My oldest son just traded for a nice 96 CBR900RR on Sat. Yesterday we took it for a 30 mile 1 way trip. We stopped after about 20 miles. When he went to start it, it was very weak & wouldnt crank on its own. We push started it & drove to our destination. When we got there the battery was dead. I swapped batteries from my 98 VFR800, figuring if his bike wasnt charging, he would be ok with my battery to get home & we could push start my bike & let it charge the battery.
With my battery in his bike, it started right up. With his battery in my bike, it fired right up. The connections seemed tight.
When we got home, i checked his charging system out & it showed 13.5 volts & so did my bike. Was it just a bad connection?

 

I would take it on another road trip with his battery to see if it does it again. Sometimes when electrical parts get hot they will break connection internally. Was the bike running when you checked it? This could be signs that theregulator is going bad but I would definitely ride again to see if the battery is dead. Also, was there any corrosion on terminals that you could see?

 

check your voltage regulator rectifier, they tend to go south on these bikes.
i just had a similar experiance this summer but i was more like 400 miles
away from home. i did a lot of push starting until i got home and shortly after that
the voltage regulator rectifier just died. some times my bike would start right up & once it ran for a while and got hot it would not start on its own power and this was with a new battery. good luck

 

I had a regulator issue with my other sons 98 CBR600F3. I replaced his for a no charge condition & about 3 weeks later it died on the same ride we did yesterday, except his wouldnt do anything. It blew the main starter fuse. We trailered it home & i put the old regulator back on it & replaced the fuse it it was ok. Charging good to. I sold the bike & the next day the guy called & said the battery died.
With the 900, i am leaning towards a bad connection or maybe corroded connection, as his battery wouldnt crank his over, but fired up in my VFR right away like a new battery. Weird. I guess i will swap batterys back & clean all the connections & hope 4 the best.

 

if you disconnect the voltage regulator rectifier and look into the plug it may be burnt (bad connection). i just
got a new plug i have not put in on yet but my plug is burnt and 2 of the connectors are black. it might be worth a shot.

 

Either a bad connection or the rectifier is about to bust. I had this similar problem when finally I had to change the rectifier.