A quick starting question......

[jamestnewsonr65]

If the headlight bulb is a bit flaky, would this prevent the bike from firing up?

Bit of history: I replaced my h4 bulb with an led bulb and all has been well for over a year, but tried to start the bike today and no joy. To ensure the led works correctly some of the wires in the headlight connector had to be changed around.

At the moment the bike seems to start under the power of the starter motor, but as soon as you blip the throttle to start or release the starter it stops.

I have had the same issue before and replaced the bulb with a standard h4 and it started, so was just wondering if there is something up with using a configuration with an led bulb which may prevent the bike from firing.

I've ordered another standard Philips h4 bulb and will return the headlight to stock configuration re the wiring to see if it solves it.

Any thoughts or advice much appreciated.
Also this might be a simple wiring issue but I am not too good with the electrics unless following a guide.

Thanks in advance

[montmil]

... To ensure the led works correctly some of the wires in the headlight connector had to be changed around.

When a new problem pops up, always return to the last item you messed with. I would suspect that your "changing around" some wires is the problem. Put them back as you found them, install the correct headlight bulb and the bike will start and run as normal.

Check your bike's wiring diagram. If it's a Euro-spec bike, it may be wired slightly different from North American issues.
     Most, if not all States require motorcycles to have headlights on at all times. My Airheads are wired such that when the ignition is switched on, the headlight is on. When the 'start' button is pushed, the headlight goes off so that all battery power goes to the starter. Engine fires and the headlight is back on.

Report your findings after returning your bike to original baseline.

[mrclubike]

It sounds to me like you have caused a short to earth and that is causing the voltage to drop in the ignition circuit.
It could be the LED replacement bulb or the moving of the wires in the plug
Because their are no fuses in the headlight circuit you could be burning up your headlight switch, relay and related wiring.
I would be very careful  doing something like that with this system  
That is why I have added fuses to everything.
I have no idea what the electrical engineers at BMW were thinking when they designed this.
I tried putting LED tail light bulbs in my Grand Cherokee and as soon as I would hit the brakes the first time after installing them they would short out and cause feed back thru the headlight circuit. I tried 2  sets of them and they just would not work so I went back to regular bulbs.  

[Barry]

There is nothing inherent in an LED bulb that would cause the problem so if it's an electrical issue then it has to be a wiring fault.

You wouldn't start a Euro spec bike with the headlight on and as Monte said US spec bikes have a headlight relay that switches off the headlight while starting.

The obvious first test is to monitor the voltage at the ignition coil while starting and see what happens.  Assuming it's a Euro spec bike with a single dual output ignition coil, connect the voltmeter between Terminal 15 on the coil and earth. You should see approx. 12.5 volt with ignition on which will then drop a couple of volts while cranking. If the voltage disappears when the starter is released then you know that it's an electrical problem. If it doesn't disappear then the failure to run is due to something else.

[jamestnewsonr65]

Thanks for the info. I will do a bit of exploration. All has been working well for over a year in the current set up, I have noticed the bulb behaving strangely or it may be the switch, but will return to stock wiring and see what happens.

[jamestnewsonr65]

So I got home tonight and the new bulb was here so I thought I would put it in and switch the wiring back. Headlight works as it should, but I didn't start the bike as I don't want to wake the neighbours. I did notice though that the headlight switch may be the issue or at least the circuit. When I switch the push to pass the light goes out but with a wiggle it works. The switch to full beam doesn't work at all.

Would this indicate a wiring fault or just a fault in the switch?

[Bob_Roller]

Most likely a faulty switch .

I'm on my second replacement switch .

Some members here have disassembled the switch and have fixed problems, but it's not very ' user friendly ', springs and small parts, no individual parts are available for the switch .

[mrclubike]

 Does sound like a faulty switch now but the LED bulb could have shorted out and burnt up your light switch.
On my bike I have a relay that takes the load off of the light switch and if the light switch does fail open I will still have low beam.
Wish I had a schematic of a EURO spec R65.
Any one have a link to one on-line.  

[Barry]

I have a PDF of the early Euro model if that's any good.

[jamestnewsonr65]

Think I will take the switch off and see if I can see anything which is fixable/needs cleaning or burnt out. I was looking at a replacement but at £50 or so for a second hand one I might see if I can fix the existing one first.

[mrclubike]

If I remember correctly you have to remove yellow dip switch lever first to get it apart.
You just pop it straight out to remove it.

 Barry can you post the schematic to the thread  :

[Barry]

Here it is the best quality wiring diagram to be found anywhere and a translation of the legend I produced to go with it. You can zoom in too this diagram as far as you like to see the detail and the quality is maintained

[BPT]

Barry-that is a great diagram.  Is it safe to say that it is Euro-spec?  If so, anyone know how much difference there is between Euro & NA?

[jamestnewsonr65]

Thanks for the diagram Barry. I've ordered a 2nd hand switch to see what happens with that one. If the problem persists then I'll look into it further.

[Bob_Roller]

The NA version, will have different ignition switch wiring, the Euro switch has one more position that the NA bikes .

The NA headlight circuit is different due to the head light relay that cuts out the headlight during starter operation .

If you have a second generation twin shock R65, build date of 09/80 or later, those bikes have electronic ignition, this wiring diagram shows contact breaker point type ignition .

The front brake light circuit has a pressure activated switch looks like an oil pressure switch on the first generation R65, the second generation has a switch activated by the front brake lever .