Be careful of the "Double Reserve Trick"
Having ridden airheads for the most part since the mid '80's my observation regarding the double reserve trick.
NOT A GOOD IDEA! when you are running at anything more than 3/4 throttle for any extended period of time. The two fuel taps are just big enough to allow for sufficient flow of fuel at high revs. My 1983 R100 had a 336 degree cam fitted with a decent pair of pipes. Used to go really well and 210-220 km/h on the clock was nothing unusual for it. Coming back from Cape St. Francis with a stiff South Easter pushing from behind I just had to see how fast she would go, the needle on the airhead does go past the 220 mark so I guess I was well onto 235 - 240 indicated when she decided to run the two floatbowls dry. Beeing a mechanically sensitive kind of fellow I decided to cruise a bit slower at the 200 km/h mark and all was good. This was with both fuel taps on.
Long Story Short: The double reserve trick is fine when you are ambling along and cruising at moderate speeds, when caning the beast switch to both taps and your airhead will thank you for it. After all it was designed that way. Other point of concern is that with one fuel tap on the "on side" cylinder will get most of the fuel flow with the opposing cylinder may be running lean at times.