CB750K1 Headlamp unit

[deedub]

Hello all, I have a period Cibie sealed beam headlamp unit fitted to my K1. Am i right in thinking that these when fitted as an upgrade just involved putting the unit into the stock inner and outer rims?
Ultimately i want to go back to original so i,m hoping to just having to buy a UK glass and reflector and slot it straight in.
Can anyone here confirm this please?
Regards Dave

[hairygit]

To be honest, if you intend to actually ride it rather than put it in a museum, I'd leave the Cibie on it, far better than stock, and a totally acceptable period modification.

[mike the bike]

Would that Cibie unit fit a 400four, because my headlamp is piss poor.  It's like riding with a candle in a jam jar.

[Chris400F]

Methinks not, the 400 headlamp is only 6" whereas I think the 750 is 7".
The Cibie unit you could get for the 400 was slightly smaller than the standard unit and came with an adaptor ring which fitted between the headlamp rim and the light unit as well as different fitting clips. The adaptor ring may have been different according to what bike you were fitting the lamp to, I don't know. I have one on my 400. They come up on eBay occasionally, which is where I picked up mine. Certainly a period modification and a great improvement on stock although I don't think it is a Z beam.

[K2-K6]

I think the original cibie conversion for the 400 was a "bi Oscar" in terms of what cibie called them
them.
Oscar refers to that size of light shell with the bi being a two filament bulb. You should be able to get a new one from some of the car rally supply guys.

As Chris says the 400 headlight shell needs an adapter ring to make them fit.

The same sized light units 160mm are used in things like triumph stag, dolomite sprint and BMW 3 series as well, these all using H4 bulbs but the bosch units fitted to BMW maybe too deep to fit your shell.

[Chris400F]

As requested, a picture of the glass and a few more for good measure. Maybe someone can now confirm whether it is a Z Beam or not.
The lamp unit is 5 3/4". Units of this size are still available, but these have convex glass whereas the units sold for bikes had concave glass.
The adaptor ring is stepped so it wouldn't be as simple as making a template and cutting a ring to suit, although that may work.
The final pic shows the retaining clips - top is one that came with the Cibie unit, bottom is an original.

[AshimotoK0]

I had one of those in the last pic on a 400/4 and it was absolutely superb compared with standard. Would fit one to any one of my bikes without hesitation and the one part I would fit and say b*llocks originality apart from tyres.

[Chris400F]

Pretty sure this is an original unit, it looks as I remember them from back then with the light unit nearly filling the rim.
I can't be sure but 5.25" doesn't seem an obvious size of lamp to use for this type of conversion. It would need a wider adaptor ring and would have to have an offset locating tab in order to line up with the locating tabs on the headlamp rim.
That seems to be the difference between motorcycle and car units - the motorcycle ones have a locating tab fitted at the top instead of in various places around the unit.
You can still buy 5 3/4" car headlamp units but a suitable adaptor ring would need to be constructed if you were to try to fit one to improve light output, and of course you would then be even less original (although you would be able to see where you were going).
Another alternative could be that this guy (http://www.norbsa02.freeuk.com/goffybulbs.htm) has halogen bulbs in 35/35W, 50/50W and 60/55W ratings to replace the bulb in the standard headlamp (Bosch BA20d Bayonet Cap type). Might be a way of improving the light output.

[mike the bike]

I'm thinking the superdream headlamp will fit a 400four and that has an H4, 55/60W bulb.  M & P have them for £31.  I'll get one and post my findings.

[Chris400F]

I thought the Superdream had a 7" headlamp but M&P list both 6" and 7" versions for that bike.
From the price you are obviously looking at the 6" one.
Keep us posted! Especially with regard to fitting (thinking particularly the mounting hardware).

[mike the bike]

The headlamp arrived a few days ago and I've just got around to fitting it.  Firstly,  it's not exactly like the superdream ones;  the rim is 400F profile rather than 400N profile.  Having said that, the fixing tabs where the M5 screws fit into didn't line up with the holes in my original shell.  The tabs were too short in other words so I used the original rim.
The green, white and blue leads came without bullet connectors so I fitted new ones.  Not surprising really because 400N connectors are different anyway.
The side light 💡 is a wedge bulb, yellow so I put a white one in.

In summary,  it took a bit of fettling to get it to fit but I've now got an authentic looking 55/60W H4 headlamp and I consider it well worth the time and effort.
I'm now going to sell the original headlamp and the superdream shell and rim on ebay