[purplelightning]

There might be more to this than I am aware.. Maybe its a terrible idea but I'll ask anyway...

What would it take on the component level to ditch the CDI box used motorcyle engines. ie drive the coil directly from from the speeduino board? It seems like the Keihin PG-EFI system on some Honda motorcycles does this

[PSIG]

You can trigger either the original CDI box and CDI coil, or an IDI coil driver and IDI coil.

[purplelightning]

Some food for thought for sure and the more I research the more confused I become...

Let me give more context. I'm trying to replace the Keihin PG-FI system that's used on a bunch of different motorcycles. There's no CDI in the system and the ignition output from the ECU is >100v. That said, maybe the coil is a smart coil?

I added some data for reference, maybe there's a clue on the ECU's PCB components.

[PSIG]

Let me give more context. I'm trying to replace the Keihin PG-FI system that's used on a bunch of different motorcycles.

Why you are replacing the Keihin may help for what the project goals are, also helping with how to do it. Alternative source, lower cost, improved or added functions, etc?

There's no CDI in the system and the ignition output from the ECU is >100v. That said, maybe the coil is a smart coil?

In order to replace control will first require understanding what control functions the Keihin provides, and control parameters of the system components. Monitoring the various inputs and outputs during operation may help with this, in a limited way. With two on-board microprocessors I can see, I have a feeling it does more (much more?) than curve timing and react to safety switches. <shrug>

[purplelightning]

It's actually a pretty rudimentary unit from what I understand, dates back to about 2003 and has computing power similar to an Uno.

I'd like to have a standalone ECU that can be used on the myriad to motorcycles that use this ECU. The current option starts at $350 and goes up to about $600 by the time you add AFR controller and other goodies. It's a fine product, but I think there's probably a use case for something a little more cost effective.

It would also be a great base for motorcycle EFI conversions as you can pick components from a bunch of motorcycle models that run the Keihin ECU. Harness, throttle bodies which have injector, IAT, MAP and TPS built in. Some have IAC as well. All be found used (and new) at low cost giving a quick path to that first start.

I added a pinout an some info that I found on the ECU.

[JHolland]

I'd be surprised if its not a 32-bit processor on a 2003, it'll have way more processing power than an UNO, it may not be an issue for you though.
I always advise against using internal ignitors, you are bringing high voltages and big current spikes into the ECU that can lead to big noise problems. External ignitors and cheap and plentiful if you can't find a smart coil to fit.
Do you have enough alternator power to run an EFI? if the original unit used high voltage windings in the alternator then you will be adding a fair bit of additional power draw. On a previous project I had the alternator rewound and replaced the high voltage windings with 'standard' windings to up the power output.

[purplelightning]

I'd be surprised if its not a 32-bit processor on a 2003, it'll have way more processing power than an UNO, it may not be an issue for you though.

I can't say for certain personally either way. I'm just going by what was mentioned in the doc from the gent that made the "fuelino" project. (/edit re-reading the topic, I can see it's hard to see the PDF I attched up above. It references two controllers on the board. One is customer, this is the other: https://www.monocilindro.com/wp-content ... asheet.pdf

I always advise against using internal ignitors, you are bringing high voltages and big current spikes into the ECU that can lead to big noise problems. External ignitors and cheap and plentiful if you can't find a smart coil to fit.

Agree, I'm not thrilled from an electronics standpoint and in a way it's impressive it worked in the OEM ECU. CDI's are cheap (Like $7 cheap), but that implementation wouldn't be a standalone ECU IMO.

Do you have enough alternator power to run an EFI? if the original unit used high voltage windings in the alternator then you will be adding a fair bit of additional power draw. On a previous project I had the alternator rewound and replaced the high voltage windings with 'standard' windings to up the power output.

In the standalone use cases, yes they have enough generator power of course. One project I'm working on is actually a lossless system for competition with short run times. For EFI conversions I'd like to implement PWM fuel pressure control viewtopic.php?t=6325 as an alternative having to find a lager stator.