No, it's not a Japan, UK or Thailand model that I've imported to Canada: it's a regular north american 2007 KLX250S that I've converted to injection.

I assume some of you will find this very intriguing, thus here is the report on that conversion that I promised in another thread. I must admit that I am also very proud of this, so another reason for this report.


First: Why
Where I work, we design custom programmable engine controllers for niche applications. Most of our designs are for industrial applications, though we also have a connection with a performance engine shop and some of our products are used in racing cars and other performance vehicles (quite successfully, btw).

When I bought my KLX in late 2008, I had in mind that it would become an experimental motorcycle for us (we are two in this kind of venture) to make our hands at ecu design for small single cylinder engine. In return for "sacrificing" my KLX, I get the benefit of a fuel injected motorcycle, which is mainly, for me, the programmability part. The fun of this conversion project was also an important factor.

But, I wanted to wait after one riding season before working on the conversion, as I did not have a motorcycle since many years ago and was wanting to ride so much at first. Plus it was my first dirt bike ever. I wanted to taste it before committing to work on it. Thus, the project started around December 2009.

Second: How
Here is the list of components added to the bike (I will have pictures in a further post):
- Fuel injector (replaces the diaphragm and slide in the conventional carb);
- KLX300 header and pipe with WBO2 adapter: I used a wide band oxygen sensor with lambda meter for tuning only, the system works open loop when in use. I remove the oxygen sensor and replace it with a plug when riding in trails, as it is too much exposed;
- Custom designed ecu;
- Fuel pump;
- Adjustable pressure regulator (adjusted to 22 psi presently);
- Atmospheric pressure sensor;
- Intake air temperature sensor;
- Engine coolant temperature sensor;
- It's fortunate that the carb already has a TPS, and that it is not used at all by the CDI (verified on a test bench);
- Wiring;
- Fuel hoses.

Third: Results in brief
- It has been a very lengthy and expensive project, yet very satisfying for me;
- From what I can tell, it works as good as a perfectly jetted bike with a pumper carb, starts almost instantaneously hot or cold, and automatically compensates for altitude, air temperature, and air filter restriction when dirty (to check in the field);
- I've made over 1000km to date with it, 50% in rough trails, with no sign of weakness;
- I don't claim the bike has superior performance to a properly jetted one with the same pipe and air filter as mine (TwinAir). I don't claim the conversion makes sense for the vast majority of you, it does not. Take it as a scientific curiosity only, unless the advantages of FI has no price for you (in which case you would probably buy a fuel injected bike to start with).

Fourth: Various notes
- The fuel injector in stock carb (in place of diaphragm and slide) is only a shortcut: I plan to have a custom throttle body for next year. That performance engine shop I mentioned earlier can design and build it, they are used to it. Due to being one of a kind, it can be quite costly, around $1000, but I will surely go for it;
- The ecu does not control ignition: we also have a cdi in development and I plan to have programmable ignition as well next year;
- The fuel injector that I selected is too big: it flows 4.6cc/s at 45psi, which is nearly twice the flow required by the KLX. This is why the operating pressure is set at a low value of 22psi, so as to optimize the flow time relative to opening time. Even then, I tend to have fluctuations of afr at idle, for example it will drift within the range 13 to 14 while in operation. It is not a big problem, as it is barely discernible. Yet I will change to a smaller injector when doing the custom throttle body;
- I was expecting access to a dyno for the tuning and performance report, but it turned out to be not possible this spring. Due to this, the tuning procedure has been very long and delicate, and I don't have an hp curve to support my performance report. I hope to have dyno access next spring.

Fifth: a few photos coming in next post...

 

The promised photos, along with a few comments:
Custom designed ecu:

It's made of a four layer pcb with components on both sides for miniaturization. It contains a 16bit microcontroller, and interfaces to the sensors/injector through a 23 pin AMPSEAL automotive connector.

It is not readily apparent, but a lot of design effort goes into that small pcb. Lets say it is in the same range as the non-recurrent cost for an oversized fuel tank... It will be used in other products/projects in the near future (it is already, in fact), my KLX project would certainly not be enough to justify it.

Programmability is via an in house developed Windows application.
The ecu is fitted next to the cdi, under the left white plastic. For now, environmental protection consists of wrapping it in a plastic bag. Now that the design is validated, I will potty it in silicone soon.

