XR200 headlight

[lazza]

Hi all, i'm new to the board so sorry in advance if this question has been asked before.
I have a 82 XR200RC trail bike, with a dull headlight. It's the model that doesn't have a battery or regulator/rectifier it's purely one wire from the lighting coil to the headlight. It has approx 7vAC and doesn't get much higher than 8v when up around 3 - 4000rpm. The lighting coil has the correct resistance reading to what the workshop manual says so i was wondering if there is some "item" other than a battery that i can add to the circuit to allow a constant 12v supply to the 12v 35/35w bulb it currently has
thanks

[merv]

Now tell me if I'm wrong but weren't they meant to be a 6 volt system so stick a 6 volt bulb in it which at 7 volts will be sweet and bright.

[lazza]

well the workshop manual says they are 12volt so i'd be fairly sure it has the right bulb in it

[FROSTY:Me]

Dude i'm no XR200 expert but they have been around a long time. My memory says its a 6v system in the xr200.
If it is 6'v lectrics then easy --use a 6v bulb.
If it is genuinely a 12v system then you need to be sorting out your charge system so its pumping out the correct voltage

[lazza]

ok thanks i'll go double check things

[What?]

Frosty's memory is right - 6 volts it is.

[ynot slow]

Had a 1980 model with same problem,put a 6v dry cell in and good lights,one guy reccomended a lower wattage bulb which would give brighter light.battery in rear bumbag compartment behind seat,kepy dry inside plastic bag and took up no room,also meant idiots behind would see the piss ass tail light too,afterall it's an off road type bike with lights,well they were marketed as such then.

[merv]

So we're all saying 6 volts. The C is about a 1982 model, I had a D which was 83 - fantastic bike and I didn't have any light hassles and don't think I ever had to replace a bulb for that matter all the time I had it. Sold mine in top nick complete with manual so I don't have any reference material for it to help you any further.

[Coldrider]

Surely it has a rectifier to convert AC to DC, should have a capacitor across the DC output to smooth it out, this also increases the voltage.
The rectifier might be within the coil, an alternators voltage will be sky high with no load attached, the rectifier itself being a load.
A rectifier usually has four diodes in a bridge configuration within to convert AC to DC, one diode may be open circuited (blown) causing it to half wave, thus limiting the output current so the lamp is dim, the voltage would then drop as the output load increases.
I restored the electrics on an old Yamy TT500 years ago, I connected a 20A bridge rectifer (from a electrical supplier, RS type) to the alternator output, put a capacitor (1,000 mf) I think, put an inline fuse, and that ran the lights.
The rectifier is likely to be around the coil and be a little black plastic unit.