Will nanoEFI work with 2-stroke engines?

I have a question regarding viability of this kit on a small 2 stroke engine. I have a modded ~62cc moped. It currently uses a 16mm carb and and has an estimated 5HP at the crank.

Now my question is how difficult would be to adapt such kit on an engine like this ? I’m especially interested in how much power does a system like this draws and if it can even run in 2 stroke mode.

Would be very interesting to see, since small 2 strokes are pretty much exclusively carburated.

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Welcome @hojnikb!

My first dirtbike was a 125cc dual sport smoker. Lots of fond memories.

It’s been a while, so I’m speaking generally. But there’s nothing really stopping the ECU from handling 2-stroke operation right now. There is no distinct 2-stroke mode yet. However, as a quick hack I could remove a couple lines of code to force it to run on a 360° event scale instead of 720°. Not sure how well it would run without additional coding to handle specifics, but the ECU itself is perfectly capable. Official 2-stroke support will come either during or after beta, depending on demand.

Your charging system is the bigger question. If your system can’t produce an extra 5A at idle for a traditional fuel pump, you’ll have to figure out a way to pressurize your fuel within your electrical capacity. There are low-draw pumps available on the market, but they’re extremely expensive. Developing an affordable low-draw pump is something I’d be interested in collaborating on as an open source effort.

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@TravisNano

Thank you for the reply!

Yes, current charging system is a 12V 50W AC system, just barely enough for stock halogen headlights. To top it all off, it’s running either points ignition system or some wierd pointless system, but also doesn’t use any hall sensors. Basically just fires every 180 degrees. I have the latter system retrofitted, since it’s more reliable and with the aftermarket parmakit “cdi” box, it also has some pseudo ignition advance and retard curve.

So yes, ignition and charging system will probably have to be upgraded, machining a gy6-150 kit would probably be the best way to go about it. It would however be a very unique setup, since i’m pretty sure nobody ever tried to fit an efi system to an engine like this.

That shouldn’t be a problem. NanoEFI supports “sensorless” trigger input, in many cases directly from your stock ignition primaries.

I’d want to take a deeper look at your specific ignition setup though to make sure it meets a few criteria to work with the sensorless feature. If so, you won’t need to fabricate in a hall. :+1:

Good idea, you’ll want to take a look at the 11-pole GY6 stator, flywheel, and rectifier combination. The 8 or 6 pole versions don’t produce enough for a traditional pump.

The 11 pole is still a bit marginal for a trad. pump with headlights on. Running a high idle is a rough fix that works, because stator output is directly tied to engine RPM. However, what I’m ultimately going for is using PWM regulation to solve the problem. With PWM control, it should be possible to create a “low draw idle” mode which reduces fuel pressure to a minimal value, and increases injector pulse length to maintain idle with overall lower electrical demand. Still have to implement and test that idea. So much to do!

Yeah, i have to get that whole setup from somewhere (150cc gy6 are pretty much none existant over here due to licenses over 125cc) so that it even fits inside the engine.

PWM regulation would be awesome. As for idle, i’m sure somewhat larger lithium battery could compensate for the higher power draw. You just wouldn’t want to leave it idling for too long :slight_smile:

For all the interested, this is the engine in question
https://bit.ly/3ep9AYR
parts kataloge is in slovene, but should be understandable enough for anybody.

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A few things came to mind related to this:

Does 2 stroke need special injector type ? As far as i’m aware carbs need different atomizers for 2 and 4 stroke engines, does the same apply with efi injectors?

What about oil premix? Would that negatively affect injectors or would it works just fine ?

you can use normal efi injectors with 2 stroke engines. The hardest part is knowing what flow rate you will require. 4 strokes use an accelerator pump basically the only major difference between 2 or 4 stroke carbs… if i understand correctly

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I’ll have to defer to @9wire’s answer on this one as I’m just not as familiar with the details involved with 2-strokes as I am with thumpers. Not a permanent problem though. I’m looking forward to properly digging into 2smoke research! :slight_smile:

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To back up Travis here…injecting a two stroke is not a new function. There are quite a few buts…and if’s…and well, maybe’s. I also have an interest, but wish to complete my four T applications and learn the Nano before turning Travis into gelatin.

