Slow crank... no start

[kairles]

Went to go to work this morning and the busa didnt want to start. Just cranked over really slow until it just stoped. I come home to check it out, put volt meter on the battery and it reads 12.44v. I go to start it and same thing, turns over really slow then stops. I jump it with my charger and it starts right up. Check voltage at the battery again and running at idle its bouncing from 13.0v-13.4v. I bring the RPMs up to about 6k and it reads about 14.05v. I had problems with my rectifiers(Im on #3 now) but from this test seems like everything is working as it should. The battery(interstate) is about a year old, and the terminals are nice and snug and clean. Its been about an hour since I jumped it, and its started just fine 4 times. Anyone have a clue what could be wrong? what should I check next?

 

[AJAY]

Possibly an internal short with very high resistance. I recommend charging it, then leaving the ignition on for 5 minutes to bleed off the excess charge. Then shut down the bike and take a reading. Let it sit overnight and take another voltage reading. If the voltage is below 12.6 volts then the system is discharging and you probably need a new battery.

Another thing that folks rarely check is resistance through the ground system. A bad negative ground (where does it ground on the busa, on the engine? on the frame?) will show you good voltage readings, but offers resistance and eats up voltage (potential) when high current for the starter is flowing. To check this, put a volt meter between the negative terminal of the battery and someplace on the engine. You won't read any voltage with the key on but not running or the engine running, but you will see a voltage when the starter is cranking (high current through the resistance of the ground strap and it's connections at both battery and the frame or engine).

 

[06Busaking]

EDIT: What he said.

 

[BIG GUY]

I would go with what AJAY said. It sounds like he may have had this same problem.