Hello there,
After a couple of mild/cold days my battery went dead. OK, I charged it and It was perfect. Next morning I tried to start a bike, but the battery was dead again.
I guess I have a battery leak. The battery itself is new and I rode the bike up till now putting 5k on it for just half a year. How can I solve this issue? I checked the rectifier. I have nice around 14 volt when bike is running. Everything seems to be fine except the battery going dead overnight.
Thanks

 

Ok. Since you have 14V when the bike is running I assume that your charging system is working (but not necessary) We'll thirst thing to do is to check weather you actually have a leak. From the 14V measurement I also assume you have a multimeter. Make sure the bike is switched of completely (key out of the ignition)

Disconnect the negative terminal on you battery (Hint: Never disconnect your positive terminal first or when the engine is running. Reason for this is that you could cause a short if your positive terminal touches the body and blow your regulator) Now hook you multimeter up so it's on the highest current scale (usually about 20A on some meters you have to change the probe connections)) Place your multimeter probes between negative cable and the batteries negative. You should measure 0 amps. If you measure anything above say 0.1 there's a large leak. If it's below 0.1 set your multimeter to the next lowest setting (usually 200mA and on some meters you have to change the probe connections) If you measure anything above say 10-20mA (and that's being modest. (Usually 2-3 mA) then you have a leak.

If there is a leak. I'd start by disconnecting the regulator. If the current becomes much lower, that's your problem and you'll probably have to replace the regulator. If that doesn't solve it you have a big job ahead of you cause your going to have to disconnect everything one by one from the wiring harness till the current goes down. I'd start with the ignition switch and then the CDI. Many times it could be a faulty connector that heated up and melted. If your not confident in doing this rather take it to an auto-electrician.

If there isn't a leak then ether your battery is faulty or the regulator isn't charging quick enough but from the voltage you measured I think the regulator is fine.

Let me know what you find and we'll take it from there...

 

Thanks Gerharddvs,
I feel pretty confident with that. Its pouring like hell now here. Will try to do it on weekend and let you know.

 

You need to first determine the source of the leak. First, see if its the battery:
http://cbrworld.net/forums/thread/140473.aspx

If its not the battery, then you have to determine what it is that is drawing current from the battery while the bike is off. Then replace components accordingly.