1961 CB72 Project

[G-Man]

Sara

They were used on the 1960 Dream and I believe that they act as a flywheel to absorb the irregular torque loading that the camshaft puts in to the cam chain and tensioner mechanism. I think that Honda were just being prudent.

Judging by the engines I have dismantled the cam chain does lash around somewhat so this may have been a good idea that was later deemed too expensive, or an unnecessary piece of over-engineering.

One engine I picked up showed that the chain had "sawed through" the front oil gallery.....

Oilway 4 by graham.curtis, on Flickr


It will be interesting to see how it runs / performs when back together.


The over-engineering is obvious to see on the unit as it even had a little spring plunger thing that drops into the splines on the nut as you tighten it. You cannot just spin it on you have to physically overcome the spring plunger with every spline that passes it.

[sarals]

That makes sense, Graham, thanks!

The bikes are over engineered, aren't they? They're built like tanks, but with some "trip wires" here and there to keep them running TOO long! I'm thinking bronze bushings and such.

[G-Man]

Sara

It never ceases to surprise me how much effort it takes to make something simple. Yes these bikes were 'over engineered' and that made them expensive to make. An engine with four separate chains and a myriad of roller bearings inside would make even the Brits wince.....

Your 'new' Hawk GT is a testament to the engineering knowledge that Honda has built up over the years every part in that bike will be made with less material, less machining, less complication. And it's run happily for 89,000 miles! You can see from the design changes in the '60s that Honda were learning fast and eliminating complication.

As Alfred Scott ( inventor of the Scott two stroke water-cooled twin ) said.

"Once your design is complete - you must add lightness and simplicate".......

http://en.wikipedia.org/wiki/Alfred_Angas_Scott

This was the ultimate incarnation of the Scott. Built less than 5 miles from my home but still adhered to Mr Scott's principles...

http://en.wikipedia.org/wiki/Silk_Engin ... _Silk_700S

The trouble is that people don't buy beautifully engineered, sensible motorcycles, do they.....?

G

[sarals]

Sara

It never ceases to surprise me how much effort it takes to make something simple. Yes these bikes were 'over engineered' and that made them expensive to make. An engine with four separate chains and a myriad of roller bearings inside would make even the Brits wince.....

Your 'new' Hawk GT is a testament to the engineering knowledge that Honda has built up over the years every part in that bike will be made with less material, less machining, less complication. And it's run happily for 89,000 miles! You can see from the design changes in the '60s that Honda were learning fast and eliminating complication.

As Alfred Scott ( inventor of the Scott two stroke water-cooled twin ) said.

"Once your design is complete - you must add lightness and simplicate".......

http://en.wikipedia.org/wiki/Alfred_Angas_Scott

This was the ultimate incarnation of the Scott. Built less than 5 miles from my home but still adhered to Mr Scott's principles...

http://en.wikipedia.org/wiki/Silk_Engin ... _Silk_700S

The trouble is that people don't buy beautifully engineered, sensible motorcycles, do they.....?

G

They do not! They buy plastic covered, over powered, soulless "throw away" machines that will not stand the test of time the way our old Honda's and the British classics have.

[G-Man]

Just got the engine back from the Aqua Blast Centre near Doncaster UK.

I'm pretty pleased with this. The finish has a bit more shine than straight bead blasting and, while relatively expensive, is so much better than I could do myself..

I have now got another head and barrel to replace the ones here. I will use the 64mm barrel on another project and need to get some fins welded on this head.



Engine 2.jpg by graham.curtis, on Flickr


Engine 3.jpg by graham.curtis, on Flickr


Engine 4.jpg by graham.curtis, on Flickr

[alan curtis]

thats looking good Graham, you post some good pics too, wish i could get my pics to come out like yours, mind you, what do i expect with a phone .Alan

[G-Man]

Alan

Thanks! Those pictures are taken with my iPhone. It's so good I've almost stopped using my real camera. The photos are automatically uploaded to the cloud so that I can get them on my PC without doing anything. Magic!

G