In a word, no.I recently bought a used/rebuilt VRSCA and went through it this weekend to familiarize myself with the bike.
When checking all the hoses from the gas tank, I noticed that there were two hoses that looked like they were at one point connected, now no longer. I pulled out my manual and this is apparently the line from the tank that connects to the Vapor Valve. It looks like the tubing that connected the tank vent hose to the valve is gone and I'm thinking it's just venting to atmosphere instead of the canister.
I read in the manual that "If installed incorrectly, excessive pressure can build up in the fuel tank causing a fire or an explosion resulting in serious injury". I've ridden this thing over 100 miles and the previous owner for 1000s. Is this just something people disconnect from the CA emissions?...
In a few more words, if your bike is a CA model, it will be indicated in the V.I.N. (there will be a "3" after the "HAZ" characters). You'll also have a charcoal canister mounted below the fuel tank.
That vapor valve is found on all models and prevents liquid fuel from spilling if the bike tips over. Non-CA models have a tube running from the fuel tank vent to this valve (P/N for tube is 27378-01) and from the valve another tube leads down through the frame. On CA models this lower tube goes to the charcoal canister and from the charcoal canister another tube heads back up towards the fuel tank top to the purge solenoid and from the purge solenoid another tube goes to the throttle body. (On non-CA models the purge solenoid is replaced with a resistor, P/N 72529-01).
Running the bike without the vapor valve connected won't cause a problem until you drop the bike.