Any questions you have before you begin buying, building and installing.
#70403
Good morning. I have a 650cc parallel twin four stroke engine that seems a good candidate for conversion using Speeduino. I'm really only interested in ignition conversion, at least for now. Here's where my thoughts are.

It's a simple 360 degree four stroke OHC motor running a single twin output coil in wasted spark mode. Standard ignition is camshaft mounted points with mechanical auto advance (removed in the picture below). I don't believe I will be able to generate a usable crankshaft signal so I would be using a toothed wheel and hall sensor at the camshaft. I can accommodate a toothed wheel upto maybe 60mm, which sounds a bit small to me and I have no idea about a suitably small hall sensor.

Sounds fairly straight forward to me having read the technical documentation about Speeduino. If anything, Speeduino is way over what is required. But I can't find a system any simpler than the NO2C Speeduino. Hence why I'm here.

Two pictures below. One of the crankshaft mounted alternator, I think getting a clean signal from here isn't really viable. And the other picture is the camshaft end. The camshaft is hollow, has a ~8mm hole right through the centre and I can easily mount a toothed wheel or gear wheel on there. Hall sensor I have no idea about but I don't think it's impossible providing I can find a suitable compact device. Using existing ignition coil, I would have to identify a suitable coil driver which presently I haven't looked at. I think that's about it for now. If I understand this correctly, I only need a signal from the camshaft toothed wheel to give me a workable but simple ignition system. Thanks.

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#70404
FredFlintstone wrote: Mon Jan 06, 2025 10:48 am
I can accommodate a toothed wheel upto maybe 60mm, which sounds a bit small to me and I have no idea about a suitably small hall sensor.
At d = 60 with a 24-1 trigger that would be 7.5deg tooth width then same gap width which comes out to 3.926mm. That's well within reality of most laser cutters. In terms of sensor, I'd suggest making a bushing that would mount to the housing for locating a sensor, and an external mount.

Also don't forget to pin down your trigger disc so that it doesn't move, friction with single center bolt isn't enough. As for igniter you could go for something like a bosch 227.

Here's one I did recently. 1936 Aero 30 with a 2 cylinder 2 stroke:

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#70407
LPG2CV wrote: Mon Jan 06, 2025 4:23 pm Another option is an optical sensor, and the wheel does then not need to be made of a ferrous material.

You configure an optical sensor as if it were hall effect.
Thank you. I had no idea there was such a device. I have been looking at eBay and Autodoc to see if I can find a sensor as small as possible. An optical sensor is something I just wasn't aware of. Thanks again.
#70409
+1, optical sensors are increasing in popularity, mostly because the trigger wheels are easy to fabricate and the sensors are cheap, either factory sensor modules or generic electronic sensors. Various sensor types can read black/white printed paper discs, high-temp 3D printed wheels with slots, holes or grooves, and even round PCBs designed as trigger wheels. Lots of options to easily experiment for proof testing, then a final rugged version for permanent use. 8-) Have fun!

60mm 24-1 optical wheel took about 8 minutes to create, and I'm slow :lol: This can be printed in CF reinforced Nylon or other high-temperature material:
24-1 Optical wheel.jpg
24-1 Optical wheel.jpg (22.88 KiB) Viewed 1398 times
#70410
PSIG wrote:+1, optical sensors are increasing in popularity, mostly because the trigger wheels are easy to fabricate and the sensors are cheap, either factory sensor modules or generic electronic sensors. Various sensor types can read black/white printed paper discs, high-temp 3D printed wheels with slots, holes or grooves, and even round PCBs designed as trigger wheels. Lots of options to easily experiment for proof testing, then a final rugged version for permanent use. 8-) Have fun!

60mm 24-1 optical wheel took about 8 minutes to create, and I'm slow :lol: This can be printed in CF reinforced Nylon or other high-temperature material:
24-1 Optical wheel.jpg
Thank you for the heads up on that. An optical sensor and 3d printed disc looks well worth investigating. I will take a look around to see what I can find in the world of optical sensors. If anyone has a compact sensor they can recommend, that would be great.
#70411
FredFlintstone wrote: Tue Jan 07, 2025 9:19 am
PSIG wrote:+1, optical sensors are increasing in popularity, mostly because the trigger wheels are easy to fabricate and the sensors are cheap, either factory sensor modules or generic electronic sensors. Various sensor types can read black/white printed paper discs, high-temp 3D printed wheels with slots, holes or grooves, and even round PCBs designed as trigger wheels. Lots of options to easily experiment for proof testing, then a final rugged version for permanent use. 8-) Have fun!

60mm 24-1 optical wheel took about 8 minutes to create, and I'm slow :lol: This can be printed in CF reinforced Nylon or other high-temperature material:
24-1 Optical wheel.jpg
Thank you for the heads up on that. An optical sensor and 3d printed disc looks well worth investigating. I will take a look around to see what I can find in the world of optical sensors. If anyone has a compact sensor they can recommend, that would be great.

TCST2103 is the go-to, up to 100C, quite small. I'm personally not a huge fan of optical because the moment any little piece of crud gets on it, your timing is off, and with the kind of discs that people tend to use, warping is not uncommon. Most of which can be mitigated. Sensorwise this is one of the better ones you can get, I've dealt with some ignitions like imfsoft that are super sensitive to sunlight. These TCSTs are quite good in that regard, I've had no issues in test setups running them without an enclosure - though in a clean environment.
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