles. :slight_smile:

16

I’m not arguing that there isn’t enough oil. I’m arguing that the distribution of fuel in the air/fuel mixture by volume is so little that it’s essentially all air that the oil is getting injected into.

A very rich 8:1 air fuel mixture is 11% fuel by mass. 11% * 1.22521 kg/m3 / 719.7 kg/m3 = 0.0187% by volume fuel in the A/F mixture. Even if we take into account a 10:1ish bottom-end compression ratio and consider the fuel non-compressible, we’re still talking at 0.187% by volume fuel in the A/F mixture at fully compressed state.

That’s all I’m saying. No need to complicate it any further.

17

[quote=“mabagal”]I’m not arguing that there isn’t enough oil. I’m arguing that the distribution of fuel in the air/fuel mixture by volume is so little that it’s essentially all air that the oil is getting injected into.

…(see above)…

That’s all I’m saying. No need to complicate it any further.[/quote]

Don’t think I did. I probably wouldn’t know how. Your argument sounds very reasonable.

BUT as above, I think you could apply essentially the same argument to show that 2-strokes can’t work, Bumble-bee stylee.

Re downside, I’d say the most serious obvious possibility is that the rings gum, and that’s probably enough of a potential pain to make it not worth trying, on a car anyway. A more easily stripped, (and highly stressed) motorcycle engine might still be worth considering.

You could possibly address some of the downsides with water injection/ingestion, another potentially fatal attraction.

18

That very little oil is needed to lubricate a 2-stroke bottom end is an independent discussion from whether or not the oil injected into the air/fuel stream is significantly or at all “thinned” by the fuel.

19

Hmm…One could discuss it independantly if one wanted, but that seems to be an artificial separation, obviously so in the case of premix.

I’ve read somewhere that when two liquids of different viscosities are mixed, the viscosity of the resulting mixture is not a simple arithmetic mean of the components, but is heavily skewed toward the viscosity of the thinner component.

20

Dude this is ridiculous. You were talking about injecting oil into the a/f stream on what you call a “blown oil injection” setup versus injecting into air only and now you are going to bring pre-mix back into this? Just stop. It’s an obvious troll…