I'm looking for components to add EFI to my 150cc race bike. Some of the newer scooters have EFI and I'm hoping I can use some of their bits on my bike. We have very few EFI small bikes here in New Zealand so parts are difficult to find. Here is my current bike.

In Thailand most people who have a 125 to 200cc race bike, are removing the electronic fuel injection (EFI) because it is difficult to program (adjust) and the extra weight vs benefits are most of the time not in favor of a EFI.

Especially on a race bike you can fine tune a carburetor for one specific fuel and environmental conditions (air-pressure, temperature, humidity) so with enough time tuning you can get with a carburetor a near perfect combustion. An electronic fuel injection with all its digital sensors often not so flexible as a carburetor.

But time is not standing still, as example the new generation electronic fuel injection systems as we now can find on the new Suzuki Nex is actual lighter than a carburetor. So things are changing.... But it would be a lot of work to convert a fuel injection system from a Suzuki Nex scooter to a different engine. Even with all technical data (which is currently not available) it would be a major undertaking, and without the technical support of the manufacturer in technical data and information it would be impossible...

I currently use a GL145 carb which is 30 years old and it's bore small at 22x29. The cam is big, 10 mm valve lift and is 270 degrees at 1 mm. It is still a 2 valve motor. It is producing about 19 hp at the back wheel and runs to 13000. I do have problem however, the bike starts and runs well, however once warm, if I rev the motor, it will not return to idle. It will stay at 5000 rpm. If I am standing still and I slip the clutch and force the motor down to idle, it will then happily idle at 1800 until I blip the throttle again

I have tried 4 other carbs including a 30 mm OKO and all present similar problems. Each carb has had it's own manifold so it's not an air leak. The OKO did produce quite a bit more power at 12000 but was overall was not good.

I have a dyno in my shed and have spent hours with needles, jets and idle jets with no real improvement.

My guess is the late closing of the intake valve and/or megaphone reversion is causing a triple flow through the carb so at 'idle' I have heaps of fuel floating around to keep it idling at 5000.

The extra weight is nothing, The bike is only 74 kg and going to a 30 mm intake will give 2 + hp extra.

I'll make my own electronics, but I need the fuel pump, regulator, injectors, throttle position encoder, MAP sensor and possibly a temperature sensor.

We had in the past contact with an American company that was specialized in carburetor to fuel-injection conversions. The website is http://www.ecotrons.com/ .

I'm pretty sure they can help you with a programmable fuel-injection system (and parts) for your motorcycle. Most modern scooters and motorcycles in Thailand are equipped with fuel-injection systems that are highly integrated, for example the new Suzuki DCP-FI doesn't even have an external fuel-pump and fiddling/tuning is theoretically only possible with a device interface from Suzuki... (Suzuki Thailand not even confirmed that they have such an interface device... so things would be very difficult)

I looked at that page several days ago but was not too impressed. They have motors running but I would like to see a before and after dyno graph with real results. The fuel timing sync is picked up from the spark trigger coil. That does not sound good to me. It is nearly 360 degrees out of phase with the fuel squirt.

Motors can run with very basic carbs. Getting full power out is a completely different option. For one issue, high performance engines have their injectors much further away from the inlet valves than lower reving ones.

EFI is a big step going forward but once learned, it will be much easier next time.

Thanks for your time. It's late here, sleep time now. Cheers.

Hello Marsheng,

maybe this is a good idea to look for and start with: http://www.microsquirt.info/

Some Ninjette-Owner in USA changed their carbs against efi using this system.

Good luck

Thanks I was looking at the Megasquirt but hadn't come across the Microsquirt as yet. Much better size for a bike. Once I find the other hardware I'll probably get a Micro.

While I'm on this topic, any motorcycle wreckers I could contact in Thailand for EFI bits?

Where can I get Suzuki FXR 150 motor spares. Second hand would be great for barrels as we bore them 2 mm oversize. These are the main donors for race bikes. I would really like a few spare cams as we weld these up and re-cut them to race profile. They are much higher performance than the Akunars ones.

The Suzuki FXR 150 is never officially sold in Thailand, but the good news is that the Suzuki Raider 150R uses the same engine. Actually the engine of the Suzuki FXR 150 was also manufactured in Thailand.

Lots of companies in Thailand have spare parts for the Suzuki Raider 150R (FXR 150) engine, I can recommend www.fcciracing.com (the owner speaks English).