HOW 2: VFR800FI Heart Bypass Surgery – Sorting Out Poor Charging Issues

andrew VFR Leave a Comment

Does your VFR battery struggle to hold its charge. Does the engine feel rough at high rpm ‘s? Before you go out and replace your battery and regulator/rectifier, let me tell you about a fix which has transformed my bike for £5.69.

The bike has been poorly for at least the last six months. I first noticed when it stalled and couldn’t be restarted at the end of a commute home. New battery? Perhaps. Or the charging system. I’d already replaced one regulator/rectifier. Surely I don’t need another already?

I flicked on the trickle charger every time I was at home and parked up in the garage to keep the battery topped up. Three weeks ago, I eventually decided to investigate the problem, so out came the maintenance book.

I checked the alternator coils, all were under 1 Ohm resistance, which means they’re fine, I checked continuity, earthing and battery current leakage, all fine. I did the standard test with engine up to temperature and running, with the lights on full beam to measure the voltage across the battery at 5,000rpm. It was 13.2V. It should read between 14 and 14.8V

The book says that a new regulator rectifier is required. £100 later I had a new one. Not ideal but not the end of the world. Except it made no difference at all to the charge reading. I was still getting 13.2V at 5,000rpm. There’s something else amiss.

I got online and found this post on a VFR forum in 2007. The poster, Zam70, has experience of automotive electrics and expressed a need to bolster the charging systems of both cars and bikes with additional wiring, as the original wiring is rarely generous enough.

I got a piece of wire, stripped the insulation off both ends, and with the engine at 5,000rpm and with full beam lights, hooked it up between the battery negative and the frame. No change. I then hooked it up between the regulator negative (green lead) and battery, no change. Next I hooked it up between the regulator positive (red / white) and battery positive. BINGO! 14.8V

So it’s down to the dodgy wiring. The alternator was charging, the regulator was regulating but the battery wasn’t getting any of the juice. Now to administer a more permanent solution. Off to Halfords G and I went, in order to buy a fused lead:

This I assumed would be long enough to use as is. It turned out to be the case. The regulator connector is very close to the battery positive terminal. I already had a 30Amp mini blade fuse to put in it. The standard system charging wire has a 30A fuse, so I just replicated this with my additional wire. I also bought some 60/40 roisin core solder and silicone grease online.

Out came the blowtorch and I soldered a ring terminal on the end of the wire, and fitted a shrink wrap tube, the other end I fed into the terminal block adjacent to the red/white wire and sealed the end with silicone grease and taped and cable tied the cable in place.

Did it work? In a word, yes. One return trip to Bristol down, and I have checked my charging voltage at the end of both legs of the journey. 14.8V at 5,000rpm with full beam lights.

It’s a revelation. The bike feels much more sprightly. It feels like a new machine. Sometimes is is so responsive that I wonder whether it might be starting to behave erratically; obviously the engine and throttle have been pretty lifeless up to now.

I also note that the engine is far smoother at higher RPM. I had wondered whether the roughness I had noticed before was just down to the bike being old, it just turned out the engine was putting strain on the battery and it wasn’t being recharged; it had a weak heart.

But now I’ve performed VFR heart bypass surgery, all the essentials are flowing well again.

If you have a VFR and notice any of these symptoms:

  1. Battery not holding its charge
  2. Rough engine, especially at high RPM
  3. Indicator / light use causes a dimming of other lights (clocks)

first try fitting a new charging line. If it saves you the price of a new battery and regulator/rectifier, that’s £160 saved. Your bike will feel much better. You will feel much better.

Oh, and while you have the fairings off, clean your connectors with contact cleaner, spray with ACF-50 and seal ends with silicone grease.

Leave a comment below, and share with your VFR Riding mates, or anyone with a charging issue.

Happy riding