Hoping to get a bit of advice from the teams who have run a Yamaha WR450 engine. I'm scheming to put efi (microsquirt) on one in a bike, not fsae car that's why this is in "off topic"

What did you do for a crank position sensor? Use the stock one? It's only one "tooth" as far as I can see, not sure if that's enough, seems to work on the stock bike though.

Or maybe not, I see a wire on the wiring diagram going from the AC magneto directly to the stock ecu. Directly as in not going through the rectifier/regulator first, is it possible they're using the AC signal from the magneto as kind of a crank position sensor?

What we did (Delft) is lathe the first 20 mm of the outside of the flywheel. Diameter becomes a little bit smaller and the original tooth is removed. Then lathe a new ring, press the ring on the flywheel. Then put the flywheel in a milling machine and machine 36 teeth (one missing teeth) or any other pattern your efi supports. The stock sensor can than still be used.

Hope this helps

Thanks for the response Jetser.

I figured it would be something like that, which is what I was afraid of since I have no mill or lathe.

Anybody else?

How do you know how many teeth are needed?

Guess I need to study up a bit (I was a chassis/suspension guy back in my FSAE days).