Oddball engines and prototypes

[tjbw]

Someone mentioned BSA somewhere?

Here's a prototype 250cc near horizontal single. Features include 4 radial valves, 2 carbs, 2 exhausts, monoshock rear suspension. 'Management' decided not to put it into production.

It's on display at the National Motorcycle Museum near Birmingham, UK.

[tjbw]

Here's a little scooter, produced by Excelsior in 1942 and 1943, for delivery by parachute!

I guess they were easier to pack, than to ride off-road.

This is on display at National Motorcycle Museum, near Birmingham UK.

[husaberg]

Someone mentioned BSA somewhere?

Here's a prototype 250cc near horizontal single. Features include 4 radial valves, 2 carbs, 2 exhausts, monoshock rear suspension. 'Management' decided not to put it into production.

It's on display at the National Motorcycle Museum near Birmingham, UK.

Management refused to race it unless the designer hele could guarantee it would 100% win in its first race meeting.
Someone in NZ was going to make a replica

[Grumph]

Management refused to race it unless the designer hele could guarantee it would 100% win in its first race meeting.
Someone in NZ was going to make a replica

They did - it's effectively a horizontal Goldie motor in a close copy frame.

[husaberg]

They did - it's effectively a horizontal Goldie motor in a close copy frame.

No GPR boys father was talking about doing one.

[WilDun]

Very interesting machine, Geoff Duke tried it and was very keen to race (who could have been a better rider for it?) but the high handed way in which it was scuppered was just another nail in the coffin for the British motorcycle industry! - none so blind as those who will not see!
Then on the other hand, we don't know the whole story (politics, country trying to recover financially from WW2 and at the same time paying back lend lease money, while Japan and Germany were being being rebuilt by the US, - times were tight, big handicap!

The brilliant Doug Hele ended his working days with British Seagull (now long gone).
Better news, it seems now that Triumph are back at the top again, taking over from Honda as engine suppliers in Moto GP in the Moto 2 class with their triple (700?) .

[guyhockley]

If you want to supercharge an engine, you must blow through the port that closest last. In a four-stroke engine that's no problem, but supercharging a two-stroke tends to be less effective. You blow through the transfer ports, but when these close, the exhaust port is still open, so you cannot really create a high pressure in the cylinder.

Closing the exhaust port before the transfer ports was done in the pre-war blown DKW racers with their split-single layout and in the Jumo 205 uniflow engines
with a crankshaft at either end of the cylinders. But as supercharging was forbidden after the war, nobody seems to have given it much thought since then.

I knew that Motobecane had experimented with a DKW type engine, but I was looking through some books I was given in Belgium and discovered I have a manual for the production version!



Bore and stroke are 39 x 41,8, balance/charging piston (the manual can't seem to decide which to call it) is 62 x 13, "as the stroke is so short, the cast-iron charging piston is very heavy to achieve satisfactory balance". It has a deep recess to reduce pumping losses, I assume that's the dotted line in the diagram.
Comparing it to the standard model with the same 13mm carb, that gives 2,10ch @5500, torque peak @ 3500.
Port timing: Exhaust 150 degrees standard, 127 degrees "blown".
Transfer 104 degrees standard, 92 degrees 20' "blown".
Standard motor is piston ported. No idea if the exhaust and/or silencer is different.
Text comments on this being a lot of work for such a small power gain, but explains that it's a moped with a legal top speed of 45kmh. Says this model has 50% more torque and similar fuel consumption to the rest of the range (330 - 370 g.ch/h).
So, not quite a DKW! I'm sure I've seen a picture of an experimental trials bike (Bultaco or Montesa?) using the same idea...

[ken seeber]

I think it was Bultaco, but the pumper piston was at 90 deg to the engine cylinder bore, however I don't know what the phasing was. Possibly for a trials bike where they were chasing improved low speed torque.

[WilDun]

I think it was Bultaco, but the pumper piston was at 90 deg to the engine cylinder bore, however I don't know what the phasing was. Possibly for a trials bike where they were chasing improved low speed torque.

Yes, that was a Montesa (I think Mr Bulto originally worked for Montesa)
Concentric pin layout (to me) seems to produce compatible phasing - with cylinders at 90 deg. (a little difficult for experimenting if you had to move the pump cylinder axis to change the phasing though!).

)

[Pursang]

Here's a little scooter, produced by Excelsior in 1942 and 1943, for delivery by parachute!

I guess they were easier to pack, than to ride off-road.

This is on display at National Motorcycle Museum, near Birmingham UK.

