Digital Fuel Injection for Chinese 2-stroke motorised bicycle engines

[Fabian]

G'day all

In between doing other things, i was thinking of the advantages of engineering a much better solution to the carburation issues we seem to be having with our Chinese motorised bicycle engines.

I've been looking into Formula 1 fuel injection systems as those engines were spinning at up to 21,000 rpm before they had an 18,000 rpm limit applied to the rule book.
Also, modern fuel injected sports bikes like the Honda Fireblade, Kawasaski ZX-10, Suzuki GSX-R 1000, and Yamaha R1, reliably rev to 12,000 rpm

Since a two stroke makes twice as many power strokes as a 4 stroke and since Chinese motorised bicycle engines rev to a maximum of 6000 rpm, they need a fuel injection system capable of 12,000 pulses per minute.
This is exactly the number we need to make digital fuel injection a real possibility on these small engines.

With closed loop engine management and a wide band oxygen sensor connected to the electronics it would be a set and forget system, regardless of what parameters you experimented with, (different tuned exhaust systems, different intake systems, different grades of fuel ect).

Anybody have ideas that's knowledgeable in this field of engine technology, because i just want fuel injection fitted to my bike.

Fabian

 

[arceeguy]

G'day all

In between doing other things, i was thinking of the advantages of engineering a much better solution to the carburation issues we seem to be having with our Chinese motorised bicycle engines.

I've been looking into Formula 1 fuel injection systems as those engines were spinning at up to 21,000 rpm before they had an 18,000 rpm limit applied to the rule book.
Also, modern fuel injected sports bikes like the Honda Fireblade, Kawasaski ZX-10, Suzuki GSX-R 1000, and Yamaha R1, reliably rev to 12,000 rpm

Since a two stroke makes twice as many power strokes as a 4 stroke and since Chinese motorised bicycle engines rev to a maximum of 6000 rpm, they need a fuel injection system capable of 12,000 pulses per minute.
This is exactly the number we need to make digital fuel injection a real possibility on these small engines.

With closed loop engine management and a wide band oxygen sensor connected to the electronics it would be a set and forget system, regardless of what parameters you experimented with, (different tuned exhaust systems, different intake systems, different grades of fuel ect).

Anybody have ideas that's knowledgeable in this field of engine technology, because i just want fuel injection fitted to my bike.

Fabian

At 6000 RPM, you would need 6000 injector pulse events, not 12,000. The injector would fire every revolution, not twice per revolution. A four stroke would fire once every other revolution.

In any case, I think fitting computerized engine management on a two stroke engine is totally counter to what two strokes are meant for. And that is a simple, inexpensive, and lightweight source of power.

 

[Foximus]

Building a mechanical injection system would be a cinche. And probably work far better than an electronic one ever would. o2 sensors dont like 2cycle fuel.

 

[GearNut]

Foximus is right. The leftover oil in the exhaust will quickly coat the oxygen sensor and cause it to malfunction.
A mechanical injection system would be the only way I could think of to do it.
In the 70's Halborn (or is it Halbourn?) was a popular company that produced such a system.

 

[Foximus]

Take a look at jetski setups. You can get them fairly cheap and would be a Breeze to adapt this onto the billet aluminum intake manifold that guy sells.

Made by a company called MRD. they are on ebay or jetski forums quite often. They make HUGE power all over the RPM range but as soon as you unhook the pump from the water they bog down the motor like crazy. No good for the freestyle stuff I'm into, only big boat racing.

 

[kerf]

It would be much cheaper and more practical to replace your troublesome float style carb with a Walbro pulse carb. On my CY R460, I never have any carb issues, no valves to shut off even with a sealed fuel system that will build pressure. Just a couple of pulls and I'm riding.

 

[motorpsycho]

are you serious?
why bother...the rpm's on these motors are kind of limited because of the gear ratio anyway. (unless you have a shift kit.).
i would think that a fuel injection set up from a 650 c.c. jet-ski / watercraft would supply way too much fuel even with a closed loop set up.
you are only going to get so much horsepower out of these engines because the precision of a high performance engine is not built into these things.
you want power? add an expansion chamber and a nitrous set up. it would be far cheaper than trying to make a fuel injection set up work on one of these things.
contrary to what alot of people think, nitrous oxide will not make an engine blow up. nitrous oxide is not flamable, and as long as you have a rich mixture, the motor will be fine. i have ran several drag cars with nitrous and i NEVER had an engine failure, broken parts, or anything because of nitrous. it's all in the set up, fuel mixture and the tune that will make nitrous work and not destroy an engine.
just my opinion.

 

[Fabian]

Hi arceeguy

I stand corrected - It's comforting to know there are people in here who are a good deal smarter than i am.

What i should have said: 12,000 rpm for a 4 stroke = 6,000 injector pulses, so a high performance motorcycle fuel injection system would be able to meter fuel at 6,000 rpm for a 2 cycle engine.

Thanks for correcting my erroneous statement

Fabian

 

[Foximus]

i would think that a fuel injection set up from a 650 c.c. jet-ski / watercraft would supply way too much fuel even with a closed loop set up.

Actually they are completely tuneable using mikuni fuel jets. Normally youd have a 100 size jet or so... but you could just as easily install a size 30 jet. You can even adjust the fuel popoff pressure in the kit. They really are well thought out, and you power it off the crank, which would be really easy to mod over. Eitherway he asked about injection, and thats an option.

 

[JemmaUK]

Wonderful idea - until the china motor does its usual trick and you get an external combustion engine with an electric fuel pump ...

CH kit $200
EFI kit $150

6 months in the specialist burns unit .... priceless

.... for everything else theres Mastercard....

Why do I have the feeling that burning petroil directed at ones groin is a bad thing... or maybe its just me

Promising idea but just tooooo dangerous with the build quality of these motors.

xx