Motorcycle?

I have a 1998 FZR 600 gneisses With a fully charged battery when I push the starter on weird things happen The solinoide makes a funny sound in that it sounds like one of thoes hydraulic jack hammers that dig up a road I put a screw driver over its terminals and it sparked fine but nothing else Have checked all the fuse and all ok After jump starting the bike I took a amp reading from the battery At idle it showes just over 12v at 100rpm it is 14v At 5000rpm it is 11v so looks like it is discharging I have been told the rectifier is the cause and needs to be changed Any ideas please?