My First motorcycle, built around the mighty Villiers Junior Deluxe.

https://s3.amazonaws.com/WEBPOSTS/OZ...6+Number+2.jpg

Sorry, You'll need to click the link, the insert image box doesn't like the URL ???

[Niels Abildgaard]

Yes, that was a Montesa (I think Mr Bulto originally worked for Montesa)
Concentric pin layout (to me) seems to produce compatible phasing - with cylinders at 90 deg. (a little difficult for experimenting if you had to move the pump cylinder axis to change the phasing though!).

)

Two strokes are only for ships,mopeds and chainsaws.
Mopeds and saws have noise and vibration problems.
Balance from a V2 scheme is almost perfect.
Noise is a big problem.
Let us divide the Exhaust in two ports one over the other.
The upper exhaust port can be connected to the unused frontchamber of the pumping cylinder ,that sucks and contain the violent blowdown and noise.
The lower port goes to athmosphere without to much hindrance.Very compact but I need to find a material that will be able to act as exhaust outlet reed valve for the pumping cylinder front.

[WilDun]

Balance from a V2 scheme is almost perfect.
Noise is a big problem.........
Let us divide the Exhaust in two ports one over the other.........

Maybe the pump could also suck in a little air as well, to use up the rest of that unburnt mixture we are always hearing about and also produce power (to some degree)!

Any engine two or for stroke will find its niche of course but lets not decide to put them in little compartments and specify what they should be used for! (let them find that niche themselves) unlike what H***a and D***A have gone and done for four strokes (eh Frits ).

PURSANG, wasn't that little bike called the "Corgi" - they used to drop both them and the Royal Enfield RE1 (with its DKW inspired engine) to the troops in Europe.

[husaberg]

I think it was Bultaco, but the pumper piston was at 90 deg to the engine cylinder bore, however I don't know what the phasing was. Possibly for a trials bike where they were chasing improved low speed torque.

I drew up something similar 20 years ago i had the crankpin phased at from memory 90 degrees and the v 90 also. (It might have been 45 degree phasing)

I think the idea was to have a large crankcase but normal primary compression.
The layout was similar to the piston supercharged DKW but the timing was different (from memory anyway?)
It had coloured felt pen an all.

I knew that Motobecane had experimented with a DKW type engine, but I was looking through some books I was given in Belgium and discovered I have a manual for the production version!



Bore and stroke are 39 x 41,8, balance/charging piston (the manual can't seem to decide which to call it) is 62 x 13, "as the stroke is so short, the cast-iron charging piston is very heavy to achieve satisfactory balance". It has a deep recess to reduce pumping losses, I assume that's the dotted line in the diagram.
Comparing it to the standard model with the same 13mm carb, that gives 2,10ch @5500, torque peak @ 3500.
Port timing: Exhaust 150 degrees standard, 127 degrees "blown".
Transfer 104 degrees standard, 92 degrees 20' "blown".
Standard motor is piston ported. No idea if the exhaust and/or silencer is different.
Text comments on this being a lot of work for such a small power gain, but explains that it's a moped with a legal top speed of 45kmh. Says this model has 50% more torque and similar fuel consumption to the rest of the range (330 - 370 g.ch/h).
So, not quite a DKW! I'm sure I've seen a picture of an experimental trials bike (Bultaco or Montesa?) using the same idea...

That layout looks like the DKW ORe engine

1928


http://4.bp.blogspot.com/-h8s_uWPOwx...ORe+engine.jpg


http://www.odd-bike.com/2014/02/dkw-...force-fed.html

[Pursang]

https://s3.amazonaws.com/WEBPOSTS/OZ...ust+design.jpg

So simple! Like a Comprex, but No moving parts

180 degree twin. Bleed down pressure transferred to charge side increasing recharge pressure and volume .

Lengths and volumes adjusted to ensure no combustion gasses transferred to either cylinder.

For a parallel twin just put a U-bend at the centre bleed down point.

(In the real world, (wherever that is), it will undoubtedly need asymmetric timings or different strokes or electronic control, or something)

cheers, Daryl

[Pursang]

PURSANG, wasn't that little bike called the "Corgi" - they used to drop both them and the Royal Enfield RE1 (with its DKW inspired engine) to the troops in Europe.

I think the military one was a "Welbike" (worth a google) & the civilian was a Corgi.

Mine was a home-built minibike with wheel barrow wheels and the engine out of a Malvern Star auto-cycle. (also worth a google)
The tank off the auto-cycle is on the other bike, it's a cut-down Victoria 'Nicky' scooter.

Cheers, Daryl.