[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5)

Nombre de messages : 86 Localisation : Australia Date d'inscription : 05/05/2012

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Frits if you would be so kind to help me understand please
Exhaust duration of 196* with a sharp edged exhaust duct ceiling
I then added the 5% of stroke radius to the exhaust duct ceiling with the 15* offset
I am not able to attain the 202* exhaust duration as described, I assume I have gotten something wrong & or miss understood my previous readings

Dernière édition par Frits Overmars le Sam 7 Sep 2019 - 16:11, édité 1 fois

RAW a écrit:: Frits if you would be so kind to help me understand please.
Exhaust duration of 196* with a sharp edged exhaust duct ceiling. I then added the 5% of stroke radius to the exhaust duct ceiling with the 15* offset.
I am not able to attain the 202* exhaust duration as described, I assume I have gotten something wrong & or miss understood my previous readings

There are one or two factors that may be causing differences here, RAW.
1: The exhaust top edge radius on the Aprilia racers tended to deviate a little from the 5 % of the stroke that I use as a guideline, and the 15° offset was not always all that exact either.
2: Did you take the 25° downward angle of the exhaust duct roof into account?
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Nombre de messages : 86 Localisation : Australia Date d'inscription : 05/05/2012

Frits thank you, I have a very annoying laptop that consistently shuts itself down & or won’t turn on therefore I have been unable to complete any cad reworks thus far.
The 25* you described I definitely have gotten incorrect with the duct ceiling being almost 65* from the bore as per your picture
Another area of port duration differences that may have thrown my cylinder deck face down to port ceiling dimensions is with regards to the RSW cylinder heads 54mm diameter / 190mm squish Radius being approximately 0.25mm further away from the cylinder top than the RSA cylinder top / deck.
Given I’m up shit creek without a paddle given my laptop failure I wondered if you would post the port ceiling & floor dimensions from BDC or TDC for me ?
Thanks in advance

RAW a écrit:: The 25* you described I definitely have gotten incorrect with the duct ceiling being almost 65* from the bore as per your picture... I wondered if you would post the port ceiling & floor dimensions from BDC or TDC for me ?

You will have noticed that the 25° and 65° values were swapped in the above drawing; it's been corrected now.
That drawing already contains the port ceiling dimensions. I can't recall the port floor dimensions off hand, as Jan Thiel experimented with various values. I think the production cylinders had 3 or 5 mm, but other versions may have been released as well; hopefully Jan will chime in.

Nombre de messages : 86 Localisation : Australia Date d'inscription : 05/05/2012

Thanks again,, I was asking for the dimensions for all 5 port windows due to my computer issues, I had drawn the degrees durations for all 5 RSA ducts, I can not get this dam laptop to turn on now.
I suppose that’s what happens when you spill a cuppa on the keyboard. I paid a small fortune to have it repaired, I don’t think they did a good job at all

No wonder I prefer mechanical items

RAW a écrit:: I was asking for the dimensions for all 5 port windows

No problem. The A-ports are 130° = 13,16 mm above BDC. The B-ports and the C-port are 132° = 13,56 mm above BDC.

Nombre de messages : 86 Localisation : Australia Date d'inscription : 05/05/2012

Frits thank you,
I do have another query if you would care to assist ?
I have done some calculations based from a Facebook post from Luc regarding the
RSA cylinder port Arc lengths in mm
C = 15, B = 26, A = 26.6, Sub exh = 22.7, Main exh = 42.1
Bore Circumference 169.65
Transfer ports combined = 120.2, remaining arc lengths = 49.45,
Transfer port bridges thickness assumption = Qty 4 x 1.5mm = 6, ( 49.45 _ 6 = 43.45 )
What does not make any sense to me is the photograph shows the A ports extend beyond the Main exh port vertical plain however the dimensions do not concur this. [Vous devez être inscrit et connecté pour voir cette image]

RAW, I will not have anything to do with that person.

Nombre de messages : 86 Localisation : Australia Date d'inscription : 05/05/2012

Haha, the numbers pretty much explain that, I’ve seen enough RSA stuff over the years to know it incorrect.
Would you care to clear theory with fact ?

No thanks. I'd rather keep this forum civilized.

Nombre de messages : 86 Localisation : Australia Date d'inscription : 05/05/2012

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Based upon dimensions I remember from something I had previously read.

