Hey Mark the starter is the same motor as Boris used.
IT will start anything you want it to with the battery supplied or 12 volts. There is no reason to use higher voltage. inhave been using one for 3-4 yrs.
I have one very similar I made that uses the same motor. 12v is plenty for all engine sizes. I use a 2 cell pack on mine and never have an issue starting anything. The 12v battery on a .21 motor is way to much.
”No it can't.
The solenoid is 12 volt. The motor on 24 volt it would be ridiculous torque and rpm would be crazy fast.
It has way more torque on 12 volt than a Dynatron or a Model 4 starter running with 24 volts.
I think people started using 24v when they were still using gell cell batterys. My standard Sullivan on a 3s 5000 ma 35c Lipo is great. Lots of current there.