How did you measure this voltage? Was it line to line straight at the alternator?
Assuming 22 volts is line-to-line, your idle per-phase voltage is 12.7 volts. I'm not sure whether the voltage with the bike on idle should be around 12.7 or 13-13.9 at the battery. In cars it's supposed to be in the latter range, so that will indicate that your alternator might need replacement...soon. But 12.7 on idle should be okay, and as Scottie J has mentioned below, if you rev the engine it should go over 12.7 per phase or around 23-23.9V line to line.