Injector fitted in place of diaphragm and slide



Notice how the tip of the injector gets nearly flush with the main air stream. As said previously, a custom throttle body is in the plan, but for this year this setup works well enough.

TMAP sensor (contains both air temperature and pressure in one unit) fitted to air box clean side.


This device enables the ecu to know absolute pressure in the air box and air temp, and compensate the injection time accordingly.

Wiring being installed. Looks spaghetti, but don't worry, it is much cleaner after it is finished.


For those interested, here is the wiring diagram:


Oxygen sensor (Bosch LSU4) mounted on exhaust pipe. Replaced by a plug once tuning is finished.


It is connected to a Motec lambda meter mounted on the handle bar for tuning purposes (also removed once tuning is done)


Finished project:

The can extending from under the white plastic is the fuel pump. You can also see fuel lines and a little bit of the fuel pressure regulator over the voltage regulator, under the tank.

Hope you enjoyed! Your questions/comments/suggestions are welcome.

 

Well done!

Sounds like you got it all figured out too, man thats awesome.

I like the sounds of the programmable cdi too! Will that be available for carb models as well?

Great to see choices available instead of always buying new to keep up with technology.

 

RC,

I have the utmost respect and admiration for anyone who can conceive, design and then finally fabricate projects like yours. I also like your charaterization of the project as a scientific curiousity. That is, you took on the project because you could, not because you expected it to be useful for the mainstream owner. Many great inventions have started with the thought " why couldn't I......"

All of the other mods I've seen here seem almost pedestrian by comparison. Please keep us posted on the developement of "Frankenbike", as my curiousity is piqued big time.

No doubt the engineers at Kawi have been down the same road, and while their R&D budget is probably huge they probably haven't found a cost effective way to deliver the goods - gotta make those bean counters happy and keep the Red and Blue hordes at bay on price point.

I for one don't really have a problem with the antiquated technology that allows Kawi to hold the price down on the KLX. Back in the day a rider/driver had to understand the nuances of gravity fed fuel delivery, the need for a choke for cold starts, etc. Almost meant that you needed to understand your particular machine to make it work well. When I think of my late model truck in the driveway I don't miss periodic tune-ups and the tinkering necessary with older vehicles - much better to pop in the key, fire it up and go on.

Which is why I'll continue to look at my '07 KLX as a throwback to 70's tech. Think Richard Petty in STP livery, some assembly required.

In the meantime folks like you will keep improving the breed, and I say keep up the good work

 

very impressive work. This, sadly, inspires way more confidence than the stalling issues that seem to have plagued the factory injected bikes from overseas.

 

That problem is finally getting resolved now that Kawi has quit dragging their feet and admitted that flaws with the Euro model ECU are causing the problem. They are finally stepping-up to the plate and providing new ECU's that correct the problem.

 

Nice job!! Even with your knowledge I'm sure lots of work went into that, I know you guys didn't just Google how to FI your KLX. That's more than just basement tinkering there. I'm sure there were big smiles when it actually fired up. Thanks for taking the time to write it up and post pics.
Dan

 

Thanks for all your encouraging comments. Yes, it was a lot of work... I received applaudishments from my wife and daughters when they hear it fire up the first time in the garage

A programmable CDI might be marketed eventually, but that would be more than one year from now, so don't hold your breath.

 

Good work RayCour! Thanks for posting! Where abouts are you located? I'm in the Vaudreuil area just west of Montreal, I'd love to see how the bike runs!

 

It would have been really cool to see a straight dyno comparison of stock pipe and carb against stock pipe with fuel injection. I suspect there are definitely guys who would spring for a reliable system if the gains were like those of a pumper carb, (plus self adjustment for altitude) and the price was anything close to home. Even the slide swap mount is pretty cool in my eyes. A same pipe comparison would have given a sense of what was available there.

^ I just feel a lot of sympathy for the guys who have gone through months of frustration with their bikes while Kawasaki did the best Texas 2 step around the issue. I know a recall or warrantied item sucks for the company, and I'm sure that there are hundreds of bikes that haven't stalled out once, but it just makes a really bad experience for those riders with a bike that is such an incredibly fun use-able platform outside of that issue. I'm glad it's getting resolved, but I suspect there's more than one guy out there who gave up on the bike before the solution came through. Hopefully now that Kawi is up on it, dealers will follow through helpfully with needed replacements.