Two into One

[Guesi]

Here is the prescription , but only in german. When I find the time I will translate it...

[breakwellmz]

How Allen Millyard made a 500 twin - https://www.youtube.com/watch?v=lu5q_3nwEhU

[Puffs]

Well, I'd guess you'd have to sacrifice one of the bikes you already have & add/combine parts from the spare engine? Then you might relax on the legal angle, but it will not be entirely kosher.

No doubt a crankshaft can be pressed with a newly made centre pin, which would include 1 or 2 centre bearings. A sealing separation holding that bearing(s) would also be required, or a horizontally split crankcase. A 180° piston orientation is best for balancing, although if they are too far apart you still get rocking-couple vibes. A 0° layout does not require pressure isolation and is therefore easier, but I think 180° is more common & more desirable. And then you'd need to enhance the frame & suspension, and indeed the brakes. Clutch? Gearbox? Quite a bit of engineering, and work too.

I always craved to have such a (G)T500, but it never happened. Did ride Kawa's 500 triple though. But in the air-cooled 2T twins, possibly Yamaha's RD's were best.

Before I press the 'Submit' button, I always first do a ctrl+a and then ctrl+c, so that what I typed is in the copy buffer. If I get timed-out, so that I would have lost all I typed, I can then do ctrl+v and have it all back.

[AlanJ]

Hi Puffs,
Yes, the first shallow thought was as I said earlier, to use the newly built Saxon or maybe the original Saxon, but as you mentioned it would need better brakes, namely the front, not on cast wheels though, so, a new set of wheels, then the next bit is the footrests and as you now know on the Saxon
they are quite complex compaired to an ETZ system. I think one would have a much better shot starting with an ETZ 251 as I said earlier. Again, when you look at what has already been done before, and there are quite a few now, I have only seen 500's on ETZ's, mind you, some bright spark will mention that the Saxon already has a 500, but.
Alan.

[AlanJ]

Hi Guesi,
Thanks for all the info, I have tried to translate the article myself, but at the moment it's not happening. 20 or so years ago I spent the last 4 years of my working life in Saarlouis Fordwerke and the trouble there is all my German colleagues wanted to enhance their English so I lost out a bit.
Alan.

[Guesi]

So I try a fast translation:

Two complete engine crankcases were changed in a way that they form one compact engine unit so they look as a symetric unit.

Both engines were shortened (cut) on the inner side (middle of the engine).
The left engine contains the complete primary drive, clutch and the 5-gearbox.
On the right enginee, the gearbox case was cut off so there remains only the basic crankcase for the crankshaft.

Both engine housings got a flange with centering tubes so the two housings can be connected exactly.
The 2 crankshafts (ETZ 250 parts) remain in the factory made condition except the 2 crankpins pointing towards the center of the engine.
These crankpins were repaced by cylindric crankpins that were connected by 4 woodruf pins in 4 keyways on each crankpin and a cylindric bush with 4 keyways on each end that was pushed over the crankpins.

To tighten the cylindric bush the bush has a cutting on each side and can be tightened with a clamp.

When assembling the engine both engines will be mounted together with the 2 crankshafts.
The clamps can be reached by a small hole in the engine housing so the clamps can be tightened after the engine is completed.

As the engine is symetric in the frame, there is the need to install a longer pinion shaft to meet the chain sprocket.
This pinion shaft must be produced . As it is longer, a 3rd bearing (6304 JC4) is installed to give the pinion shaft more stability. For the bearing seating of this bearing a part of the right gearbox (the one that was cut off) is used and it is connected by a new oil tunnel to the gearbox for lubrification.



I hope it is understandable for you

[AlanJ]

Hi Guesi,
Absolutely great. Do you know if this info comes from someone actually building this engine or is it theoretical?
Alan.

[AlanJ]

Sorry Guesi, I was forgetting the picture.
Alan.

[Blurredman]

I wonder if they'd be much of a difference if the two cylinders were 300cc...

[AlanJ]

Hi M,
I wouldn't have thought so. I could use the 300 engine as the l/h and the 251 for the r/h, trouble is talking it through with you guys, I don't think the
Saxon would be the best bike to use.
Alan.

[Puffs]

If you worry about the F wheel & an extra disk, using a different wheel really is only a minor issue, compared to everything else that's required. But I'd be quite reluctant to sacrifice any fine working bike.

On using a 300: particularly if it's an 180° twin, like in Guesi's earlier Bild 1, you'd want the same weight of pistons on either side. The 2•40cc extra will make it slightly more potent.

[DAVID THOMPSON]

the fellow doing the machine shop part of this
needs to be served an extra case of beer
for his work

[AlanJ]

Hi Puffs,
You are right, there is no way I would use dissimilar engines, the 300 below the cylinders are the same, I think, and if that is so, then you could go either way, a 500 or a 600, it's just which barrel and head you choose as the master, then buy the same to make a pair. To be honest though, I don't think I want to arse up an engine that has just been sorted. As i said, what I could do with is a complete ETZ 251, trouble is there is nothing showing at the moment.
stay safe Alan.

[Puffs]

Tying in to what David said: I think this project will only be viable if you can do virtually all the work yourself, and if you'd get your reward just from doing that. So if you're in it for the journey, rather than for the end result.

But you'd still have to buy quite a bit, and nobody can do everything - some money will change hands.

[AlanJ]

Good morning All,
I only wish I had the machinery to do all the work, I can certainly cut the crankcase up and position it for welding but sadly I will have to
have an extended main shaft/ final drive machined, not cheap There is a way of joining the two cranks that is not over expensive, namely a Bowex-M-32
or similar. (Thanks Thomas Scott ). I feel the way to go at the moment is to buy an ETZ 251 complete, but if an ETZ 251 engine becomes available then
I would/will sort the engine first, and if I go engine first then I can look at joining with the Saxon after.
Stay safe Alan.