much easyer than that, just call tru-turn or email www.tru-turn.com or Dave brown products www.dbproducts.com and get a center drilled and tapped bolt, just tell them what engine and size you need.

most mfg. produce a center driled bolt for there engines so you can use a aluminum spinner, I am not too keen on using a plastic spinner on 4strokes or gas engines.

with gas engines its less critical because most times you don't need a electric starter to get them going, they just flip and rip