VFR 400 NC30 1989 - Reving Problems - HELP?

[Problems]

Hi all,
Over the last few weeks, the temperature has dropped and my old battery in my bike has been having a few problems starting my bike. In the end I replaces the battery with a new one (YTX7A-BS) (A cheap one off ebay) but found that it had a different battery in the bike, the larger (YTX9-BS). (I only put this in as a new battery is only thing that has been changed on the bike).

As I took the bike out, the bike reved up all the was though first to fifth with no problems, reving all the way up though the gears . In the last gear (sixth), this is were i found a problem, the bike wouldnt rev past 7000 and even then it sounded as if it was hard work just trying to do that.

Anyone have any ideas?

Thanks.

[Problems]

Hi all,

Used a multimeter today to check the VFR Charging systems, using the simple VFR Charging systems guide that can be found on this website ( the file that can be found in the Document Library, http://www.400greybike.com/docs.htm ).

I started by allowed the bike to warm up to running temps before i started and then checked the output on the battery
when reving the engine at 5,500rpm, the output coming out at around 12.5.

This would indicate maybe one set of coils in the alternator is burn out?

I also disconnected the connector that when into the reg/rec unit and found that this connector was burnt/ melted.

Guessing i should replaces the connector right?

Does this this also mean the reg/rec unit may need replacing?

Any help would be great,
Thanks,
Andrew.

[CMSMJ1]

Hello Andrew

Yes - exactly as you say. The reg rec probably a bit knackered and as you noted the plugs for the reg rec is fried then it is pretty obvious. Check the plug by your right knee too - comes through the vee and is also a white 3 pin and prone to melt.

Welcome to the site :)

[Problems]

Hi CMSMJ1,

Thanks for the confirmation that the reg/rec and the connector should probably be replaced, ill order them now.

As you said to iv check the 3 pin (yellow wires) connector and found that it was fine ( Old looking but not melted or burnt)

but something i am finding hard to understand, is finding out weather the stator from the generator/ alternator has been damaged?

Or should i replace the reg/rec and the connector first and then check to see if the reg/rec and the connector is ok?

Thanks again,

Andrew.

[CMSMJ1]

checking the stator is easy

set the meter to AC and then test each of the yellow wires in the plug by the vee in pairs AB, AC, BC - you should get up to 50vAC in each pair.

if one of the phases is knackered you'll not get your 50v - it fluctuates with revs so get someone to rev it.

I'd assume the reg rec is toast - they take a beating once that plug starts to melt. Test the stator - it is probably knackered.

[Problems]

Ok, well i'm ordering the reg/rec now so its getting a new one even if it does need it.

Ill check the stator tomorrow night and ill say what happened, but thanks for the help!

Really for a beginner, this place makes it a lot easier to get your head round.

Just saying that the stator is damaged, any ideas were the best place to pick one up is?

Thanks again,

Andrew.

[Problems]

Hi,

I tested the yellow wires in the three pairs.

I tested them ( with the setting at V~ 200, meaning 200v for range with the resolution being 100mV)

and only got around 6vAC on all the pairs, held at 1500 revs with warmish engine.

I tested them again (with the setting at v~ 600, meaning 600v for range with the resolution being 1V)

and only got around 5 on all of the pairs, held at 1500 revs with warmish engine.

So does it mean the stator is damaged and needs replacing?

Or is the stator (therefor my alternator/ generation) ok?

Thanks,

Andrew.

[CMSMJ1]

you want to get some revs - 5k revs should get you approx 50v AC on each pair. Maybe slightly less.

if that is the case, then you are proving that the stator is fit for business.

If you did need one, then get one from someone second hand - they can be had cheap enough.

Off the top of my head there is also a resistance test you do on the stator to make sure none of the wiring has broken too.



And yes- this place is the law. I had the same issues as you - going to be about 7 or 8 years ago.. if you are lucky I'll post my fucked stator picture :)

[Problems]

Got you, Ok well Ill check the stator again tomorrow night doing both the ac and resistance checks and ill say what

happened and again thanks for the help. Oh god, how bad did your stator get?

Thanks,

Andrew.

[Problems]

Hi all,

So tested both the AC and resistance for the generator/ alternator,

Testing the Ac with the multimeter (with the setting at v~ 600, meaning 600v for range with the resolution being 1V)

reving the bike to around 5000, i got about 20Vac on all the pairs , instead of the 50.

Testing the resistance (with the setting at 200, meaning 200 for range with the resolution being 0.1m)

letting the bike tick over, i got around 18 to 20 on all the pairs, instead of the 0.1 - 1.

Guessing this means the stator is fucked and i will be buying a new one then.

Thanks,

Andrew.