Friday, January 07, 2011


Alain deCadenet and Malcolm Barber discuss a '67 Velocette Thruxton, which sold for $25,000, not including buyer's premium.  Total sales for the day were $2.5Million.
A capacity crowd made for lively bidding, but 200+ bikes makes for a long day, and the crowd had thinned appreciably by the end of the evening. 
1975 Ducati 750SS, 'square case'.  Lovely machine.
A very rare Norton 'Hi-Riser' Commando 850cc.  When new, everyone threw out that seat and the handlebars...
Groovy original '74 Honda chopper.
Equally groovy 1895 Hildebrand and Wolfmuller, which sold for $140k+.
The 1911 Marvel was just that - the last motorcycle designed by Glenn Curtiss, who had already moved on to aircraft building. 
I thought initially this was a desmodromic valve system; both valves are positively opened have a controlled closing by a single push-pull rod from the timing chest.  The two-way rocker arm worked both valves.
The steel petrol and oil tanks were part of the frame.  It sold for $45,000.
The new owner of the BMW R51RS, who looks just a bit stunned to have paid $130,200 for his new bike (inclusive of buyer's premium). 
A Shriner's Honda 305cc Dream, complete with ceremonial sword.


occhiolungo said...

Hi Paul. The Marvel is a marvel, good point! My buddy Wes restored this one and an identical second bike at the same time. He later sold it to Mike Smith, then on to Otis Chandler. I'm not sure if Desmo is the right phrase, didn't they have no valve springs? But this is an interesting method of valve operation. I have a few more photos on my site of other similar bikes, with a short description of the mechanics of the push/pull rod.

see you soon.

The Vintagent said...

I do believe the push-pullrod has a 'c' cam follower, which means it is totally positive valve actuation, hence desmo. Otherwise one valve would never get over the pressure of the second valve spring - no?
I've never seen a desmo head without valve springs anyway - that last few thou gap needs positive closure for good compression.

occhiolungo said...

I've never played around with those post war Italian motors. too modern for me! :) But all the wiki pages and animations on the internet describe Desmo as using no valve springs.

Not a big deal either way, that Marvel is still a marvel, no matter what we call it. And the motor runs well too. Starts and idles easily enough, but I'm not sure how well it would breathe at (relatively) high rpms with the valves tied together. Wes is happy with these motors, and has several in his Curtiss and Marvel bikes.

Caterpillarnut said...

It's a unique valve system, though I have seen it on some stationary engines such as the "Baker Monitor" horizontal engines, or the Edwards farm engine. This is the first motorcycle I know of that used ths system.

However, it is not a desmodromic system by any means. A "push-pull rod" is a much more accurate description. The rockar arm and rod are positively actuated, but it is not positive valve actuation; there is a huge difference. The spring is the only thing that re-closes these valves. In response to your comment about the springs opposing each other, that cannot happen if the valves are properly lashed. The intake and exhaust valves exert no pressure on the rocker when they are not being opened, due to the valve lash. When one valve opens, the rocker tip for the other valve will move away from that respective valve.

The Vintagent said...

You're right; on close examination the valves are 'loose' - it appears at casual glance that the valves are positively actuated. It would have been easy actually to have made a desmo from this setup, as the push/pull rod is halfway there.
Desmos were patented in 1897, and I think the first cars to use the system were the Delage GP racers of 1914.

Boucher said...

This is the good blog with good images and good details. Please keep on posting the more stuff. I will like to hear more from you.

Carla said...

The 1911 Marvel is definitely a marvel, it's a real beauty. I wish i was there, really nice photos. Thanks for the share.