ok so after college on friday i rode into town with a few mates on the bike after about 10mins of stop start, the starter motor started to sound a bit underpowered and the next time i tried to start it it didn't, we bump started the bike (its well easy on the v4 isnt it),

so I rode to work (halfrauds) to get a new battery, couldnt get the same one so i got one slightly bigger (taller and a little more power is this ok), now it starts fine but i put a mulit meter on the new battery to check it was charging, at tick over it was at 12.5 volts and when i reved it to about 5k the volt reading increased but only to around 13 volts,

does this mean the regulator is on its way out? or was the problem indead the battery and the problem should be fixed?

when you were riding the bike with your mates did you have your lights on?
im guessing your alternator is on its way out.......the charge rate seems to be a bit low especially at 5000rpm.
it should be between 13.5 and 15.5 volts.
i had a similar problem and if i didnt use the lights the battery would get a sufficient charge but if i used the
lights it would drain faster than what it was getting charged.
you would be better using a correct battery and if you still have the old use it once you find the problem.

I think it should be 13.8v @ 5000rpm. My aftermarket one gives 14.2v @ 5000rpm.

I'd suggest using the proper battery..

http://www.tayna.co.uk/" onclick="window.open(this.href);return false; are cheap & deliver quickly...

Make sure the +ve & the earth lead are connected properly.

Tests for the generator & reg/rec are in the service manual, easy enough to do if you have a multimeter.

hey spike.

I recently had a problem with my battery going flat all of a sudden. After doing a lot of research I decided to fit a 2003 yamaha r6 reg/rec. My voltages are now up to a consistant 14.5 - 15.2 volts and the bike seems better for it also. A well worthwile and cheap upgrade in my opinion.

cheers for the advic but im pritty sure mine has an uprater speedo already, here's a pic fit:



(bit out of focus )

Sounds like the classic burnt out reg/rec symptoms to me. The larger battery is fine (lemme guess, a YTX9-BS?) Check the connector block on the loom side, it might be a bit 'toasty'. Get a finned reg/rec and you'll be 'reet.

nah it was an 8 something, does any one know what regulator that is then, will the conector be the same for all reg's,
how much am i looking at then? (as im soo broke it not even funny :D )

It doesn't look like an OEM one to me but it still doesn't have much in the way of cooling fins either. Have you checked to see what voltage the reg/rec is outputting and also what voltage the connector blocks are outputting on the other side of the bike? As viper said, the connector block on the loom side is prone to getting old and stiff and can sometimes burn up a little which will effect the voltage the wires are carrying.

My money is on your reg/rec though as your symptons sound similar to mine. Problems is that if you are only getting 13v at the battery at 5k when you put your lights on it will lower the voltage significantly. This will eventually ruin your new battery as it won't be charging it.

Any yamaha r6 2002-2004 unit will work. Should be able to pick one up for about £30 off ebay.

The r/r looks like a Honda unit alright, but from a CBR600F. If you get in touch with Rick Oliver for an uprated r/r that'll do the job for you. Plug and play and no need for cutting wires etc