Would not start... when hot

Hi folks, I have a question with regards a starting issue...

BIKE - VFR800 20001 FI Y - Rode for about 60 - 70 miles yesterday with the lights on (first hot day @ 30 Deg. C) and bike temp was showing 107Deg. C and I'd stopped for around 10 mins and went to start it again put all I got was a click and a bit of a movement from the starter. All the symptoms of a flat battery. I got a jump start via a car and jumper leads and it started immediately. I then rode home 10 miles with the lights off and parked up with no issues. AFter about an hour I went outside to put the bike in the garage and it started immediately under its own steam. One checking the battery voltage it was 12.5 with the engine off and 14.2 with the engine running.

Q: Would the lights drain the battery sufficiently to prevent starting?
Q: Would the ride home without the lights on be sufficient to fully re-charge the battery?

Rectifier seems OK in my opinion, so what might have gone wrong?

Thanks, Rod

 

I would have the battery load tested to make sure it's actually good. If the charging system is in good working order, having the lights on shouldn't affect charging the battery. While the battery is being load tested, check the wiring harness for any issues i.e. Corrosion on the battery terminals, poor and or overheated connectors , like the one between the Stator and RR. This one in particular is known to cause problems.

I would also perform "the drill" on the charging circuit just to make sure everything is in good working order. If you're no familiar with this testing process, take a look at this thread.

http://vfrworld.com/forums/showthread.php/39277-How-to-fix-common-regulator-Stator-failures/page9?highlight=The+Drill

 

I don't know why, but batteries that are at the end of their life will work fine cold but then won't have enough amps to start when hot. I would check the voltage across the terminals when running (should be around 14-15v with the revs above idle) to confirm the charging system is OK, but mainly I think you just need a new battery. Spend a little time checking over the battery connections and the stator connector too, any sign of corrosion/heating is bad.

 

cheers folks. Nw fitted a volt meter to keep an ee on things. I'll report back after a few rides.
Thanks again.

Rod