ESE's works engine tuner

[dutchpower]

50 cc is tested but has not the expected HP

[husaberg]

Hi Frits,

Maybe you know something about this "half moon" plates in this titanium YZR 500 headpipes. I can only guess.

Thanks

Det buttons we have talked about them before.
here. later
https://www.kiwibiker.co.nz/forums/s...post1130263736
https://www.kiwibiker.co.nz/forums/s...post1130792235

[katinas]

Det buttons we have talked about them before.
here. later
i can't find it.

Thank you, I missed

[husaberg]

Thank you, I missed

No Worries, it comes up about every year or so.
I am glad to help, I really enjoy your work.
I have added some links above

[lucf]

Some may think I am like Luc, talking up shit to justify myself, .........................

Thanks !!

[katinas]

As Katinas wrote earlier, nor his engine, nor the Ryger has auxiliary exhaust ports because those would require a wider piston skirt, that would in turn hamper the flow into the transfers. Since I read it here, I can react without endangering my NDA (thank you Katinas). And what follows now, is purely my own guesswork since I never received any relevant information from Ryger.
From the Ryger homologation papers we can see that the exhaust timing is lower than the Aprilia RSA timing, so the Ryger's blowdown angle.area is tiny compared to the RSA's. And when taking the initially quoted maximum torque rpm of 17500 into account, the Ryger's blowdown time.area was almost non-existent. It nevertheless did not stop it from producing over 70 hp.
And before anybody says that they've never seen any proof of this amount of power in the form of a real dyno graph, let me say that neither have I, but I was lucky enough to get a seat-of-the-pants impression of the original Ryger prototype before problems with the production engines brought the operation to a halt, and my pants are not that easily fooled, having ridden motorcycles with several hundred hp.
By the way, what made me decide to step out of the project, was the lack of frankness. I would have loved to take part in the development of that engine, but it turned out that I was only recruited to generate publicity. I'm sure I could have prevented some of those technical problems if only there had been an exchange of thoughts, but all I ever got were promises. It's a pity....

OK, back to my theory. Seeing that the in-cylinder pressure of the RSA is about 12 bar at exhaust opening, and given that the Ryger is claimed to produce about 20 hp more than the RSA, and given that the Ryger's blowdown time.area is so much smaller, there must be a huge amount of spent gases that enter the Ryger's transfer ducts, raising the pressure in the sub-piston volume and the density of the mixture (well observed, Philou). The higher pressure may lead to a much faster transfer flow, with more mixture inertia. This inertia then ought to pull more fresh mixture through the reed inlet valve.
I only wonder how effective this inertia can function, as the Ryger's transfer ducts are very short and anything but flow-encouraging.

That was also my second impression after the staggering acceleration: the beautiful sound. When you would expect a regular 125 cc engine to reach the end of its power band, the Ryger started to sing; that's the best I can describe it. This lovely sound, in combination with the large amount of hot exhaust gas that enters the transfer ducts and is subsequently recycled into the cylinder, made me think in the direction of Homogeneous Charge Compression Ignition with its very fast, short combustion phase; maybe ten times as fast as regular spark-ignited combustion. HCCI would also account for low fuel consumption, comparatively clean exhaust gases, and the need for only a small cooler, although I could not verify these claims.

Could you persuade your software to take a look at these thoughts, Neels?

Very likely, that spent gases began firstly enter sub-piston volume through fifth transfer window. .

[Frits Overmars]

Very likely, that spent gases began firstly enter sub-piston volume through fifth transfer window.

That would be a perfect example of history repeating itself. Suzuki used this idea in 1962; they made the third transfer port of their 50 cc works racer as high as the exhaust port, with the intention of pressurizing the crankcase. But in 1963 this third transfer port was no longer any higher than the others...

[shnaggs]

Fritz, If your theory is correct about the Ryger, wouldn't the hot spent gasses ignite the inlet mixture that is in the sub-piston area? Also if this theory is true, wouldn't that method play havoc on a reed valve?

I think I have mentioned this before, but what if we do the same thing, but use the returning pressure wave from the exhaust but shoot it down into the sub-piston area when the pipe tuning is working against itself. You could have a valve in the exhaust that would route the pressure to the sub-port, and then have another reed valve to keep the pressure in the sub-piston.

[Frits Overmars]

Fritz, If your theory is correct about the Ryger, wouldn't the hot spent gasses ignite the inlet mixture that is in the sub-piston area? Also if this theory is true, wouldn't that method play havoc on a reed valve?

My theory may be incorrect Shnaggz; I'm just guessing and trying to stimulate the brains around here.

