Hi all, I installed a voltage regulator on a CT1 a few weeks back and just put in a new 4020 6V headlight. Battery is new. The headlight dims and brightens with acceleration so wondering If that is normal or if I have the VR installed wrong. Yellow wire from the VR is plugged into the light blue wire in the bucket. All the instrument illumination looms are missing except one I picked up on eBay but that bulb needs replacing. Tail light and brake light doesn’t seem to dim and brighten like the headlight. Appreciate any confirmation. Would hate to blow a new $35 headlamp. 

What year CT1? 

I can only remember one blue up front and I don't remember it being terribly "light".  But my memory is sometimes not the best.

Beyond that, the other lights are running on battery which is more stable. 

The headlight will be dimmer at Idle but should be full brightness at 2,000 or maybe 3.000 rpm at the most? 

Cool, it’s a 1969. The wires could be lightenEd by exposure. I think this bike must have been exposed to Long term sunlight as every wire in the bucket is very crispy From sun damage. 

Genuine light blue in the headlight bucket (from the main harness) is for neutral light. This will have a male bullet connector, which plugs into the same colour wire with female bullet connector coming out of the tacho lights sub harness.

The slightly darker blue wire in the headlight bucket, also from the main harness, will have a double female bullet connector on the end and this takes the blue male from each of the speedo and tacho illumination lights. It is here that the voltage regulator should be spliced in (see Service Bulletin in the Tech Library).

On my 1971, 1972 and 1973 bikes, there is another blue coming from the switchgear, but this is in a plug connector with the pink horn wire.

If anyone is interested, my own procedure for connecting up the regulator is to make up a short pigtail harness, with a single male bullet connector at one end and double female at the other. I remove one of the tacho/speedo light blue males from the existing double female and replace it with the male from my pigtail. I then plug in the male that I have removed, together with the wire from the voltage regulator, into the double female on my pigtail. 

69 might have the taillight running off the engine on the same circuit as the headlight.  Depends of when it was made or if someone changed parts