Wouldn't a "normal" petcock, Off/On/Reserve be better?
Not to hijack but this is related...Leave it in the on position; petcock is open closed by vacuum diaphragm. If it leaks when disconnected then you know you have problem
Without an "Off", how does one shut off the fuel when removing the tank for service?
Good topic for those of us new to the C10.Vacuum operated petcock's were designed as a "safety feature" - engine stops, fuel stops. Supposed to help prevent fuel spills/fires when bike goes down...
How long ago did motorcycles go to the Prime/On/Reserve route on the petcocks?
Wouldn't a "normal" petcock, Off/On/Reserve be better?
Go to mower repair shop. Get $3.50 Briggs & Stratton fuel shutoff. Install. Use.
That will not help. That only makes it worse. The problem is two fold. The main issue is the float valve leaking and the fuel having no other place to go but into the engines cylinders. The manual thing just allows you to leave it on and flowing even more so than a properly working automatic petcock. So lets assume the stock automatic petcock fails and flows all the time, that would be the same as you turning on a manual valve before starting the bike up. It only takes a few seconds to fill a cylinder. The same thing occurs when shutting off the bike. The few seconds it takes for you to shut if off right away (if you remember) is enough to cause hydro lock.
The best option is over flow tubes
With overflow tube you can have a float valve leak and leave the petcock open or have the automatic petcock fail (or turn it to PRIME) and you will know right away when there is an issue and you will not have hydro lock. Fix the problem, do not add to the problem. If you still want to install a manual fuel valve that is fine, but you really need overflow tubes installed or you will still run the risk of hydro lock