Noticed that the headlight on my '85 RT is too low, so began the adjustment proceedure. According to the manual; Roll the bike up to a wall and mark the height of the headlight. Then, back the bike off 15 meters (yards) and adjust the light to hit the same spot.

Well, my light comes up about a foot too low so, got out the trusty wrench and began turning the adjuster (located down on the lower right side of the faring). After about 20-30 turns, no effect.

My suspicions are the faring was replaced sometime in the last 25 years before I bought it. Perhaps the adjustment assembly wasn't put back together correctly, or perhaps a dozen other reasons.

Any thoughts from people who have successfully adjusted their headlamps?

Not sure but I will be watching this one as I must also do the adjustment. I have taken an electric adjuster out of a car headlamp and looking to fit it to get over the problem of the beam also being too low. The manual one is fiddly and I suspect not installed correctly. My fairing was definitely off the bike at some point.

Straight from the riders manual

there are actually 2 adjusters ...(speaking for left hand side of road users )
looking from the rear (drivers perspective )

there is one down the left hand side near the diagonal apex at the top ....this gives left to right correction

there is one with the clip and bolt on the right apex (bottom ) almost straight across the back of the headlight assembly ...this gives up down adjustment    the (white ) clip part is actually a lever assembly which is supposed to be a "quick adjuster" compensator for 2 up riding ...
so it has an up and a down position ....which is a cam like action  and basically holds the nut for adjustment at either of 2 presets
 there are limitations on the adjustment though ,
both these adjusters are a long thread with spring loading

perhaps one of the issues could be that the rubber diaphragm which seals off the back of the globe mounting assembly to housing could have hardened ? this could restrict the amount of movement of the reflector assembly
or someone has been inside before and made some adjustments ?


here is a pic of the inside of the housing without all the hardware in place  so you can see the relative locations



you can see a mounting pivot point in the top left (from the front ) where everything mooves from and is the only "solid point "


here the white clip is in the up position ...single up riding



here the white clip is in the lowered mode  for 2 up riding   it would be hard to wind the position adjustor (the nut in the centre ) whilst in this position

so if you want more height make sure the clip is in the "towards the top of the housing position"  before making adjustments
to raise the beam vertically you would need to undo the nut ..(which is a long 5mm threaded rod into a plastic clip ) so that's anticlockwise ...if you were to tighten = lower the height ...(wind clockwise too much), you might just strip the plastic retainer  or wind it up onto the shoulder of the bolt  so it has no action on the unthreaded rod section of the bolt in the plastic ?

hope that helps aj

Hi AJ,
You might find some useful pointers in this post if you need to take the headlamp unit apart.

https://www.k100-forum.com/t4520-the-rs-rt-headlight-unit

Cheers,
Paul.

great "how to"      paul

Thanks for the information. It's going to be winter before I can get inside and see what the problem is. We'll come back to this thread if I find something interesting.

OK, I have the answer. Note, I've been using the repair manual (dated 4.1988) downloaded from this site (not the one posted here by RickG). To paraphrase from Chapter 63, p8.87, under the heading K75C, K 100 headlight adjusting, regarding the knurled screw and associated picture:

Turn anticlockwise = beam throw shorter
Turn clockwise = beam throw longer

This is wrong! See my previous post where I had cranked the screw 20-30 times without getting it to come up to the mark.

Thinking about this more, a normally threaded screw turned clockwise would shorten its  length, pulling in the bottom of the chassis in and causing the beam to travel downward. (I suppose if the screw was at the top of the chassis the action would be reverse, but it's not.)

Then one night I was riding along one of twisty unlighted streets along the Sugar River here in town where I'd ridden a hundred times before, this time noticing my headlight was  much lower that ever before!

So, when I got home I cranked the nut counter-clockwise 20-30 turns, and the next chance I got (last night) I made the final adjustment. 

I thought I was following the instructions properly, and indeed I was. Never occurred to me that the manual would be wrong on something so basic as this.

I have done quite a few manuals and other publications by scanning the original then making a new page that is clean and has good print and it truely amazing just how many mistakes there are.
I think the worst one I have done was the factory manual for the Z 1300 Kawasaki.
The BMW ones are fairly good but Haynes and Clymer have some classic bloopers.
I am currently doing the Haynes for the K100 up to 1988 but it sure takes time.