[TZ350]

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I have been working on fuel injecting a two stroke. It has been a very steep learning curve. Using an Alpha-N map I can make plenty of power but drivability has been an issue. The racing class rules require one to work with a non competition engine, something like a commuter or farm bike and hand build your own HP.

download/file.php?mode=view&id=3583

A tuned two stroke relies almost exclusively on the resonant action of the pipe drawing air/fuel through the motor and the resonant action and airflow is unstable at low throttle openings so something better than AN is required. Something like Speed Density that responds to changes in airflow.

But the problem with SD is that traditional four stroke methods of measure airflow like MAP or MAF do not respond well in a two stroke. For a two stroke some other method of following changes in air flow is needed. Like measuring the difference between the Max and Min crankcase pressures each cycle and representing that a pseudo MAP value.

I have purchased a complete V4 kit and hope to be able to be able to adapt it to working with my 2T EFI project.

Because most of my interest is two stroke tuning, so as not to clutter up this one with 2T theory I have started a new thread on the F4 F5 (Bucket) Racing forum where I talk about my progress developing my bike and using the Speeduino for tuining my racing 2T. As well as porting and polishing there is a lot of 2T EFI theory there too:-
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https://www.kiwibiker.co.nz/forums/show ... 1131106202

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[TZ350]

A four stroke's turbocharger pushes air through the motor. A two strokes pipe sucks air through the motor. This sucking action is almost entirely responsible for all the air/fuel flow through a highly tuned 2T motor, piston pumping does not do much more than get the engine started.

I have been playing with my new Speeduino V4 and have figured out most things but I am having trouble with engine RPM. I have been sending a 100Hz sine wave to the V4's ignition input which should be 6,000rpm in two stroke mode but I am getting a healthy 4T 12,000rpm.

I need help, what am I doing wrong?

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[TZ350]

Screenshot (40).png (671.02 KiB) Viewed 18836 times

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In Two Stroke Mode a 100Hz should be 6,000 rpm but I am getting a healthy four stroke 12,000 rpm.

What am I doing wrong? ...

[Rocket]

What trigger setup do you use?

[TZ350]

I think you have answered my question.

It is a typical motorcycle trigger, one lump on the flywheel and a pickup coil. So one pulse per crank revolution, 360 deg, and wasted spark if it is a 4T. Not having a multi tooth wheel I selected "Points" in the engine setup and of course points normally would be one pulse per two crank revolutions or 720 deg.

[TZ350]

Could someone help. I need a bit of guidance on setting up the basic Engine Constants and Trigger Setup in Tuner Studio.

My system is a two stroke and has a pickup coil and flywheel with one tooth. Similar arrangement to the picture below.

A single tooth two stroke my not be possible, but if it is I would very much appreciate some pointers about setting up the basic constants in Tuner Studio.

[TZ350]

Found this Aprilia SR50 stater flywheel assembly that should be easily adapted to my engine. 24:1 teeth, I understand how this works so I should not have any problems with setting up Tuner Studio now.

[Yaban]

Men what you try to do is totally useless as a two storke engine act like a pump and the piston displacement control the volume of mixture that go to the combustion chamber.
The only way to let work properly à two storke engine is to have a proper mixture before the engine suck it inside the crank case. Second point crankshaft bearing are lubricated by the oil fuel mixture and I doubt that injectors like it.... You can build a separate oiling system but it's not easy for a engine that have nothing before.
Maybe the only way to run fuel injection on two storke is maf and continuous injection with variable flow to match the airflow reading....
Like a mechanical bosch injection.
You loose your time doing stuff that can't be done.
Efi is the alternative as carburetor for fuel economy and efficiency.....
It doesn't match two storke technology.
Too much stuff are not under control in two storke engine to run efi properly....
Why do you think all motorcycle company give up on two storke engine for for efficiency and pollution reason when a two storke engine is more powerful at same displacement because of the one explosion per cycle.......

[theonewithin]

Why do you think all motorcycle company give up on two storke engine for for efficiency and pollution reason when a two storke engine is more powerful at same displacement because of the one explosion per cycle.......

Because of the way they work they will always be less reliable, less efficient and worse emissions.

Has nothing to do with EFI capabilities. It's just that 2 stroke tech cannot provide what is required.

[Yaban]

Why do you think all motorcycle company give up on two storke engine for for efficiency and pollution reason when a two storke engine is more powerful at same displacement because of the one explosion per cycle.......

Because of the way they work they will always be less reliable, less efficient and worse emissions.

Has nothing to do with EFI capabilities. It's just that 2 stroke tech cannot provide what is required.

Yes because the technology himself doesn't match and accuracy level to deal with a efi...
But about pure performance two storke engine are better than 4 storke......
Men my book before I sleep when I am 10 year old was 2 storke engine tuning and conception. I did motocross supermoto and monobike with yamaha kawasaki honda and suzuki from 50cc to 500cc......
Two storke is the best motorcycle engine but doesn't match the actual level of emissions concerns that's the reason and the only one that made 4 storke engine become the standard in industry....
Ride a 500 Cr honda supermoto in mountain race and you can understand maybe....