Hi all,

I've searched through several threads and forums and decided to post as I'm not quite sure what i can do.

Issue : My missus' rvf400 was working fine but one morning, the bike won't start. We changed the battery(I had a few spares) and it was all working great until one day the low beam(bulbs are ok though, filaments intact) stopped working(high beam works). It has the standard 35w bulbs fitted and not the h4's so not likely a reason to fry the lhs light switch. However, after riding for a few days, the battery will be drained completely where the bike won't start if stalled.

I have 3 batteries all holding 12.8v off the bike and with the bike running at idle as follows

idle with low beam(no lights though) : 12.8V
idle with high beam(lights on) : 12.4-12.6V
Rev at 5k with high beam : 13.5-14.

From the info above, I can only assume that the high beam(since low beam not working) is drawing too much current, and since my missus' commute is on the short side(6miles in heavy traffic), it drains the battery to a point if she stalls, it wont't start. Does it look like the regulator is on the way out etc?

Is the above true? Or should there be no impact when running at high or low beam?

2nd of all, since the bulbs are fine, I can only presume its the light switch. Can i take the switch gear off the bike-(discconenct from loom) and take it apart in the comfort of the house? From a quick check yesterday, it seems that the lhs loom connects to the main loom and unable to disconnect. Please correct if wrong.

Last of all, what do i need to do with the switch gear to get it working again?

I think those figures are fine. With the lights on on an RVF, the voltage at the battery at idle usually barely exceeds the voltage with the ignition off, if at all especially if the system hasn't had the reg/rec direct wired to the battery. Obviously high beam will drop it. 13.5-14 at 5K with high beam on is perfectly adequate to recharge the battery.

If the low beam doesn't work it usually means the switch is knackered, however the most common cause of that is using 60/55 H4s. It's still not impossible that the switch is shot, so it would be a good idea to test it with a multimeter. The switchgear is connected to the loom under the fuel tank where the front fits under the frame, so it's a pain in the bum to get at, but yes, you can take it off.

If the bike is being used with high beam on and is spending ages in traffic idling, it is possible that at 12.4-12.6V the battery is being slowly discharged, although I was informed on another thread that you should be able to leave the bike with the ignition on for half an hour before the lights discharged the battery to the point where the bike won't start if the battery is 100% healthy and 100% charged when you start. I guess there might possibly be a short somewhere in the low beam circuit.

Ultimately, if the high/low switch is knackered, then it needs replacing. They come up on eBay sometimes, if not, you can still get them from Honda. And they're a mind boggling £135!

NC35 is wired to pass the low beam headlight power through START button as part of the "lights always ON except when engine starting" function. Suggest you check the START button to make sure power is available at the Blue/White wire before the START button is pressed and also after it is released.

Given the short distances traveled and the design of the OEM charging system, I doubt the battery is getting an adequate charge. Below are the battery voltages I measure now that I have directly wired the rect/reg to the battery, much better for keeping the battery charged during short runs especially with NC35 lights always ON.

Idle:

No lights 14.0 volts
Low beam 13.3 volts ( expect 13.0 volts with 55/60 watt headlight)
High Beam 12.7 volts

RPM to achieve 14.6 volts:

No lights 2000
Low Beam 2500 (expect 3000 with 55/60 watt headlights)
High beam 3500

Thanks for the replies guys.

I think i'll check out the following in succession.

blue/white wire into lhs(this is low beam right?) and i test this by one end of multi to the wire, and one to the frame?

and then blue/white wire into the rhs to see if power is going into the switch for the lights?

The question is no voltage present in the blue/white going into the rhs, what do i do nxt?

Thanks

On LHS there are two connectors one with three wires and second with nine wires. Do not unplug either connector.

In three wire connector there is a blue/white wire that should have 12 volt dc to chassis with ignition ON and the START button NOT pressed.

If 12 volts missing then START button switch or blue/white wire is faulty.

If 12 volts is present on blue/white wire then go to nine (9) pin connector and check for 12 volts on white wire.

No 12 volts then light switch is faulty.