is it the battery or the charging system?

[dci19]

I have an 04 cbf 500, it runs fine, doesn't stall. the only running problem is half to full throttle, in this range the bike is lumpy/misfiring, so riding under 6k revs under half throttle, rides fine but bad on petrol, getting about 150miles to the tank, before the problem i was getting around 220-250 depending on how i ride it.

that said, the battery seems to be losing power, press the starter button and the engine cranks slowly, doesn't catch, let go of the starter and then try again, again cranks slowly then nothing, headlight dims. let go and try again, engine cranks then fires up. there was no clicking noise from the selenoid. the head light is dim on tick over, as i rev the bike,the light brightens and as the revs go higher the light dims again.

i have charged the battery up, can take between 20mins to an hour to charge, i have an halfords charger which has a bike setting on it. after charging the battery, the bike starts straight away and loses it charge over five days of using the bike.

i use the bike mon - fri 46 mile round trip and i use it all year round, the bike is left outside covered with a argos motorbike cover.

i have just tested the battery with a multi meter. 12.8v stood, started the bike and the volts dropped to about 7v, then rose to about 8-9v. at 2k revs 14.4, 5k revs the reading was eratic, 5v -10v.

So is this the battery or the charging system, is this the correct way to test the battery and the charging system?

at a loose end tia
mike

[ms51ves3]

Charging system is buggered. Not sure what part, maybe the regulator/rectifier.

[st3v3]

Replace the battery and if the issue persists then replace the entire charging circuit in reg/rec as chives said.

My bike has the same symptoms but I haven't got round to replacing the battery yet. If I use it without the battery then it still happens so the battery is the most obvious fault.
____________________
Roger wrote: Women don't get damp for clingy puppies. Get some better happy pills, hit the gym & buy a medallion the size of a dinner plate. Job done

[FerretFing]

usually anything below 9.5v across the battery terminals when you press the starter means bad battery - you could always take it off the bike & get a bike shop to test it under load - usually for free but make sure it`s fully charged

[dci19]

i dont want to sound ungrateful, but which should i replace? if money wasnt an issue, i would take my bike to a honda dealer.

is there another way of checking the charging side?

would this fault explain bad mpg's?

[dci19]

i will get the battery tested first, then go from there.

i will let u know how i get on

[FerretFing]

Yep, battery first as we know it`s bad from the voltage on startup (7v) - of course, something could be causing the battery to go bad. You could get yourself a Haynes manual & go through the charging system tests - that`s what I`d do after replacing the battery

[Finglonga]

[dci19]

so how do i test the cicuits? i have a multi metre

[st3v3]

Top dollar bet it's the battery. Mine does it, which is also a Honda incidentally. Testing is fine if poss.
____________________
Roger wrote: Women don't get damp for clingy puppies. Get some better happy pills, hit the gym & buy a medallion the size of a dinner plate. Job done

[ms51ves3]

If it was the battery surely this would not cause the lights to dim when the engine is revved.

[dci19]

the battery is ok, just had it checked out at motor world. I put it back on the bike and put the multi meter on it. not started 12.9v, starting 9.7v, 2k revs 14.8v and 5krevs 13.9v?????????

i wonder if the starting motor is on the way out or am i grasping at straws?

is there anything else that could be causing the problem

tia
mike

[ratboy]

you should have a steady increase of voltage as you rev up but as this isnt the case i would suggest that your reg/rec is playing up. higher revs would cause the alternator to create more AC voltage,but if a diode deteriorates in the reg rec it would begin to let through the AC when it has sufficient power. this could be enough to reduce your voltage and damage the battery!
(this is a bit of reasoning on my part and may not be totally correct!)
starter motor shouldnt affect the voltage at 5k revs so shouldnt be that.


tom

[dci19]

just let you know i am getting a new regulator on friday and i willlet you know how i get on.

thanks for all your replies

mike

[finpos]

[dci19]

Sorry for the long wait.

I didnt want to jinx my new battery

I decided to replace the battery as the old one could of been the original, 4years old and is cheaper than a rectifier plus winters here!

I got a gel battery for £38 and my bike starts first time every time.

Thanks to every one who replied

Mike

[Finglonga]

Have you checked the voltages since fitting the new battery to make sure your not going to fry it?
____________________
Andy Sez....
F.Y.Y.F.F.

[dci19]

It never crossed my mind to check the voltage of the new battery.

To be honest its been a good few weeks now and all is fine, when I start the bike, the engine turns a lot faster and catches within 2 secs.

What I have noticed with the new battery is that on tick over the head light dims and when I rev the engine the light gets brighter.

But saying that my car does the same.

thanks

Mike

[prawny1]

Have you checked that your choke isn't stuck on?(could be due to a kinked, frayed or siezed cable)

running a bike on choke past warm up will cause it to misfire at higher revs and hammer your fuel economy.

Not an electrical problem i know but still a possibility.

[Finglonga]

[ms51ves3]