AccueilGalerieRechercherDernières imagesS'enregistrerConnexionNouveaux messages depuis dernière visite
Rechercher
 
 

Résultats par :
 
Rechercher Recherche avancée
Qui est en ligne ?
Il y a en tout 50 utilisateurs en ligne :: 1 Enregistré, 0 Invisible et 49 Invités :: 3 Moteurs de recherche

petitpierre

Le record du nombre d'utilisateurs en ligne est de 508 le Sam Mar 09 2024, 18:15
Derniers sujets
»  [MotoGP] Infos , nouveautés , potins , tests et plus pour la saison GP 2025 ...
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeHier à 21:05 par bartau

»  [MotoGP] GP 2024 du Qatar à Losail les 8 - 9 et 10 Mars 2024
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeHier à 20:10 par damelydie

» André Luc Appietto
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeHier à 19:05 par FB21

» [Oldies] Quizz (29)
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeHier à 15:27 par supermono

» [Endurance] Saison 2024 .
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeHier à 14:24 par yves kerlo

» [Technique] Vous avez dit "Distribution"?
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeHier à 12:00 par jack177071

» [Oldies] Angel Nieto Mike Hailwood (part 6)
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeHier à 10:32 par Apriliabarth

» [Oldies] Jack Findlay, pilote de légende
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeHier à 00:45 par jack177071

» [Oldies] Gérald Motos
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeDim Mar 17 2024, 11:45 par collecto

» GP Canada Mosport 29 & 30 septembre 1967
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeDim Mar 17 2024, 09:13 par Adco

» [Technique] Bielle de Formule 1 tout à fait passionnante
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeDim Mar 17 2024, 09:13 par Dan42

» Demande d'aide pour moteur 3 cylindres
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeSam Mar 16 2024, 17:20 par Joel Enndewell 2424

»  [SORTIES] Sunday Ride Classic 2024 .
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeSam Mar 16 2024, 12:25 par Joel Enndewell 2424

»  [WSBK] Infos 2024 .
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeSam Mar 16 2024, 11:33 par EDOUARD Jean

» Antony et le voisinage il y a 50 ans…
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeSam Mar 16 2024, 08:55 par FB21

» [Moteurs] Question Honda 1000 CBX
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeSam Mar 16 2024, 07:36 par manx

» Drole de carbu
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeVen Mar 15 2024, 12:51 par Charly

» controle technique moto
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeJeu Mar 14 2024, 23:37 par Ninja Atak

» Salon du 2 roues à Lyon 7,8,9 et 10 mars
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeJeu Mar 14 2024, 21:23 par Ed

» [Oldies] Yves Le Toumelin
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeJeu Mar 14 2024, 13:06 par SLT

» [Oldies] Motocistes d'époque
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeMer Mar 13 2024, 19:46 par Dialmax

» Anniversaire de nos pilotes de GP.
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeMer Mar 13 2024, 13:41 par DidierF

» [Technique] Redressage de tube de fourche
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeMer Mar 13 2024, 12:31 par Joel Enndewell 2424

» Musée Follis
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeMer Mar 13 2024, 12:20 par Dialmax

» Le moteur rotatif de Wankel : espoirs et désillusions.
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeMer Mar 13 2024, 10:36 par Frits Overmars

» Histoire de MANX
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeMar Mar 12 2024, 08:58 par Dan42

» [Technique] Distribution variable
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeDim Mar 10 2024, 11:33 par Adco

» [Oldies] Angel Nieto Mike Hailwood (part 7)
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeDim Mar 10 2024, 10:32 par jack177071

» (Oldies) Salon Rétromobile 2024
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeSam Mar 09 2024, 11:59 par jeannin

» [Oldies] Restauration de mon side-car des années 70, la suite!
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeVen Mar 08 2024, 13:01 par Joel Enndewell 2424

Mots-clés
bresse side artisanales motos zone motobecane 1976 Mans ROAD oldies aprilia coupe classic RACING yamaha ducati moto suzuki 1973 inventaire wanted rouge charade francaises bourg 2013
Meilleurs posteurs
Marc
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Voting16[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Voting13[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Voting15 
EDOUARD Jean
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Voting16[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Voting13[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Voting15 
philwood
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Voting16[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Voting13[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Voting15 
Pierre"PhilRead"
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Voting16[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Voting13[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Voting15 
mickey
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Voting16[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Voting13[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Voting15 
yves kerlo
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Voting16[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Voting13[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Voting15 
bubu
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Voting16[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Voting13[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Voting15 
Fügner
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Voting16[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Voting13[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Voting15 
Dialmax
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Voting16[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Voting13[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Voting15 
Jarno
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Voting16[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Voting13[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Voting15 
La réclame...
-23%
Le deal à ne pas rater :
EVGA SuperNOVA 650 G6 – Alimentation PC 100% modulaire 650W, 80+ ...
77.91 € 100.91 €
Voir le deal

 

