The "Three-Cylinder" Commando

P,S. the general layout externally is the same as the Commando, with 2 upright cylinders and the balance cylinder/kompressor down low at the front.

Since its a 2 stroke ( watercooled) the internal arrangements can only be guessed at....

Rohan,
The bike you show is NOT a singing saw. Though you may be right about the bike shown in your picture. Will enquire with a guy who has access to the works drawings- they still exist, and I know who has them.

http://www.iwvmcc.co.uk/news.php?active ... ews_id=147

Thanks Les. That diagram etc is actually for the single cylinder (twingle ?) supercharged DKW.
The pic I showed is a twin, so must be a little more complicated.
Herr Kluge won the Lightweight (250cc) TT in 1938 with a development of it, so it musta been good.

No "maybe" about it Joe, the pic I showed is proof, your Commando layout is based on that prewar DKW, whether the builder knew it or not !. And whether or not the blueprints still exist...

Cheers.

Rohan said:

That diagram etc is actually for the single cylinder (twingle ?) supercharged DKW.
The pic I showed is a twin, so must be a little more complicated.
Herr Kluge won the Lightweight (250cc) TT in 1938 with a development of it, so it musta been good.

Click to expand...

http://www.motorcyclespecs.co.za/model/ ... 0_1939.htm

A watercooled 250 c.c. two-stroke with three pistons, a rotary valve and only one sparking plug. That is part of the specification of the D.K.W. on which Ewald Kluge won the 1938 Lightweight T.T. by over ten minutes! In doing so he cracked round to raise the lap record almost 3 m.p.h. by clipping 57 sec. from it.

Basically his machine was virtually a split-single (like the Puch machines of post-war years) with watercooling and two rearward facing exhaust ports. A third piston, of considerably bigger diameter than the "working" pair, was fitted in a pumping cylinder that lay horizontally in line with the machine, forward of the crankcase. Above this, and forward of the watercooled block, was mounted a transverse rotary valve that had an Amal carburetter at each end\ Mixture was taken from both carburetters through the rotary valve to the big cylinder which was only a pump. This rammed the mixture into the working chamber—and out through the exhaust ports at slow speeds.

Click to expand...

The boundaries of what is a single and what is a twin get blurred ?
So are the cylinders beside each other or behind each other ?

very hard for me to say as a Ducati nutter but i am impressed , to see that Norton had the idea first before Ducati was somehing i never knew
that really is a piece of histery you have Joe

Rohan said:

The boundaries of what is a single and what is a twin get blurred ?
So are the cylinders beside each other or behind each other ?

Click to expand...

It seems you have reverted back to asking questions in Swahili once again.

Are the pistons beside or behind each other? Well, it would be a physical impossibily for the cylinders to be behind each other I would think, but perhaps one is behind the other.

I saw some kind of a 1930s two stroke twin with a supercharging third cylinder in the resto shop at Barber; as I recall it was a DKW; it had a stamped steel monocoque frame.

L.A.B. said:

Are the pistons beside or behind each other? Well, it would be a physical impossibily for the cylinders to be behind each other I would think, but perhaps one is behind the other.

Click to expand...

If you study those diagrams and contemplate their actions, that twingle has one cylinder in front of the other, and the piston at the front is trailing behind the action of the rear one. So that statement of being behind each other wasn't so inaccurate at all.....

Maybe it lost something in the translation from the Swahili though...

Some two stroke lore- just spoke to Stefan Knittel, classic motorcycle journalist, who rides all sorts of vintage exotica and works for the man who posesses all variants of the "Ladepumpe" DKWs, including the works racers (yes, and including a "singing saw", which is not a "Ladepumpe" bike). The twins (4 pistons!, 350 and 500cc) had the Ladepumpe UNDER the crankcase, some of the singles (as per illustration) had it at 90° to the working pistons. It must be pointed out there are two major differences to the "Commando Tripple" Jake:

1. The piston was not there to fight vibration, but to compress the fresh mixture;
2. What you take for a twin is actually technically considered a single (as on Puchs post-war), having a common combustion chamber, and with the bores BEHIND each other, so not a parallel twin by any stretch of imagination.

With the same justification you could point out any 90° twin- say Moto Guzzis- or 90° V4, the Ducati prototype from the 1960s, and say it was basically the same as the "Jake" layout. Again in these cases the front piston and conrod are there, are there at 90°s, but have a totally different function in a different engine layout.
Joe Seifert

Isnt there a saying about forests and trees .

They might not be entirely there for the same purpose , but they do in part do the same thing .

And AS FOR ' Journalists ' , infalible is like saying a Honda 750 is superior .

One tree makes a forrest?

My journalist friend Stefan Knittel has been a Norton man for about 4 decades and has a Norton collection spanning from pre-WW1 through his 1998 C652 International, with a couple of Commandos and Inters thrown in. Not your AC kind of character hailing even the deadest duck he just happens to sit on.
Besides he has written the best motorcycle manufacturers history book I have ever read, though unfortunately on BMW, integrating political and economic background, something gladly forgotten by most others who loudly speculate on a certain year's colour scheme instead.

AND he will gladly admit the fascination of a Honda 750 escapes him.

ZFD said:

1. The piston was not there to fight vibration, but to compress the fresh mixture;

Click to expand...

The pumping piston would have to be part of the engine balancing equation.
Especially given the size (and weight) of it....
Can't imagine the designers left anything to chance, or totally ignored that aspect of it ?

ZFD said:

One tree makes a forrest?

My journalist friend Stefan Knittel has been a Norton man for about 4 decades and has a Norton collection spanning from pre-WW1 through his 1998 C652 International, with a couple of Commandos and Inters thrown in. Not your AC kind of character hailing even the deadest duck he just happens to sit on.
Besides he has written the best motorcycle manufacturers history book I have ever read, though unfortunately on BMW, integrating political and economic background, something gladly forgotten by most others who loudly speculate on a certain year's colour scheme instead.

AND he will gladly admit the fascination of a Honda 750 escapes him.

Click to expand...

Mr Stefan Knittel is indeed not just A jounalist , something people from across the see might not know
I build my domi model 88 1654 based on pictures of one of his articles and believe me , he knows his stuff
ps i am not the hero worshipping type but credit where it is due