Motorcycle Repair: Honda cbrr 929 fireblade - non starter, honda cbrr, regulator rectifier

Question
Hi Garry

Id like your opinion on a problem. I was riding my 2002 fireblade home and it stalled. I tried to start and the battery was dead.I bought a new battery as i thought the old one had issues. Two days later same happened. Shop owner said new battery wouldnt charge. Bought ANOTHER new battery - that was ok untill yesterday (2 weeks later) same problem - it starts when i jump from a car battery - but is dead next time i try to charge. i changed the charger under the seat but the new one keeps getting hot, The headlights and all electrics like gauges are working but there isnt any power in the battery to start the engine. Any ideas?

Answer
Ian, The battery may be affected but it may not be the problem. Try a couple of things,first check the output on the battery terminals with the bike off and the battery at full charge. It should be a little over 12 volts. Now start the bike and check the voltage at the battery it should be up maybe 12.5 volts or so. Then bring the rpm up to about 3000 rpm and hold it and check the voltage again you should have about 13.6 volts or so but not over 13.9. If this doesnt show you have a charging problem. This could be a voltage regulator/rectifier going bad or worse case scenerio the chargeing stator. There will be 3 wires of the same color coming oit of the side cover on the engine. Follow it up to the connector and unplug it and test the wires to ground to see if any of the 3 legs are grounded or have a way out ohm reading which could mean that the insulation on the windings is breaking down and may happen when the engine reaches operating temp.