worb5, it's a 51mm crank with an 1,25mm excentric crank pin which makes for 53,5mm stroke, unfortunately this is a co$tly thing. well, lets say it's lots of work any electric ignition for smallframe will work. On my Malossi engine i run ETS crank, Hp4 flywheel and ET3 ignition I don't know if it's available already. But in any case, if I were you, I would NEVER run a 19mm slim cone crank. difference is only the inner diameter of the crank seal, bearing is the same. ET3 ignition works on every crank there is for smallframes. well, you can't do anything really wrong, you can just build in lots of vibration which can be easily avoided if you take care to remove more material on the upper half (rod side) of the crank than on the lower half. And make sure you leave enough material arond the crank pin area, otherwise the crank will be more likely to twist.