ESE's works engine tuner

[Frits Overmars]

If I remember correctly, the RSA was just like that, with a step in the header. Was the step better on that engine? What was the theory behind the reason for this?

You may have some re-reading to do, Haufen: http://www.kiwibiker.co.nz/forums/sh...post1130876164

[m4r]

Frits, does the Ryger use Meyer's "Knickpleuel"? or even Mederer's "Doppel-Pleuel"?

[Frits Overmars]

Frits, All this current angle area stuff got me thinking. A question on the exhaust vs transfer mixture in-cylinder interface. In the classic and generic current Schnurle scavenging layout, one could imagine that there is a vertical plane, in line with the crankshaft axis, in the centre of the cylinder. One on side of the plane is the downward exhaust flow, the other side seeing the upward scavenging mixture. Yep, I’ll concede this is pretty simplistic.
Disregarding the length of this interface, its width is the bore diameter. Now in a FOS, or other similar concepts, the rising gas flow might consist of a column that is, say, 50% of the bore diameter. This being the case, the perimeter length would equal pi*bore diameter/2, which is over 1.5 times the length of the Schnurle perimeter.
Do you think that this increased perimeter length might result in increased intermixing, hence more fresh mixture lost and more exhaust gas retention, neither good? Not a criticism or trying to give you the shits or anything though.

Obviously, the smaller the contact zone between spent and fresh gases, the better, Ken. But you can't really compare the classic Schnürle-scavenging with either the current 5-transfer systems or with the FOS system, if only because the two Schnürle-transfers would never yield sufficient angle.area for the current rpm-values.
Of course mixing should be avoided which means that the scavenging streams should form a non-turbulent column. In the Schnürle-scavenging this column gets its stability through leaning against the cylinder wall across the exhaust; in current systems much depends on the scavenging balance, which was painstakingly explored by Jan Thiel: every dimension of every port was varied in 0,25 mm steps; it were a lot of combinations...

[Frits Overmars]

Frits, does the Ryger use the Meyer's "Knickpleuel"? or even the Mederer's "Doppel-Pleuel"?

Could you let us know what those are, before I answer that I'm not at liberty to answer?

[m4r]

Could you let us know what those are, before I answer that I'm not at liberty to answer?

something like this

[Frits Overmars]

I was wondering what the specs were on the Derbi. What the crankshaft and the reed valve and tracks looked like. I assume the cylinder and pipe was the same or very similar to the original RSA prototype

I managed to find the comment accompanying the concerning dyno run:

17-12-2004; albero VHM 4034 V4C21;biella Yamaha C21; cuccinetti Rulli Apr C120+viggiu'; pistone Vertex n*149 965 C04; testa DB15 tr. 0.65-0.65 C34; Mappatura G44; candela R7282A-110 gap 0,60mm; accensione microtec M127V2CAN; carb. HRC mod VHM ovale max222; miscela Agip +Elf 3,5%; alimentazione Lam. Daytona

Cylinder, reed valve and pipe were still basically Honda stuff, copied for Derbi by Harald Bartol. I also managed to find a couple of pictures:



Of course there are more pictures, but I haven't got them here.

[wobbly]

Removing the step in the old Honda engine makes its duct a bit like the IAME shown a few pages back.
The duct looses all its velocity well before it approaches the header - exactly the opposite to what is needed, so of course it looses power.
Fill in the spigot shape on any 3 port or T port Honda and power goes up - proven time and time again.

The trend has been to progressively reduce the duct volume, and at Aprilia this was started up at the port by lifting the floor and then filling
in the bottom corner radi, both reducing A port short circuiting as well as increasing blowdown velocity.
Later as Frits has said the exit area was progressively reduced as the floor and roof were machined closer to the center line thus reducing total volume again in the duct.
But we have never seen an Aprilia picture with this late version duct, so also cant tell if the flange entry was modified as well to eliminate the steps.
IF it was done that way then I can guarantee that it made better power.
Honda did this for years on the A Kit and RS250 factory bikes with a nice cast piece that transitioned from the very flattened oval to the round header diameter.

As I have said before, I developed a new T port cylinder that started with a 40 by 35 oval, with steps, and this evolved into a 41 by 32 oval with no steps and the power
increased with both the smaller exit area and the new CNC transition piece.

Then look at a new design like the TM KZ10B, this has a quite small exit area with small steps, modify this by welding the spigot to match the cylinder, then grind the Aux
ducts all the way from big 1/2 moons at the flange face ,tapering smoothly down to nothing at the header and it pics up a couple of Hp at peak,but revs on with something like 6Hp more at 14,000.

[lodgernz]

Attached is the pathetic dyno result for my Honda 50 that I used to think ran really well..
I'd appreciate any ideas as to why the curve is such a strange shape.
The engine is stock except for small Boyesen ports and 2-stage Boyesen reeds.
I wondered if this could be reed flutter. The exhaust is the standard muffler with the guts ripped out.
Apologies for the quality of the screenshot.

[husaberg]

Attached is the pathetic dyno result for my Honda 50 that I used to think ran really well..can anyone suggest what it is.

It looks like Casper.

[jasonu]

It looks like Casper.

Miserable git!

[Yow Ling]

So this Ryger engine , which took a few years to develop, has about 40% MORE HORSEPOWER than the best ever 125cc engine ever produced, the RSA125 by Jan Thiel. It is difficult to belive. Is there going to be a technology transfer sometime soon or a share float. I guess when real evidence is produced we will be stunned, until then I still have faith in Jan Thiel.

[F5 Dave]

I think if it were reed flutter Roger you'd hear it going g.g,g,g,g,ghh and it would plateaux from that point on. My H had a similar curve when running an RG250 pipe. Next pipe changed the curve significantly.

[wobbly]

To have 3 peaks there has to be serious interaction of a couple of elements that are not even remotely matched to make power
in the same bandwidth.
The Boyesens are rubbish anyway so dump them to start with, but i would suspect the pipe is out of sync with the port as well as the ignition curve.

[breezy]

The villiers as well but to be fair the poms needed such long rods because the piston skirts were so long and the piston pins so low.
The cooking MZ's had very long rods as well.



I may have yes, but I am not at liberty to divulge where.

[husaberg]

Sorry it works for Frits.

The cylinder pressure at exhaust opening can be as high as 7 bar, so if you put your transfer reeds even higher up, they must be able to cope with more than 7 bar.
This means strong, heavy reeds that will be very reluctant to open at the very limited scavenging pressure differential that the exhaust suction can generate.
And how would you start the beast? No running = no pipe suction = no starting...
it?

I can't get my head around the very heavy reeds opening bit.
Surely reeds work best as a one way valve.
Maybe its time for Piano hinge reeds.
The trick would be getting them to open when needed. and when the required cylinder pressure differential was reached 4 strokes achieve this all the time with those cams wizwots.