Annoying VFR800 VTEC Charging Problems

[ferrisio]

Seems like people weren't joking about the charging problems with these.

Symptom - Batt voltage 12.8v, drops to 12.1v when engine running, and doesn't move a great deal when the bike is revved

Tested - stator continuity to ground (no continuity, each phase)
stator phase-to-phase continuity (all under 1 ohm)
stator output voltage (about 18vac on idle, 50-ish at 5k rpm)
voltage drop across reg/rec terminals to battery negligible (<.1v)

I've got two reg/recs and both give exactly the same symptoms, however neither were brand new. I've diode-checked them both.

Finally, I bought a brand new decent Yuasa battery (factory recommended) thinking it could just be some dodgy battery issue - no difference.

With the fuse for the headlights removed the voltage goes up to a more respectable voltage (13+) but I've measured the current draw with the headlights in (just over 6A from memory) and it seemed respectable for a 50w bulb and the various taillights etc.

What can I try next, this is very frustrating! Current thinking is to get a MOSFET reg/rec and wire it direct to the battery completely bypassing the existing loom.
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BMW R1100R

[Tankie]

You have regulator fault, when fitting a new unit re check the earthing of this unit, I take it you have checked the plug and socket pins?
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Always learning, everyday is a school day

[ADSrox0r]

Your thinking is correct; get a decent 'fet and do a bypass.
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Current bikes: '08 VFR 800 VTEC(yo) , '07 ZZR1400 Winter hack: '95 Aprilia 650 Pegaso Currently lusting after: RC30

[ferrisio]

OK, fingers crossed - have ordered FH012AA MOSFET reg/rec from an R1 and connectors and decent cable and will bypass the existing loom entirely.

Hope this fixes it, otherwise it can only be that the stator is weak.. CBA to change that yet again. Cheers for the advice.
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BMW R1100R

[Kawasaki Jimbo]

[ferrisio]

Cheers for the link, I found a pair of new Furukawa connectors in the UK on eBay for a tenner so probably a little cheaper. Am going to solder the stator connections and run the +/- from the reg/rec direct to the battery (via 30A fuse on the +) so only one connection to be made - hope it sorts it!
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BMW R1100R

[Tankie]

Sounds like a plan , also make sure there is a good continuity from battery earth to chassis.
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Always learning, everyday is a school day

[stinkwheel]

You checked there is good continuity between the reg/rec and the battery?
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[ferrisio]

Well what are the odds.. I replaced Reg/Reg with R1 MOSFET one, and ran new wires direct to the battery, still didn't work.

Changed the stator with a cheap and nasty Chinese one I'd bought for £35 new as insurance and it works fine. I'm sure its days are numbered but it has got me out of trouble for now, I'll get the OEM one rewound I think - should be better than original then.

Didn't have a gasket, and they are a tenner for a piece of paper so made one out of a cereal box (is that still the done thing?) but it doesn't seem to be dripping any oil.

I've fitted a voltmeter so I can keep an eye on it, but I still can't work out why the stator passed all the tests (no continuity to ground, <1ohm between phases, and output voltages) fine but didn't work....?

Thanks for the advice.
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BMW R1100R

[ADSrox0r]