Hey Bill,
That Cowpuc, he's a gem! The only thing I wanted to add is that we have a member on the Forum, Dano that at one time machined a 6 sprag Starter Clutch. (Heavy Duty) If in fact he no longer offers that upgrade, I offer one. (But I would prefer that you check with Dano first!) The stock Yamaha Starter Clutch has 3 spring loaded "Pins" called sprags that engage and connect the starter motor to the engine during start up. With the Heavy Duty unit, you have 6 spring loaded sprags instead of 3, and this distributes the engagement load over 6 pins instead of 3. The failure point is actually the housing that holds the pins, so by adding more pins, you decrease the load on the housing in any given area. Pin spring failure is also another area that causes a starter clutch to go out.
Cowpuc is spot on about the maintenance of the starter motor and the use of a GOOD strong battery. The sprags of the starter clutch engage due to centrifugal force, so if the battery is weak, or the starter is dragging because of dust from the brushes, the you don't get FULL engagement of the starter sprags.
Only the model years 1991, 1992 and 1993 of the MKII Venture and Royale came with the 4 brush starter. ALL second Gens. came with a 4 brush starter.
I hope this starter info helps you Bill, and Good on YOU Cowpuc for sharing your vast knowledge of these wonderful motorcycles with a fellow member!!
Earl