ESE's works engine tuner

[guyhockley]

plus some more MZ

https://www.kiwibiker.co.nz/forums/s...post1130411899

The page this links to also has a picture of a 1962 Kreidler with twin rotary discs so also older than the kart engine I posted... I'll get me coat

[2T Institute]

Then this chaos might look familiar .
Attachment 329433

A bit more than a Rotax barrel there

[husaberg]

The page this links to also has a picture of a 1962 Kreidler with twin rotary discs so also older than the kart engine I posted... I'll get me coat

Yeah i have posted a write up on it before and Frits has posted pictures of it as well.
https://www.kiwibiker.co.nz/forums/s...post1130412381
my word that took some finding.
https://www.kiwibiker.co.nz/forums/a...p?albumid=4915

Well if we're assured it's three rotary discs, are they inside the crankcase chambers ? Looking at the angled inlets, If the discs are inside - with one crankweb cut away - and the inlet ports come into each crank chamber at an angle, that would explain the layout.
I've seen a similar internal disc in one of Irvings books - used in a cyclemotor of about 30cc.

Or an apha

or an even odder version anzani
https://www.kiwibiker.co.nz/forums/s...post1130150906

[Grumph]

Using the OD of the crank as a rotary valve like the Alpha is straight Vespa practise.

I'm still looking for the pic of the cyclemotor with a disc valve keyed to the shaft, inside the crank chamber, with the inlet coming in from the side.

If you've got "pork chop" shaped flywheels it's one way of doing a rotary valve with little alteration to the engine.
Disc diameter is of course limited to that of the crank OD.

[husaberg]

Using the OD of the crank as a rotary valve like the Alpha is straight Vespa practise.

I'm still looking for the pic of the cyclemotor with a disc valve keyed to the shaft, inside the crank chamber, with the inlet coming in from the side.

If you've got "pork chop" shaped flywheels it's one way of doing a rotary valve with little alteration to the engine.
Disc diameter is of course limited to that of the crank OD.

I have posted it but after spending so much time looking for that last set of Kreidler pics i are not looking for it in my pics posted.
i will have a google.

There is a good pic in the Draper two stroke book but i think its upstairs.


There is of course that vairation of the through disk that the 2 stroke triumphs used (Zee german ones) pretty sure DKW used it as well for a while.

[WilDun]

Using the OD of the crank as a rotary valve like the Alpha is straight Vespa practise.

I'm still looking for the pic of the cyclemotor with a disc valve keyed to the shaft, inside the crank chamber, with the inlet coming in from the side.

If you've got "pork chop" shaped flywheels it's one way of doing a rotary valve with little alteration to the engine.
Disc diameter is of course limited to that of the crank OD.

GRUMPH -I think you are looking for the "Cyclemaster" engine which was fitted inside a bicycle rear wheel - that little engine above I think is basically the same engine in a moped frame, but the Cyclemaster was really compact and quite clever really!
Will look for the pics of it I have somewhere. - I used to own own one long long ago and was intrigued by the rotary valve (because it was like the MZ which was cutting edge technology in those days!

[husaberg]

GRUMPH -I think you are looking for the "Cyclemaster" engine which was fitted inside a bicycle rear wheel - that little engine above I think is basically the same engine in a moped frame, but the Cyclemaster was really compact and quite clever really!
Will look for the pics of it I have somewhere. - I used to own own one long long ago and was intrigued by the rotary valve (because it was like the MZ which was cutting edge technology in those days!

this one mainly shows the gear box thingy (its technical name) but in the background it can nearly be seen
Its correct name is the Norman Cyclemate cyclemaster

[Grumph]

There is a good pic in the Draper two stroke book but i think its upstairs.

GRUMPH -I think you are looking for the "Cyclemaster" engine which was fitted inside a bicycle rear wheel - that little engine above I think is basically the same engine in a moped frame, but the Cyclemaster was really compact and quite clever really!
Will look for the pics of it I have somewhere. - I used to own own one long long ago and was intrigued by the rotary valve (because it was like the MZ which was cutting edge technology in those days!

You're both correct - it's the Cyclemaster - and the pic is in Draper's book. Can you scan your copy Husa ? It's an odd setup with drawbacks but looking at the inlet port angles on that MZ, it wouldn't surprise me if that's how it's done. The layout with internal discs has the benefit of giving a crank the same length as a piston port engine. If the MZ was a peripheral valve - like the Vespa and Alpha - I'd have thought the inlets would be pretty well straight in and not angled as the MZ is.

Edit - just looked at the last pic. Gives the idea, if you want to the Draper pic is a little clearer.

