Bike running like a bag of shit

[KiwiNC21]

I guess you've got this sorted already but sounds to me like you've got a cooked regulator/rectifier.

Caused many-a-headache amongst VFR400 owners.

[wullvfr]

because the battery is getting charged then the reg rec is working,at idle 15 volts usually indicates that it is no longer regulating which normally in the end up frys everything but in your case the voltage does not rise when you rev the bike....

the manual states that @5000rpm the charge rate shold be between 13.5-15volts....

yours is within this range..........

william

[1990nc30]

Hi, i still don't have a clue whats wrong with it but i know it's not the battery or the reg/rec. The alternator resistance between those three pins in the little box by the right knee seemed fine. I still think it's the alternator though, i read in the manual that even if there is continuity between the three pins it could be the alternator stator coil assembly thats at fault and if so needs replacing!? I bet the alternator has never been changed and it is an 18 getting on for 19 year old bike so i'm sure it must be getting tired now. The only thing is, i don't just want to buy a new one and fit it and still have the problem, but i don't want to shell out aload of cash for someone to tell me what it is (stingy i know, lol!) i'm going to have to do something though coz i can't carry on riding when the bikes like this!
Cheers guys!

[CMSMJ1]

Well..take the side of the engine off and see what the altenator looks like... It drips a bit of oil, but not a lot...

It is knackered...there is no two ways about it! If you get continuity then something is not right.

*looking for a tasty alternator pic*
EDIT



This was mine....

[1990nc30]

If you get continuity then something is not right.

Sorry i meant there was no continuity between any of the terminals and ground (earth)
which made me wonder how it could be the alternator!
Cheers.

[1990nc30]

CMSMJ1,
If i took the side of the engine off, would i need a new gasket for when i put it back on?

[CMSMJ1]

Yeah, normally - but if you take it off and the alternator is knackered...then you need a gasket anyway.

I would say it is worth checking just to rule it out

My bike ran OK with that scabby generator in it - it would go fine until you had the lights on and then it was a race to get home before the battery died with the associated poor running like you describe. I had already replaced the reg/rec and the battery and the white plug from the generator end. Whole lot was goosed...

IIRC the gasket was fairly cheap (as far as Honda Gaskets go)

See if Rick Oliver or Graeme France can sort you out.

[1990nc30]

CMSMJ1,
Did you do the checks with resistance of the three pins in the little white box by the right knee (the check you told me to do) if so did it seem fine or could you tell that the alternator was knackered?
Cheers!

[CMSMJ1]

I did the checks and the alternator was goosed.. Need to ensure you get good sonnectivity and that you are measuring the plug form the genny rather than the one it plugs into ...

[1990nc30]

CMSMJ1, as i'm not working today i decided to check the alternator to see if it looked anything like your old one. I was able to get the cover off, but when i tried undoing the rotor bolt (i had to put it in gear and get my dad to put the back brake on, as the haynes says to do) the back wheel just kept turning as did the rotor. I was going to jam the back wheel with something but i couldn't find anything i could use to do the job and undo the bolt at the same time (i was on my own at this point) so i decided to put the cover back on and leave it untill later, after putting the fairings back on i went for a blast, i had the lights off to start with then i switched them on to see if it would run or not and it ran sweet all the way through the revs!? Maybe it's sorted itself out? I wont get my hopes up though as it used to run sweet with the lights on occasionly then the next day i'm out on it, it would be crap again. I think i'll get my mate to give me a hand later and have a second attempt at checking the alternator.
Cheers!