Hi, I have noticed when I crank the engine around, there are some quite impressive sparks flying from the earth point on the engine. Particularly when I try to start the engine from cold, engaging the choke nearly halts it's progress unless the battery is freshly charged. Indeed I have gone to start the bike up only to find that it won't start from cold. I am wondering if it could be a bad earth connection and is thus draining the battery more than it should to turn the engine over. Also I should mention that I have bought a brand new battery and it is still not starting well from cold unless I fully charge the battery before hand.
Dont know about the earthing but that sounds like a logical starting point. In my old Ducati it was a poor starter untill I doubled up the earthing strap (in fact I made the wire run shorter). On my older huskies 450's and 510)they were difficult to start in the real cold. I found that iridium plugs helped substantially.
Shouldn't have any sparking, take apart and clean and reassemble. Usually don't need extra grounds that would be a band aid as it worked fine as designed. Extra grounds for voltage regulator can be a good thing.
Volt drop the earth point. Battery negative with the earth lead earth point with the positive one and you should see less than 0.5 volts. Anymore and you have a bad earth