[ken seeber]

All in all, I think as soon as gasoline DI injection technology has reached a level of 500 bar in serial application (500 bar is what F1 is currently running), and CFD computing power is available abundantly, too, one could give it a try. On the other hand, adapting today's car technology one could already get a quite clean two-stroke, only that it's "clean" area of the engine map woud be somewhat revs and power limited.

Haufen, I must say I do wonder if 500 MPA is feasible or the only way to go for CHDI. Undoubtedly it must offer improved atomization (presuming the nozzle spray details have been designed correctly), but it certainly comes at a price of high fuel pump costs, much finer filtration, possibly more power to overcome the extra forces and increased latency.
As to alternatives, don’t forget air assisted injection. In addition to Orbital’s system, Piaggio also did a version and was produced for a while on 50 c scooters (maybe called the FAST) under a programme run by a Marco Nuti. This used a small compressor mounted on the head, discharging via a small passive conical outlet valve. The beauty of this was that it essentially could be made to run at any speed the engine could go. Happen to have a head here:




On a different topic, have the Draper book, so here is the pic of the Cyclemaster valve. Also don’t forget the cutaway crank as used on Vespas for are radial entry. I remember seeing a pic somewhere when Orbital was mucking about with Bajaj (who made Indian Vespas). This showed a complete crank assy (inc rod) all wrapped up prior to the final assy grind of the OØ of the cutaway crank half, presumably for greater running trueness to allow smaller clearances and hence, improved sealing. If the springs were light enough, the valve could also possibly act as a “reed” valve, albeit a shitty flow path.

[WilDun]

That's the Cyclemaster pic I was looking for! but couldn't find it.
The Alpha engine pictured earlier ended up in a fire (the whole bike was burnt out). Looked a very promising machine in my day, very narrow for a twin disc engine (it was twin cylinder of course). Then Japan turned up the gas and all that stuff just disappeared, but I think that Cyclemaster possibly was a Dutch idea originally ?? - not really sure, but I think they may even have beaten MZ to the disc valve concept!

[ken seeber]

That's the Cyclemaster pic I was looking for! but couldn't find it.
but I think that Cyclemaster possibly was a Dutch idea originally ??

Will, Will, Will...

Who's going to get a big head now ????????

[tjbw]

That's the Cyclemaster pic I was looking for! but couldn't find it.

...

Cyclemaster possibly was a Dutch idea originally ?? - not really sure, but I think they may even have beaten MZ to the disc valve concept!

To quote Frits "disc valves were patented in 1918 by the british Sun company who actually raced their 250 cc disc-valver in the 1921 TT on the Isle of Man"

Cyclemasters were made by EMI in London, the design was based on drawings by DKW.

Cyclemaster history here:

http://www.users.globalnet.co.uk/~pa...cc/arc0322.htm

[WilDun]

Oh.........Well.......there you go! and I normally know everything!
At least that certain person won't be getting big headed!

[tjbw]

Oh.........Well.......there you go! and I normally know everything!

...

I know how you feel. I had thought that Daniel Zimmerman made the first disc valve engine.

https://www.500race.org/web/Marques/Zimmerman.htm

[Frits Overmars]

I think that Cyclemaster possibly was a Dutch idea originally ... I think they may even have beaten MZ to the disc valve concept!

Will, Will, Will... Who's going to get a big head now ????????

Who, me? In any case not because we beat MZ to the disc valve concept. There was nothing to beat there, as tjwb wrote:

To quote Frits "disc valves were patented in 1918 by the british Sun company who actually raced their 250 cc disc-valver in the 1921 TT on the Isle of Man"
Cyclemaster history here: http://www.users.globalnet.co.uk/~pa...cc/arc0322.htm

The cyclemaster history reveals that it was based on the Dutch-built Berini engine, one of the engines I tuned as a youngster. And tuning it was quite easy.
It surprised me that nobody commented on the red circles in Husabergs Cyclemaster picture, showing the engine's most interesting part: the governor.
It was a spring-loaded vane that gradually closed the inlet opening in the disc as the revs went up. Removing the vane gave the little engine a second wind.



Back to Grumphs original question about the inlet discs in the MZ triple.

Well if we're assured it's three rotary discs, are they inside the crankcase chambers ? Looking at the angled inlets, If the discs are inside - with one crankweb cut away - and the inlet ports come into each crank chamber at an angle, that would explain the layout. I've seen a similar internal disc in one of Irvings books - used in a cyclemotor of about 30cc.

MZ wouldn't let me pull the triple apart for pictures, but I see engines with similar internal discs every day in the streets of the former German Democratic Republic.
Yep, the Trabant. It has one carburetter serving two discs as shown in the pics below.