VFR800 Regulator Rectifier Fail

andrew Maintenance, VFR Leave a Comment

I’ve read about it, I’ve seen it many times on numerous internet forums, but I never thought it would happen to me. When I bought my bike, I checked to see whether the original had been replaced, and saw the words Tourmax on the top of the unit, and assumed this was an aftermarket replacement. All good. Then I started to notice the battery going flat.

Initially I assumed his was down to the cold weather, and the fact that I was using my heated gear, which draws from the battery. So I stopped using the heated gear, the battery still would up flat. One time leaving work I had to bump start the bike, and othe other time leaving Gloucester Services after stopping for some emergency Mont d’Or (they do have some rather excellent cheeses in Gloucester services).

Out came the Haynes Manual, electrics section, charging, and a level 1 diagnostic was run. It goes a little like this, check the battery is charging properly which means over 14v at 5000rpm. Mine was reading 13.6V. If not over 14v then check the wiring to the R/R.

Next, the alternator feed was checked for resistance: 0.6 Ohms between each of the three coils, and no continuity to earth, that’s fine. Next the other connector is checked (on the loom side not the R/R), all good there. The book says check the R/R by swapping it out. Great.

£101 later and David Silver spares ship out an OEM unit which I’m installing tonight. It looks remarkably similar to the outgoing one, albeit with an aluminium plate to which it is mounted, presumably as some kind of heat sink. I’ll let you know how it goes. When I plug the old connectors back in, I’ll be dosing them in ACF-50 just for good measure and to keep those connectors from seizing up in the future. This is one thing I don’t want to be replacing. Bummer.

Just swapped out the R/R, checked the battery, it’s reading 14.4v, so it was the regulator / rectifier. We’re back in business. How does it feel? Like my bike has had a heart transplant. The bike fires up immediately whereas before it would turn over and over before finally firing into life. It feels more sprightly too. I obviously hadn’t noticed the gradual demise of the charging system, and just thought the bike had a worn alternator, it turns out it was the regulator. Who knew? Most VFR owners, it seems.