Motorcycle Repair: Floating Tachometer, straight pipes, battery down

Question
I recently had many problems with my Stock 1998 1200XL, it has straight pipes. It would backfire, stall and not start.

After much research, trail and error, I replaced the pick up/Module, (one piece on 98).

It ran great for 2 days, until... while ridding the tach started to float. I ran the battery down trying to restart it and pushed it 6 blocks. Can I set the timing by ear, light or some other means? Anything else that would cause the tach to Float?
Thanks in advance,

Mike G

Answer
Your tac runs off the negative side of the coil. So if its jumping around then its either a loose connection, bad wire, the tac has gone bad or a short somewhere. Since the bike wont run I would suppect a short which is causing the ignition not to work.
As to setting the timing, the only way to properly time your bike is with a timing light.
Good luck and happy riding
Mike