VFR400 nc30 regulator rectifier problem??

[loufred]

Hi everyone I am sorry if this has been done a million times but I am confused with what's wrong with the bike I have just got off a friend.
I know before I got the bike my friend had issues with the bike blowing fuses and bulbs so he got a new battery and a new larger regulator rectifier from ebay which after fitting he thought he had fixed the problem, he only used the bike a bit and then sold it to me.
The problems I am having is that I have fully charged the battery twice now with the bike not charging up the battery itself, last night I had to jump start the bike but if I turned the lights on or even press the brake light on the bike would die. I did have a issue ones where the bike wouldn't start after I put some petrol in but started the next day.
I have now fully charged the battery and the bike seams fine, but I need a bike which I can safely use as my commuter bike.
Any help or suggestions would be very much appreciated.
Regards

[skinnydog0_0]

Sounds like your genny may be fecked. Have a word with geoff33 i am sure he will have a spare for sale.

[Man_Named_Dave]

You may well need a new genny, reg/rec and battery.

[loufred]

well it has just had a new reg and battery so i guess it must be the generator, is this a easy job to replace and would anyone have a working one for sale?

[magg]

Before you start the task of replacing the alternator why not try a couple of simple checks. Take a multimeter and check that resistance and output voltage from the alternator by unplugging the connector at the rect/reg and connecting the multimeter between the three yellow wires, a-b, b-c and c-a. Resistance should be about 1 ohm. Also measure resistance between any of the yellow leads and the bike frame. Resistance should be infinite.

If you do not get a satisfactory resistance reading between the three yellow leads, then I would check the alternator connector located under the carbs between the V. This connect, along with others in the charging system, has a habit of failing.

If resistance readings are ok, then measure the AC voltage between the yellow leads, should be 50 volts or better at 50000 rpm.

[V4beermonster]

had similar problem with cheap jap reg/rect was charging with lights off but not when lights on just check this

[loufred]

I just checked the bat and got like 12.95 volts from the bat right after coming off the charger, when i turned on the bike and revved it the current volts didn't go up but went down a little, I then unplugged the rectifier and tried to check the readings from 3 yellow cables, i didn't get no reading from any of them. so would that mean that the alternator is fudged?

[magg]

There is an alternator wiring connector located in the V under the carbs that can fail, plastic melts and wire break-off. I would check that before replacing the alternator.

[loufred]

How do I get to this, do I have to take off the petrol tank and is this a easy job?

[magg]

You need to remove the lower fairing on the left or right side and follow the wiring as it comes from the alternator. At a point about midway across the top of the crankcase you will meet a connector.