ESE's works engine tuner

[TZ350]

This is what I see........




The port window is 60deg's and the disk cutout is 230deg's 230+60/2=260 deg's duration



Assuming the disk rotates clock wise the port is fast opening and slow closing.



And so my idea of having a fast opening and slow closing valve wasn't so silly after all.............

[kel]

This is what I see........

The port window is 60deg's and the disk cutout is 230deg's 230+60/2=260 deg's duration

...

Its supposedly a lot tamer than that, photo does tell a lot regarding their inlet strategy. I have the RSA time areas also if anyones interested. Wonder who will get the sack when they find out that photos been released.

[TZ350]

Its supposedly a lot tamer than that.

I guess it depends on how they measure the closing point, actual or mean.

I would be very interested in the time areas, and if you have the actual inlet timings I would be very interested in those too.



Mine opens 145 BTDC and starts closing at 75 degrees ATDC and finishes at 85, it runs ok.

I figure I could go more radical, like starts at 85 finishes 95, and it would be interesting to know if opening earlier than 145 BTDC with a pipe thats sucking heavily at BDC would be a good/workable idea.

[koba]

Its supposedly a lot tamer than that, photo does tell a lot regarding their inlet strategy. I have the RSA time areas also if anyones interested. Wonder who will get the sack when they find out that photos been released.

Could be deliberate too, decoy like.

[TZ350]

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Ok here is a picture that gives me some idea of the carb/inlet size needed



41.5mm

[TZ350]

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Aprilia RSA 54 HP.



Well I have a little way to go........

[TZ350]

You guessed right: the 24/7-inlet is named after its 'opening hours'. Originally I wanted to keep the idea a secret until it was fully developed. But I suffer from an ever-increasing lack of time and I would love to see my ideas realised, so I have decided to reveal some of them, like I did with the symmetrical scavenging.

The 24/7-inlet idea arose in 1974 when the rotary inlet disk of my racer stuck open and it just kept running, as long as I kept the engine in the power band. It meant that I rould ride back to the pits instead of pushing through the grass alongside the track side (which I had already done often enough...).
This experience proved what I already knew in theory: that the pumping effect of the crankcase only serves to start the engine; as soon as it runs in the power band, the exhaust pipe takes care of all the gas movement.
So how do you build a rotary disk that stops in the open position when the engine revs reach the power band?
I had no idea...
But then why would you need a rotary disk anyway? Because it flows better than a reed valve? That doesn't matter when you only need it to start the engine. And a reed valve is much simpler to open...

Below you see an old prototype with a typical design error: it is too complicated. You do not need two gear-coupled reeds; one reed that swings out of the way would be enough. And it can be operated by the same servomotor that operates the exhaust power valve



There realy are some interesting ideas on the net...........

Some boys try the idea with their scootor http://www.youtube.com/watch?v=utfzYstegE8 not exactly big rpm but it does show that it would run without a reed valve.

[TZ350]

Cant take everything as gosple but some comments on the net get me thinking.......

"But in practice, if you reduce the distances between crankshaft and crankcase walls to less than 1 mm, the viscous friction of the mixture between the surfaces really costs power at high rpm. And if you make the clearances so tight that lubricating oil can no longer reach the big-end and crankshaft bearings, it will also cost engines.

Another negative aspect: any volume with a narrow 'entrance' between the crankshaft and crankcase surfaces acts as an hydraulic damper on the Helmholtz-resonance in the crankcase.
Aprilia has avoided this by making the space between the crank webs as wide as the big-end bearing. As a result the crankcase volume of the 125 cc RSA engine at TDC is about 650 cc, so the exhaust pipe really has some volume to breathe from.

So much for the fairy tale of high crankcase compression."

[TZ350]

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OK, so some how, I have to get a hole in the side of my GP that looks like this.........

[wobbly]

I think that is the real problem with the side rotary valve - the last pic shows the "ultimate" development of the side port, whereas if you look at the RSA it has an almost identical shape,but turned 90*.
This in effect gives a much narrower port width - the narrower the better, as this means that the blade spends less time actually covering it up ( assuming the same open/close timing), but they have got the area back by making the port very high,with a big valve diameter.

[kel]

[QUOTE=TZ350;1129960944]the crankcase volume of the 125 cc RSA engine at TDC is about 650 cc, so the exhaust pipe really has some volume to breathe from.
QUOTE]

RSA primary compression 1,24:1 (650 cc at TDC; 525 cc at BDC). To increase the volume Aprilia lengthened the rods from 115mm on the RSW to 120mm on the RSA, they raised the cylinder accordingly. Sounds a lot like the bucket approach! Wonder if Jan has stollen anymore of our ideas?
I know we have covered the low compression sucky pipe thing before but its amazing how the old 2 stroke ideas have been turned on their heads

[k14]

RSA primary compression 1,24:1 (650 cc at TDC; 525 cc at BDC). To increase the volume Aprilia lengthened the rods from 115mm on the RSW to 120mm on the RSA, they raised the cylinder accordingly. Sounds a lot like the bucket approach! Wonder if Jan has stollen anymore of our ideas?
I know we have covered the low compression sucky pipe thing before but its amazing how the old 2 stroke ideas have been turned on their heads

How do you know this stuff? I was under the impression it was pretty hush hush and the engines aren't even opened during a GP weekend at the track. If anything goes wrong they put a new engine in and they are rebuilt between GP's back at the Aprillia (or derbi) factory??

Any idea how the injection on the KTM worked?

[kel]

How do you know this stuff?
Any idea how the injection on the KTM worked?

Jan Thiel has retired and the two stroke era is over so the designers dont mind shareing info, all kinds of really good info!
KTM injection well thats a strange one even though their GP two stroke program is long gone that still dont talk or release photos (press releases aside). But yes I do know how it works, supplementary injection that feds into the crankcase to richen the mixture, just another approach to a power jet.

[wobbly]

The KTM injection was Bartols way of preventing the engines from siezing on the overev during downchanges.
Pulling 15000 + with no air, and thus fuel, and thus oil, wreaked havoc with some riders, the injector squirted fuel/oil into the case when this was occurring.

[k14]

The KTM injection was Bartols way of preventing the engines from siezing on the overev during downchanges.
Pulling 15000 + with no air, and thus fuel, and thus oil, wreaked havoc with some riders, the injector squirted fuel/oil into the case when this was occurring.

Ok, that makes sense. I read an interview with Bartol about the KTM once and the way he talked about it made it sound like it was the best invention ever. So what changes did Aprilia do from the RSW to RSA to be able to make the jump ahead of KTM quite easily?