[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 2) (Locked)

Honda cylinders have an oval exhaust duct!

Yes, oval port but not as rectangle as the RSA – do you think they would benefit from the RSA shape?

I really do not know.
It could be tried, only after trying you can know!
But of course their exhaust port shape is a lot different.
Of course we also tried the 'Honda' exhaust shape.
It gave less power than ours, but carburation was a bit easier.
About 1,5Hp less.

Thank you Jan.
1973 - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 2) (Locked) - Page 6 101130

The sizes are 39.5 width x 27.5 height (without the radius).
Now I can imagine your next request 1973 - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 2) (Locked) - Page 6 727249

1973 - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 2) (Locked) - Page 6 727249

The opening time is 196 ° measured without taking into account the radius.

Edit by Damien (Francis's son...), Maybe you were talking about this dimensions ? 1973 - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 2) (Locked) - Page 6 55116

1973 - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 2) (Locked) - Page 6 55116

:

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Right Damian, sorry,I just missed a little word. 1973 - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 2) (Locked) - Page 6 165226

1973 - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 2) (Locked) - Page 6 165226

GtG001 a écrit:: Will you tell us the final width and height of the RSA exhaust exit ?

Now you have all the informations entry and exit. 1973 - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 2) (Locked) - Page 6 998726

1973 - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 2) (Locked) - Page 6 998726

Nombre de messages : 55 Localisation : Allemagne Date d'inscription : 23/12/2011

Jan, did you ever compare the routing of the RSW and RSA exhaust pipes? I am wondering if the outcome would have been different with the almost straight routing of the RSW exhaust compared to the routing of the RSA exhaust pipe (same pipe dimensions on both).

Thank you Jan, Francis and Damian for the information.

Congratulations Francis and Damian (FPE) on your great results in the CIK Superkart World Title recently with your new motor. 1973 - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 2) (Locked) - Page 6 921866

1973 - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 2) (Locked) - Page 6 921866

Thank you Jan and Frits as your gift of information keeps bearing fruit for others too. 1973 - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 2) (Locked) - Page 6 241515

1973 - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 2) (Locked) - Page 6 241515

1973 - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 2) (Locked) - Page 6 771973

Best regards
Allan.

Haufen a écrit:: Jan, did you ever compare the routing of the RSW and RSA exhaust pipes? I am wondering if the outcome would have been different with the almost straight routing of the RSW exhaust compared to the routing of the RSA exhaust pipe (same pipe dimensions on both).

I think the bend in the RSA exhaust lost us some power.
And also the necessary longer tailpipe seemed to cause some detonation.
If I had to make a new engine today I would certainly NOT make another RSA!
And it would have a straight exhaust.

Hi Jan,
How much HP do you think it cost making the pipe for the RSA (bent) compared to the straight one. Could it have been compensated in dimensions for the bend or was it a direct loss?

Thanks,
Allan.

I estimate about 0,5 HP.
The bend was negative, as well as the longer tailpipe.

Nombre de messages : 37 Localisation : Hellas Date d'inscription : 08/02/2012

Jan Thiel a écrit:: ...................
If I had to make a new engine today I would certainly NOT make another RSA!
And it would have a straight exhaust..............

So what path would you take,generaly?two rotary?
belt primary drive as mentioned before?Am i asking too much? Very Happy

Definitely two rotary but no belt drive.

XpTpSMTT a écrit:: So what path would you take,generaly? two rotary?

Jan Thiel a écrit:: Definitely two rotary but no belt drive.

Is it I missed something somewhere? Two rotary, one on each side?

Nombre de messages : 37 Localisation : Hellas Date d'inscription : 08/02/2012

fpayart a écrit:

XpTpSMTT a écrit:: So what path would you take,generaly? two rotary?

Jan Thiel a écrit:: Definitely two rotary but no belt drive.

Is it I missed something somewhere? Two rotary, one on each side?

Υes.why not? you could-on a single cylinder-
have a straight shooting pipe towards the rear with the good wheight distribution
of the rsw engine.
Of course there would be a long way to go.
What would happen with the mixtures colliding in the center on the con rod?
And many more like the rotating crankshaft etc.
But then wouldn't you also try direct injection?
Or maybe infinately variable valve area-get rid of the carbs?
Or maybe this coffee is too strong...

Nombre de messages : 55 Localisation : Allemagne Date d'inscription : 23/12/2011

Jan Thiel a écrit:: Definitely two rotary but no belt drive.

Wouldn't a single front Disc be nice also? With the carb facing forward? Or would there be not enough space? The airbox and maybe some isolating material would isolate the carb from the radiator heat.

Nombre de messages : 37 Localisation : Hellas Date d'inscription : 08/02/2012

Haufen a écrit:

Jan Thiel a écrit:: Definitely two rotary but no belt drive.

Wouldn't a single front Disc be nice also? With the carb facing forward? Or would there be not enough space? The airbox and maybe some isolating material would isolate the carb from the radiator heat.

Your answers are in part one around page 30 i think.

Haufen a écrit:

Jan Thiel a écrit:: Definitely two rotary but no belt drive.

Wouldn't a single front Disc be nice also? With the carb facing forward? Or would there be not enough space? The airbox and maybe some isolating material would isolate the carb from the radiator heat.

To do this succesfully the crankshaft would have to turn backwards.
And there is insufficient space for the airbox!

To success all these "mods" to find space behind the cooler, what you think if you put the havier gear box in front of the crankshaft , you have to add an axle to compensate the counterrunning, at low position (thanks the space left by the straight exhaust) and put the drive sprocket to is optimal positionning...

Adding an axle for counterrunning would cost you about 5% power.
For a 125 that means you lose about 2,7HP.
Do you still like it?

Could you have a rear facing exhaust port with the rotary inlet still on the rear of the motor and keep the forward rotation?

Nombre de messages : 55 Localisation : Allemagne Date d'inscription : 23/12/2011

Or you could have the cylinder pointing downwards.

Like those ones ?

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1973 - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 2) (Locked) - Page 6 1993206895

1973 - [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 2) (Locked) - Page 6 1993206895

Nombre de messages : 55 Localisation : Allemagne Date d'inscription : 23/12/2011

fpayart a écrit:: Like those ones ?

Exactly :) Maybe even a bit more to allow for the best compromise between an exhaust pipe as straight as possible and (no) plug fouling (if the engine should prove to be prone to).

Howard Gifford a écrit:: Could you have a rear facing exhaust port with the rotary inlet still on the rear of the motor and keep the forward rotation?

I do not think so.

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