ESE's works engine tuner

[marsheng]

You voted Trump.

Classic !!!!

[husaberg]

Classic !!!!

What size are the seals Wallace? being German they will be metric, my bet is as there is only so many different metric bearings and shaft combos they will be shared by quite a few other Japanese bikes.

[marsheng]

What size are the seals Wallace?

52x32x7 or 8 or 9

I found a chap down the road who was rebuilding his Maico and had some seals. So I have borrowed these and will order from Socamaico in the US. However, an alternative will always be good to know.

Cheers Wallace..

[husaberg]

52x32x7 or 8 or 9

I found a chap down the road who was rebuilding his Maico and had some seals. So I have borrowed these and will order from Socamaico in the US. However, an alternative will always be good to know.

Cheers Wallace..

Doesn't match any bikes in the PRO X cattledog.
http://www.pro-x.com/wp-content/uplo...ech_online.pdf

Talked to an old American guy from Nevada who sold Suzukis and when the first fast six speed Suzuki twins came out, (T20) they tried them in desert racing but used the arrangement you are discussing (pistons rising and falling together) and called them "Twingles".

i would say they did it that way for power delivery
Ossa doubled up 250-500cc desert racing twin had to configure the crank the same, but that was due to the cylinders being so wide apart being a aircooled 500cc two stroke that the width caused a massive rocking vibration, the doubled up 500cc Greeves was the same.
Yamahas RD350 and RD400 twins never had the issue as they used narrow poxy transfers.
Suzuki got around this on the Cobra/Titan by offesting the transfers so they overlapped.

[WilDun]

Will, Twingle is also a name used for 'split single' a twin uniflow twostroke, with shared combustion chamber.

https://en.wikipedia.org/wiki/Split-single

There have been quite a few examples of those tried in the past, mostly having a conrod with a link for the rear piston however, they didn't seem to be worth the effort -
I think maybe Puch had the most successful one but there was an experimental one somewhere with twin (tandem) geared cranks and the cylinders tilted towards each other (no doubt for a more compact CC but quite similar to the animation though) - eventually it just faded away (using the excuse that the head was porous!).

Maybe a good subject for ("oddball") - eh?

[Frits Overmars]

There was an experimental one somewhere with twin (tandem) geared cranks and the cylinders tilted towards each other (no doubt for a more compact CC but quite similar to the animation though) - eventually it just faded away (using the excuse that the head was porous!).

They didn't need an excuse; the FIM provided one when it banned blowers in racing.

[Niels Abildgaard]

They didn't need an excuse; the FIM provided one when it banned blowers in racing.

Very interesting.It can be even better than present normal two strokers with a tuned exhaust instead of that blowerthing
The amount of air/petrol mixture for a given power will be less due to the long,long cylinder and exhaust temperature will be higher.
But the exhaust piston also gets much hotter.
Aint no free lunch.
It will also make a better air powerplant.
Gyros and ultraligth trikes has a single ca 1.8 meter prop directly behind pilot where incoming air is let us say disturbed.
It gives a very powerfull torque reaction variation when power changes.Two 1.25 meter counterturning props side by side will be more efficient,no torque and almost vibration free.

[WilDun]

They didn't need an excuse; the FIM provided one when it banned blowers in racing.

The one I was thinking of was obviously inspired by the one in the pictures, think it was in UK in the seventies - it didn't seem progress further than the prototype stage (probably had a more realistic bore/stroke ratio than the one in the pic!). There looks to be quite a bit of 'lag' on the inlet piston!
Peripheral speeds on those gears might have been a problem too!

[peewee]

52x32x7 or 8 or 9

I found a chap down the road who was rebuilding his Maico and had some seals. So I have borrowed these and will order from Socamaico in the US. However, an alternative will always be good to know.

