earlwb

customPC, "I also bought the Saito Prop not for electric starter. Can someone explain how to use it."
Ok I see how you meant the spinner nut. Well if the crankshaft is too long in your application, you can use the regular prop nut and then use the spinner nut as the jam nut, and leave the little jam nut off. If the crankshaft is too short, just use the spinner nut instead of both the prop nut and the jam nut. Sometimes you have to leave the prop washer off too.But it depends on the prop, etc that you are using.
A little "Blue lockite" on the threads works to help keep the nut from coming loose. Do not use permanent red locktite though. People also call this stuff "threadlocker" too. Sometimes different brands use different colors, so make sure it isn't permanent threadlocking compound if you decide to use it.

Oh yeah, most electric starters have a reversable rubber insert cone that you can remove and reverse for using with spinner nuts and so on.