1961 CB72 Project

G-Man · Post by **G-Man** » Thu Aug 09, 2018 2:57 pm

Wow! Retirement really eats up your time.

I finally got around to making a drawing of the replacement tang strip I need for the CB72 seat. The early seats have this spot-welded to the pan so the plan is to grind off the remains of the old stuff and spot-weld these in place for some nice, fresh fixings.

I have a quote for laser-cutting them and they will be delivered flat. The tangs and the fixing for the welt can be bent before fixing them to the seat pan. The originals have the little welt clips spot-welded but I couldn't see the pount of that if they are laser-cut.

I'm wondering if there is any interest from forum members? I've designed them as a short, repeatable, length so that they can be fixed in different positions around the seat. Honda seemed to use some long, some short, which would put the price up. At the sort of numbers I am looking at the pieces would come out around $1.50-$2.00 each. Small numbers are prohibitive as the setup charge must be quite a big proportion.

Here is the decaying remains of one of my seats......

Any thoughts?

G

G-Man · Post by **G-Man** » Mon Nov 05, 2018 12:19 pm

Nothing much to report as I get other projects moving and my workshop reorganised. I had a little find the other day as I noticed a grubby 'diamond-pattern' early handlebar grip. It was caked in oil and dirt but it all came away in my ultrasonic cleaner.

The ugly duckling turned into a beautiful swan! Pity the grip on the twistgrip I found was completely chewed up.... :-)

G

G-Man · Post by **G-Man** » Sat Nov 10, 2018 3:55 am

Haha!

I found another twistgrip on my second visit plus some other rather nice early parts. All in need of a little fettling but nice to have. It's getting to the stage where I could make a start on a second 1961 bike but I'm going to concentrate on the 1961 CYB bike.

Rear shocks are 1962 type with steel covers and the built-in (rather than welded on) clevis.

After several sessions in the ultrasonic cleaner, I have a set of genuine original early diamond pattern handlebar grips. They are indistinguishable from the pattern ones I have but it's nice to have some originals.

I also found these NOS parts hiding in a box of other stuff. They were dirty with surface rust but everything has cleaned up really nicely. The bearing tracks on the rods and crank (RHS) bearings were free of rust marks. The cam sprocket is really nice with tight bobweight springs and an unmarked nut on the taper spline.

Feeling quite pleased with my little collection!

G

Seadog · Post by **Seadog** » Sat Nov 10, 2018 4:11 pm

Nice cache. It’s always pleasant to rediscover the forgotten bits.

border0_3 · Post by **border0_3** » Sun Nov 11, 2018 3:37 am

Hi Graham, nice work going on.

Keep on fettling.

Best regards - Richard

G-Man · Post by **G-Man** » Sun Nov 25, 2018 5:05 am

Slowly getting organised here and trying to create a bit of space.

I'm just about to take these crankcases off for aqua-blasting tomorrow. On the right is a pair of 1961 CB72 crankcases which are going to form the basis of my CYB72 race-kit bike. They are an eBay find and just 10 digits away from the 1961 frame that I got from e3Steve earlier this year.

That bike will be the subject of a new thread in the New Year. Not too sure yet wether to block that extra breather hole up or improve the design and put a threaded boss there to take an additional breather.

On the right is a pair of '63 CL72 cases. Again I picked up an entire engine (in good shape) on eBay for less than $50. The rolling chassis came my way fro about $120 a year or so ago. Could be a cheap project in the making.

Having been let down by a laser cutting person, I'm going to visit someone tomorrow who should get my new seat tang strips back on track.

G

border0_3 wrote:Hi Graham, nice work going on.

Keep on fettling.

Best regards - Richard

G-Man · Post by **G-Man** » Sat Feb 02, 2019 11:49 am

When I find a job that needs doing on one of my projects I like to find all of the similar jobs that need doing so that I can be sure I have all of the parts to restore an entire batch. It takes time in the short term but, long term, it pays off.

Somewhere in this lot is the tap (petcock) that came with my 1961 bike (not sure if it is correct) and some taps for CL72/77 and the oddball CB160.

Having checked the condition of everything, I prepared an order for David Silver. It really mounts up when you do this many but I realised that I could get ethanol-proof O-rings from my bearing supplier at around 1/10th the price of the Honda ones. That helped a little.

Here is the 23 x 2 O-ring fitted to one of the CL taps (CB160 is the same size).

The bowl/screen seal was easier to select.

Now to sort out those M3 JIS screws. Nobody seems to sell them at a sensible price so I have decided to re-furb and re-plate the ones I have and re-tap the petcock bodies to M3.5 x0.6 thread and use slightly more available m3.5 screws which I can get in stainless steel. I have bought an M3.5 tap and a pack of 100 screws just to be on the safe side.....

G