[JB21]

Hello guys,

i am planning on building a speeduino based twostroke efi controller.

The bike where this should be testet will be a KTM SX 125 2023 model- that already comes with an efi oem.

So everything that is needed for the hardware besides the speeduino is already there.
It uses:
TPS, Crankcasepressure, ambientpressure, IAT,CLT and a VR type CPS.
Map switching happens via CAN- it has a 2 button switch on the handlebar.
The Exhaust power valve is controlled via a 4 wire servo (should be working with TPS/RPM).

The bike uses a 39mm Keihin TB with one injector infront and one injector behind the flap.

The original ecu comes from continental (I think it is a Synerject project from backm in the days- SR50-diTech and so on...)

I am currently tuning the oem ecus- but there are so many variables that affect the fueling and ignition, that you can't really stable tune the bikes to better performance than stock (only 34hp!!!!).
You can make better power with the tunes, but anyways there are some days, where the bikes wont run like you want to.

And the Crank case pressure sensor (CCPS lets call this guy so) affects fueling in a heavy way- I think this is next to tps and rpm the sensor with the highest input in the calculs.
I think it will likely work like alphaN+Map based- but I don't know that 100%.

What I noticed- due engine wear (piston running over 10 hours) the bike looses lots of power- this happens because the minimal pressure drop inside the crank case (blowby). This is way heavier than on a carbed model- so the efi restricts the fuel during the changd ccps values.

So my plan is to implement the speeduino into that awesome riding bike and making it perform better....

I would like to use all the existing sensors- also the ccps, but I am not 100% sure how to handle it in the software site.

For tuning I would install a LSU4.9 and an EGT (where the EGT is always higher rated than Lambda).
The EGT should stay installed and should also be used for safety reasons during failures of the fueling system.

I am looking for any input I can get- this could get a great project!
Thanks in advance for any useful input!

Keep up the enthusiasm!

Cheers

[LAV1000]

About 2 strokes, might take some time.........
viewtopic.php?t=2020

[JB21]

Hey mate,
awesome link! That really helps a lot. I am still reading these- many things, that I already thought about got researched and tested.
I will keep this thread here alive also with my own experiences in developing this.

Thanks!

[JB21]

Okay, so after researching- like I thought:

The map readings from the crankcase pressure sensor will be the ENDBOSS!
The original Mapread in the ini has to be modified to read 2 values per rev and then take the lowest for calculations.

Is there anyone who can help me out with that?

Thanks guys!

[dazq]

Okay, so after researching- like I thought:

The map readings from the crankcase pressure sensor will be the ENDBOSS!
The original Mapread in the ini has to be modified to read 2 values per rev and then take the lowest for calculations.

Is there anyone who can help me out with that?

Thanks guys!

It's not just the ini that would need modification. Actual calculations are performed by the firmware.