how much mileage can i go before i have to do a valve job...and what are the consequences of not doing a valve job. bought rc51 used with 5000+ miles on it...now has 17000 miles...lost the fwd cylinder...50psi...and the rear cylinder is at 110 psi.. one shop guy says that i have bent valves...air coming out of intake and exhaust. any info be much appreciated...v twin (especially rc51) for life.

I find it strange that you would have a bent valve. Bent valves are caused by over-revving the engine, and seeing the RC51 has a rev limiter, it something that really shouldn't happen.
My 24 valve, Honda CBX has 57000 miles with the original head intact! If you ride your bike easily, it is probably a fluke, because the only way you can whack a valve on a RC 51 is by over-revving it, and the valve by inertia, overcoming the valve spring tension, and hitting the piston. The Rc 51 has a gear driven valve train, which makes it nearly impossible to skip time, unless a bearing failed in the gear train. I'm curious, please let us know what caused the failure when it gets pulled down.

john