It, simply, is not that easy. The short why? You need an airbox…IMO on everything…but you need to understand that tuning a two stroke REALLY connects everything in your system, more than a 4T. For example: a 2T chamber is a fixed piece. You must tune to it, based on what everything else is doing. OK…no problem for FI, but what do you gain for the dinero? Not much. Maybe nothing. Cool, but whatever.

Now…if you can use the Nano to control exhaust output waves? Big shite happens. Travis already has an output that “could” be used for this…but a mechanical beast. Yamaha and Proton and Kawasaki and KTM have done exhaust valve control, (electro-mechanical) but those are located in the head…super twitchy control. Bogging to OMG, WTF…in a nano second.
Now picture being able to control the stinger outlet gas flow…balancing crankcase and outlet gasses. Smoother power, better economy. Can be used with power valve and alone. Not a new concept, but possible.

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:rofl: thanks!

I’d like to see more on this if you’ve got any links at the ready. :face_with_monocle: Going beyond power valve manipulation? Hmmmmm…

More bang always puts a smile on my face!

Just spitballing here, but I have a thought. My Aprilia SR50 2t has a direct injection system which uses a pump located on the rear most point of the engine case to scavenge pressure created in the bottom half of the motor by the piston to drive the direct injector. Could a setup such as this be possible? I am sure it could be done in a more simple way than aprilia did it, potentially just with a brass fitting coming off the back instead of a direct mounted pump

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Interesting, any idea what the peak positive pressure at the bare port might be? If you have any pics, I’d love to see!

Supposedly the pump produces in the range of 60-70 psi. That’s the reading you’re looking for if you’re troubleshooting that pump at least. But that would be more than enough to pressurized some fuel in theory

Oh yeah, that’s more than enough. Is this it?

That is the fuel pump which feeds both injectors. No, it runs 36-40 psi alone but the air pump I described on the back of the engine works to help the DI overcome the pressure inside the combustion chamber. I also forgot, the SR50 is a bit of an odd bird among 2ts because it’s got a relatively heavy flywheel and beefed up charging system to serve the injection system. If nothing else, might be a place to start finding parts to adapt EFI kits to 2t applications! This is the back of the engine, and right in the middle is the air pump.

Sorry Travis and all. It has been 10 months since Travis asked the tough question. I do not have reference links, as we were playing with this as a fun-thing-to-conquer. I lost my father and my Thailand business partner last spring, so my return to the States kicked things sideways.

Let me answer this way: My late business associate was part owner of API Tech in Thailand/Philipines. He was formerly the FI guru for HRC, and well connected in the Honda car world as well. He designed my CRF250L ECU/PCM. Sea level to 15,000’ with aggressive tuning. Fun and phone adjustments, if needed. Covid-19 has greatly impeded development.

What we were looking at with 2T’s was based on some historical features with a modern twist or three. Pipe “tuning” for some Bonneville blasters was done by adjusting the actual pipe length…exotic fuels, huge carbs, scary compression. By adjusting the pipe length as the pressure wave grew, they could sometimes complete a run without blowing the engine. Flatten the wave, giving the seals a chance.

A colleague here suggested that I play with exhaust outlet venturi inserts (in the stinger outlet @ the belly.) This was fun to do and quite easy, really. The only issue is that it works best for a WOT application, like a scooter. At or near wide open all of the time. Easy to change or fine tune. Not so good for a varied throttle or shifting bike.

We came up with idea options to build a tiny rotating valve in an oversized stinger port and use the EFI controller to tune it. Secondly we toyed with an two piece aperture valve, with a fixed tapered cone and a movable one. Inside/out arrangement.

We did test the venturi insert idea, (Sort of) using a simple throttle control from an E-bike. Cheap and easy. (Zero to 5 volt DC) The “sort of” part was using a rotating drum made from an aluminum rod. It was 22mm rod with a power valve like taper, ground to an 18 mm ID max flow orifice. It was inserted into the oversized stinger port with a piece of nylon as an external bushing. The 18mm is a good number for a 50CC 2T.

Sorry, but never got to testing it live on my Honda Gyro engine…but it worked well statically.

Quite interesting. I wonder how the variable air input affects the case pressure? There is pressure from combustion and a wave from the exhaust. Pulse injected as on overlap to both? Many questions…fun!