Yamaha WR450 - charging system

[forexd]

I got a question on the charging system of 2006 Yamaha WR450...

I bough this bike second hand a few weeks ago. It only had 8.6hrs and done 180km. It never had an oil change, the paint on the frame and the oil drain plug was not broken. The bike looked brand new as well, so I'm 100% sure this bike has only done these hrs.

The guy said he had to put a new battery a few months ago. It was a chinese Kiwi-X battery 12v 6a, just like the manual says.

I took it twice to woodhill, only done 5hrs and the battery went dead, while driving.... the speedo went crazy, was showing random speed of 100-199k/h ( I wasn't going that fast!!!) and when I stopped to check what was going on, the electric start was not working. I had to kick start the bike to get back to the carpark.

Came back home, tried to recharge but it was still dead. Went and got a new Kiwi-X battery from Takapana Hondas. The bike was working great.

Took it twice to woodhill, and the same thing happened about 5-6hrs later. I was hooning on the big sand-dune, 2nd gear, reving the hell out of it, and the speedo went nuts again, elec start not working... came back home, put it on charger, but was dead.

Do you think its the cheap chinese batteries that are crapping out, or something wrong with the bikes elec (don't forget the bike is practicaly brand new)

The manual has 2 elec test to check the charging system, and it was all ok!!!

dont want to spend another $65 on a battery that will last for 5hrs!

[Guided_monkey]

What electrical test did you do??? Are you sure the rectifier/regulator is charging correctly?

Check previous posts for charging system fault finding. Bikes are generally very similar.

[Wired1]

Borrow a multimeter and measure the voltage at the battery terminals with the bike at rest, it should be around 12 volts d.c. Start the bike and measure the voltage across the battery with the bike running, it should measure 14 volts d.c. more or less. If you measure 12 volts or less with the bike running then it is probably the regulator (finned alloy unit a little bigger than a match box). If you measure 14 volts running and well under 12 volts at rest then it's a crap battery.

[forexd]

just picked up a new battery. did the following tests

battery at v12.8 when engine not running

battery at v14.4 - 14.6 when i rev it

the manual also has 2nd test to check the resistance, which i have to do, but need to take the fuel tank off.

So my question is still the same... if the bike is charging the battery, why did a new battery crap out (and couldn't hold any charge) after 5hrs of riding?

Maybe it was just a faulty battery????

[Wired1]

Yes your bike is definitely charging so it's the battery.

[Katman]

dont want to spend another $65 on a battery that will last for 5hrs!

Was no warranty offered with the batteries you've bought?

[Wired1]

Head along to your local battery man and see what they can do for you, a lot of the ones they sell on Trademe are overpriced rubbish and you can often get better quality for the same price. I bought a Yuasa battery for my SR400 a week ago from a proper battery shop and paid $56 for it.

[forexd]

the battery was replaced by Takapuna Honda spare parts team. No problem at all! thanks to them!

I'm planning on heading off to sandpit this weekend, so will keep an eye on the battery. Will test the voltage everytime i come back to the carpark for a quick rest. Did all the electrical tests and found no problems at all.

Fingers crossed...hope this battery will be a good one!!!!!!!

[forexd]

Cooked this one as well...........bugger!!!! after only 5hrs of riding at woodhill

will take the bike to a workshop for a proper test....... bugger!!!!

[Tagit]

Mate this makes interesting reading for me as I am having exactly the same problem on my 04 wr450. It could almost be me telling the story. Just been through my second battery (kiwi) that only lasted about 4 hours each. Bike tested OK at battery shop and was told battery was crap and had internal damage. Took back to bike shop and going to try a 3rd one but of another brand ( don't know what yet) . My bike has no lights or speedo. Its just fine at the start of the ride and dead at the end. Bought bike about 2 months ago with dead battery also. Very suspicious. Will keep you posted. Off to pummis blast this weekend.