I think I have mentioned this before, but what if we do the same thing, but use the returning pressure wave from the exhaust but shoot it down into the sub-piston area when the pipe tuning is working against itself. You could have a valve in the exhaust that would route the pressure to the sub-port, and then have another reed valve to keep the pressure in the sub-piston.

Yes, you did mention this before. That falsely-timed returning wave from the exhaust would arrive back at the cylinder somewhere between BDC and transfer closure, or even before BDC at low revs. It might work. But it would require a valve that switches in the tiny, almost non-existent period of time between the end of the suction wave and the beginning of the returning pressure wave, with the frequency of the crankshaft rotation, at some rpm values but not at others. Not so simple...

[jonny quest]

Wobbly, Recluse Torque Drive clutch. You won't even remember Hinson name after you try one.

[bjorn.clauw.1]

https://www.google.be/url?sa=t&sourc...JoAk0M2iu5-Mdg

[jamathi]

That would be a perfect example of history repeating itself. Suzuki used this idea in 1962; they made the third transfer port of their 50 cc works racer as high as the exhaust port, with the intention of pressurizing the crankcase. But in 1963 this third transfer port was no longer any higher than the others...

I think, and always thought, that this was just a mistake made by the draughtsman.
Or a 'joke' from Suzuki, as this is just impossible....maybe to mislead the opposition.....

All 'normal' 2-stroke engines are rev-limited by the blowdown.
When the blowdown becomes insufficient, at high rpm, exhaust gases enter the crankcase.
They usually cause backfiring in the carburettor, sometimes destroying even the inlet valve or reeds.
At Aprilia we could see this very clearly: the transfer passages and crankcase inside became black.

The Ryger, of course, has far insufficient blowdown.
Without it's extremely high crankcase compression it would probably not rev past 10.000rpm.
I really wonder if mixing burned gases with the fresh charge can in any way be positive....
It really can cause auto-ignition of course!
We'll see, the 50cc development will not remain a secret for a long time I suppose!
The spacer under the cylinder looks higher then normal.
Maybe because of a longer connecting rod, which would be good for reliability.....
The people working on it are among the best and most experienced in Holland.
So if they don't make a success of it there really is no hope....

[ken seeber]

Hi Frits

I wanted to know if your generic 2s exhaust design is a good starting point or is it for more modern bike?

Alternatively is there a better starting point for a design ?

Thanks Wallace

I used Frits’s empirical FOS method to design the 3 pipes for the world famous slider engine. Seeing I don’t have EngMod, the FOS method is quick & easy and the slider is just so different, I figured that it’d be shitload better than me throwing darts against the wall.

Just finished adding the convergent cones and tailpipes. Note that it hasn't run with these, but so far they haven’t not worked !!
We based the styling of the tailpipes, fortunately or unfortunately, after some well-known twittering dude.

[katinas]

I think, and always thought, that this was just a mistake made by the draughtsman.
Or a 'joke' from Suzuki, as this is just impossible....maybe to mislead the opposition.....

All 'normal' 2-stroke engines are rev-limited by the blowdown.
When the blowdown becomes insufficient, at high rpm, exhaust gases enter the crankcase.
They usually cause backfiring in the carburettor, sometimes destroying even the inlet valve or reeds.
At Aprilia we could see this very clearly: the transfer passages and crankcase inside became black.

The Ryger, of course, has far insufficient blowdown.
Without it's extremely high crankcase compression it would probably not rev past 10.000rpm.
I really wonder if mixing burned gases with the fresh charge can in any way be positive....
It really can cause auto-ignition of course!
We'll see, the 50cc development will not remain a secret for a long time I suppose!
The spacer under the cylinder looks higher then normal.
Maybe because of a longer connecting rod, which would be good for reliability.....
The people working on it are among the best and most experienced in Holland.
So if they don't make a success of it there really is no hope....

Maybe, on the 50 cc, is a very small difference between the bigger and smaller piston parts, because adequate strength con rod small end, requires relatively more spaces. This is just a guess
With bigger engine ( from 150cc and more) task is simpler, the relative difference between combustion and pumping volume is getting smaller with bigger bore, because of con rod small end dimensions.

[husaberg]

So I finally came upon the idea of using a disc valve on each side, as already had been done by Exactweld.
But I decided to retire, a Dutch friend made some crankcases, but never finished the work.
So I still wonder how it would have gone........

Do you think you would you have had the carbs operating progressively like the Exactweld did Jan?
Also what carb and intake port sizes would you have started with? 2x 30MM?
Pretty sure Flettner could be persuaded to make one to see how it would have gone.
If you give him some basic dimensions. I have some DEA cylinders that could be modified to more closely replicate your originals.