1961 CB72 Project

[G-Man]

The great thing when you're not in a hurry is that you can pick up any part and take a look to see what, if anything, needs doing. The carbs on this bike looked decent enough but a little dirty. I completely stripped them down and then I realised that I had one correct "round" bowl instrument and one later "square" bowl version. I looked on eBay for days and found nothing and then more out of desperation than anything else, started rummaging through my spares box.

There it was, the matching half of my set. Another PW22HOV carb. Rather than the marking on the flange, these have their model number on the side of the body near the top.

All three bodies went in the ultrasonic cleaning bath after all fixings were removed. After a thorough cleaning each had a quick wash in phosphoric acid to bring back that nice fresh look. I can never get that "good as new" look but this helps.

Both of the flanges on my new "set" were bowed from over-tightening so I tried flattening them with wet or dry paper on a sheet of glass. after a few minutes of this I found I was making them worse, so they were carefully clamped in the lathe for a light skim with the sharpest of tools.

After a session on the wet-or-dry paper you can see that contact is patchy. The shiny parts are the high spots and the gray are the low spots.

carb on wet-or-dry by graham.curtis, on Flickr

Light cuts on the lathe take off the highs until the contact is nice and uniform


carb in lathe by graham.curtis, on Flickr


Here you can see nice even contact


carb -trued.jpg by graham.curtis, on Flickr


G

[Waveblaster]

Graham

Lucky to have a lathe, a definite nice to have!

I have a couple of 250 heads with 10mm plug orifice could possibly spare one, I am chasing a 305 180 crank if you have a spare and feel like a swap in some way

Greg

[G-Man]

Greg

Sounds like we might have some kind of deal in the making. The postal service may be the big winner here. I'll have a look to see what I have spare. Are these heads CB (twin carb) ?

G

[Waveblaster]

Yes twin port, to suite 250cc , so doesn't have the squish band as you call it , just the hemisphere skull cap.

Not sure if there are variations based on year you may wish to look for

[G-Man]

Greg

10mm plugs says all I need to know....

Sent you a PM

G

[alan curtis]

hi graham, in the pic with the fork bridge, thats a 62 one, (with holes in the side) the one on the bike looks right no holes..or is it a test ... alan

quote="G-Man"]I have managed to collect quite a few of the parts needed to get this bike back to original.

Alan Curtis came up with a really nice SLS brake plate and speedo drive, while a set of the big front forks and front hub came from Mister Monkeyclaw on eBay. The early speedo drive is unusual and drives an external tang via two slots in the hub.

SLS front brake by graham.curtis, on Flickr


Bill Silver came up with a NOS rear light assembly that will bolt straight on to my existing bracket. Alan also provided a wiring channel to convert the later type rest fender to an early type.

The early, larger diameter front fork needs all different shrouds. NOS lower shrouds and lower triple clamp came from CMS and the headlamp ears came from Nick at Ohio Cycle, courtesy of Conbs.


Front triple clamp by graham.curtis, on Flickr


Alan spotted these aluminium rear shock covers on a stand at the Stafford Classic bike show when I was in the USA. Thanks Alan! I had actually bought some material to make my own and might do that as a project later.

Shock Covers.jpg by graham.curtis, on Flickr[/quote]

[G-Man]

Alan

You're right! The one from the bike is in a box somewhere covered in 40 years of dirt. That one was just sitting in a box next to the other parts that I have been collecting. I would have worked it out eventually..... maybe :-)

Thanks

G