Nombre de messages : 102 Localisation : Biblis Date d'inscription : 14/01/2017

@ Francis,

the parts for the electric powerjet valve body are nearly finished. Now i have to set the stroke for the solenoid.
How many milimeters does your valve needle travel until it sits upon the difusor?
I am shortening the "solenoid-piston" to reach the desired measure.
I thought of 2,0mm from Open to completely Shut.
Best regards,
Bernd

Hi Bernd,

The least possible, 0.5mm is enough. But watch out for rubber compression, add 0.1mm

Nombre de messages : 102 Localisation : Biblis Date d'inscription : 14/01/2017

Hi Francis,

thanks for the info!
My solenoid got a maximum stroke of 4,2mm and is a pusher-type.
When i adjust the currentless position 0,6mm before shut the stroke will be more than enought.
Best regards,
Bernd

Dernière édition par LucF le Mer 18 Sep 2019 - 15:54, édité 1 fois

RAW a écrit:: [Vous devez être inscrit et connecté pour voir cette image]

Based upon dimensions I remember from something I had previously read.

RAW, it's a newer version Jan wrote on FB.

Nombre de messages : 351 Localisation : Belgique Date d'inscription : 05/12/2011

et voila, c'est règler et La Belgique a sa revanche pour la coupe du monde 2018, parce que ce WE, nous avons gagner notre catégorie au 10h de Mob à Laon aprilia - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 32 921866

aprilia - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 32 921866

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Bravo !

Nombre de messages : 102 Localisation : Biblis Date d'inscription : 14/01/2017

Hallo,
anyone knows where to buy a Aprilia RSW/RSA 250 fairing?
I found only Motoforza.
Best regards,
Bernd

Scavening directions program, derivide from Aprilia RSA.

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Nombre de messages : 351 Localisation : Belgique Date d'inscription : 05/12/2011

I've searched but couldn't find it Frits :

for calculating the minimum safe vertical half axis, do you use the actual port width from the portmap, or the chordal port width ?
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JanBros a écrit:: I've searched but couldn't find it Frits:
for calculating the minimum safe vertical half axis, do you use the actual port width from the portmap, or the chordal port width ?

I use chordal widths. Portmaps are impractical and not sufficiently accurate. They may be suitable for showing the number of ports in a cylinder, but not the port dimensions Wink

.

Nombre de messages : 351 Localisation : Belgique Date d'inscription : 05/12/2011

tnx.

so if I read your answer correctly, you always talk about chordal when you mention port width's and we should never bother you again with that question ? aprilia - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 32 809262

aprilia - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 32 809262

Nombre de messages : 102 Localisation : Biblis Date d'inscription : 14/01/2017

Hi Frits,

i`ve got a question about an exhaust drawing you posted back in time.
As I´m going to build a system for my PVP-bike i compared the kart exhaust to the Aprilia one and notices slight differences.
I got these adaptors to slide over the socket srewed to the cylinder.
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Here your exhaust:
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Kart: I use this drawing on my Rotax 256 with the old PVP cylinders, good top end power, but quite agressive.
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On your drawing: Can you tell me what is the starting point to weld on the adaptor? I guess the first 63mm section is the duct. But the next 40mm section, is that the socket or yet part of the pipe?

Best regards,
Bernd

Döllinger a écrit:: Hi Frits, I've got a question about an exhaust drawing you posted back in time.... Can you tell me what is the starting point to weld on the adaptor? I guess the first 63mm section is the duct. But the next 40mm section, is that the socket or yet part of the pipe?

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The 40 mm is the flange that is bolted to the cylinder. But that does not really matter; the only important thing is that the exhaust gases 'see' the internal dimensions of the exhaust system.

Citation :: As I´m going to build a system for my PVP-bike i compared the kart exhaust to the Aprilia one and notices slight differences.I use this drawing on my Rotax 256 with the old PVP cylinders, good top end power, but quite agressive.

I assume that you compared your PVP pipe to the Aprilia Tubo-102. But there have been many Aprilia pipes before the '102'.
Below are the three pipes that proved to be the best during those years.
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Now compare this:
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Nombre de messages : 102 Localisation : Biblis Date d'inscription : 14/01/2017

Hallo Frits,

thank you for you profund answer. The last shown pipes are quite the same. The first PVP-cone is just a bit longer/flatter. Looks like he got an eye on your drawing.

Regarding the electric powervalve:

Yesterday i got the modified carburetors. As the motor is mounted with a tilt of 15° and the carburetors got a shape i just asked for a 15° modification. No problem.

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I want to install the uptake with the jet completely vertical like this. Nowhere else is space for it.
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Then i seal up one side of the mirrored fuel intake with 2 bushings and lead the fuel out that way.
The black circle is the planned position for the valve unit.

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@ Frits or Francis. Is there a maximum distance between the slide surface and the middle of the difusor? In my case i would estimate 8-9mm. Can there be a problem
with weakening undertow? Is it ok to solve this by giving an angle to the difusor, towards the intake direction instead of a radial 90° angle?
Best regards,
Bernd

» [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5)
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