Cheers Wallace..

your in luck mate. the ktm 550 and 440 dirt bikes from the mid 90's used a 52x32x7 crank seal on the water pump side (left hand side). you can look it up on any ktm parts fishe that goes back to '96 and earlier. 0760325272 part#. it is only a single spring seal but it does a fine job of keeping gear oil out of the crankhouse. ive had a few of these engines over the years and never once has one leaked . let me know if you cant get one. their $18usd and I could have it in 2days and ship it over, not sure how much extra that would cost however. https://ktmpartsonline.com/ktm-part-.../0760325272/1/ http://www.ktmonlineparts.com.au/par...72#contentArea

[Frits Overmars]

The one I was thinking of was obviously inspired by the one in the pictures, think it was in UK in the seventies - it didn't seem progress further than the prototype stage (probably had a more realistic bore/stroke ratio than the one in the pic!). There looks to be quite a bit of 'lag' on the inlet piston! Peripheral speeds on those gears might have been a problem too!

Those split-single (and split-twin) double-piston engines were generally long-stroke jobs Will, even the all-conquering DKWs of that era. And the lag on the inlet piston is just that, although the designers preferred to talk about the lead of the exhaust piston: open the exhausts early in order to provide sufficient blowdown, and close them early in order to give the compresor a chance to supercharge the cylinder during the time that the exhausts are closed again and the transfers are still open.
This picture shows the crank angle phase difference in their last blown double-piston design: exhaust (left-side piston) closed, transfer (right-side piston) still open.


In theory the early-closing exhaust should limit scavenging losses as well; in practice the scavenging pressure washed massive amounts of fuel right through the engine, helped by the suction of the ear-splitting megaphone exhaust pipes. You'll understand the peculiar size of those DKW petrol tanks, knowing that they consumed one litre every 5 kilometers.


The peripheral speeds on those gears were no problem. The coupling gears on Rotax tandemtwins and Aprilia V-twins have a bigger diameter than their crankshafts,
plus they run at double the revs of those old split-singles.

[WilDun]

i would say they did it that way for power delivery
Ossa doubled up 250-500cc desert racing twin had to configure the crank the same, but that was due to the cylinders being so wide apart being a aircooled 500cc two stroke that the width caused a massive rocking vibration,........Yamahas RD350 and RD400 twins never had the issue as they used narrow poxy transfers.
Suzuki got around this on the Cobra/Titan by offesting the transfers so they overlapped.

Yes, I used to wonder why Suzuki used that layout on the T500, but in hindsight it was good design. BTW I remember when it was first sold in the US it was advertised as being "The world's first 500cc Dual Stroke"!

[Tbh37620]

This ran over a welded in central port bridge that had added boost ports down each side.

Wobbly, do you have any photos or info on this welded in bridge(Parent materials, filler metal, etc)? I have several cylinders I would like to weld bridges into to expand the width of the ports. Id imagine the H1 cylinder was a cast iron sleeve in aluminum casting?


Thanks,

[wobbly]

The cylinder we used was a TZ250G model as this had by far the most modern port/tunnel layout of any of Yamahas old version twins.
We used a 58 stroker crank from a Banshee and I balanced that to use 61.5mm H1 pistons ( top ring only ) to stay at the 350cc limit.
You will have to talk to the plater you will be using,each has a preference for the weld and filler plate material.
Here in NZ they want 6061 - but Millenium is different again.

[Tbh37620]

The cylinder we used was a TZ250G model as this had by far the most modern port/tunnel layout of any of Yamahas old version twins.
We used a 58 stroker crank from a Banshee and I balanced that to use 61.5mm H1 pistons ( top ring only ) to stay at the 350cc limit.
You will have to talk to the plater you will be using,each has a preference for the weld and filler plate material.
Here in NZ they want 6061 - but Millenium is different again.

Thank you for that info. Have you ever successfully welded an exhaust bridge into an aluminum cylinder with an iron sleeve? Maybe it couldn't even be done but figured I would ask. Thanks again

[F5 Dave]

One might be tempted to bore out the iron. Weld in super generous ally bridge and slide a accurate sleeve in place maybe of ally then grind sparingly allowing for relief on the bridge before and after plating it as still will be crappy heat transfer in a very hot position. You will be water cooling them of course . .

Never tried it but in same position on bucket I chose to bore triple port so cast in steel connected to ally as stock and allows for thicker bridge between ports.

Of course with skinny through hole retained barrels these ports can be difficult but some alternative engineering can sidestep the original constraints some of which have been posted before.