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

Aller en bas 
+62
Arcigno
Frank S.
Oliver Oettel
chiccopeso
BlackD3vil
atte roskam
Panas
Kato74
I.T-Racing
cassandre
crigar
walms
dga
vorlis
SaltRacer
jack177071
Architito2002
yeahhim
Howard Gifford
2strokeman
remix31
Apriliabarth
Tim Ey
pojoran
Institute of TwoStrokes
Eric_91
jfn2
melvyn trevor
JPG
Toop
alain combemale
Charles Kaneb
carlovitch1
JanBros
Frits Overmars
MINGRET01
EDOUARD Jean
Maurice Specken
samy
laranjateam
polcat88
motori49
Quod et probat
Elmi
bentou
LeonardoMRF2
MANETON
RAW
Vannik
desmofr16
Döllinger
fullgazlolo
Emmanuel Laurentz
SLT
Dan42
Adco
Marc
CARBONX2
porttiming124
fpayart
Jan Thiel
peter1962
66 participants
Aller à la page : Précédent  1 ... 5 ... 7, 8, 9 ... 13 ... 19  Suivant
AuteurMessage
Frits Overmars

Frits Overmars


Nombre de messages : 2610
Age : 75
Localisation : Raalte, Holland
Date d'inscription : 12/10/2010

[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Empty
MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5)   [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeJeu Juil 29 2021, 19:24

Eric_91 a écrit:
With Narrower exhaust duct im expect less gas expansion so higher exhaust temp so more Max Power but less bottom end, correct?
A narrower exhaust duct will provoke less turbulence, hence more remaining energy in the exhaust gas; in this respect you may be right. But I also expect a different, stronger effect: the narrower duct will lower the Helmholtz frequency of the exhaust system, so more bottom end. Try and let us know, Eric.
Revenir en haut Aller en bas
carlovitch1




Nombre de messages : 1028
Age : 57
Localisation : Pays Catalan
Date d'inscription : 20/05/2018

[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Empty
MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5)   [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeVen Juil 30 2021, 15:55

Good afternoon everyone, I have another question for Frits or Jan.
I've seen in a magazine a strange mod applied to the dome of a head, see these grooves:
[Vous devez être inscrit et connecté pour voir cette image]

The tuner claims it improves atomization of the fuel, then most likely its combustion, and prevents from detonation.
What is your opinion on such thing?
Revenir en haut Aller en bas
fullgazlolo




Nombre de messages : 1832
Localisation : GE-CH
Date d'inscription : 04/01/2016

[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Empty
MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5)   [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeVen Juil 30 2021, 16:18

Ce serait pas une culasse lagarigue... inventeur aussi du piston gonflable?
Revenir en haut Aller en bas
Frits Overmars

Frits Overmars


Nombre de messages : 2610
Age : 75
Localisation : Raalte, Holland
Date d'inscription : 12/10/2010

[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Empty
MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5)   [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeVen Juil 30 2021, 16:55

carlovitch1 a écrit:
I've seen in a magazine a strange mod applied to the dome of a head, see these grooves:
The tuner claims it improves atomization of the fuel, then most likely its combustion, and prevents from detonation. What is your opinion on such thing?
It is 100% Bullshit, just like internal golf ball-dimpling and turbo-crankshafts.
I have seen a power comparison of such a cylinder head, before and after the modification.
The after-version was fractionally better but the tuner 'forgot' to mention that he had also raised the compression ratio.
A cylinder head with the raised compression ratio and without the grooves would have been a lot cheaper and perform a lot better, but the tuner was not going to say that to his customers...
Revenir en haut Aller en bas
carlovitch1




Nombre de messages : 1028
Age : 57
Localisation : Pays Catalan
Date d'inscription : 20/05/2018

[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Empty
MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5)   [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeVen Juil 30 2021, 17:26

Thanks for your reply, Frits !
Revenir en haut Aller en bas
Institute of TwoStrokes




Nombre de messages : 149
Localisation : Australie
Date d'inscription : 15/10/2010

[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Empty
MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5)   [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeJeu Aoû 12 2021, 08:27

carlovitch1 a écrit:
Good afternoon everyone, I have another question for Frits or Jan.
I've seen in a magazine a strange mod applied to the dome of a head, see these grooves:
[Vous devez être inscrit et connecté pour voir cette image]

The tuner claims it improves atomization of the fuel, then most likely its combustion, and prevents from detonation.
What is your opinion on such thing?
Big jump in the impression ratio along with a corresponding decrease in you bank balance
Revenir en haut Aller en bas
Döllinger




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

[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Empty
MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5)   [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeSam Sep 18 2021, 00:14

One question about exhaust for Frits.

What inside diameter had the tailpipes of the RSW 125/250?

With the FOS formula for the tailpipe i calculate an inside diameter of approx 29-29,4mm depending of the assumed rpm of max. power. That sounds quite big.
On the drawing of the "tubo 102" the restrictor is labeled 23,3mm. Jan Thiel wrote here in the forum that the RSA had a tailpipe inside diameter of 26mm.
There´s a big difference between 26mm and 29,4mm.

As I´m about to construct a pair of exhaust with the "tubo 102"-design I´m really interested in your suggestion about the "right" tailpipe diameter.
The max power rpm of the engine is about 12.800-13.000 rpm and the cylinder capacity is 124,9ccm.
Thank you in advance for an answer.
Best regards,
Bernd
Revenir en haut Aller en bas
Frits Overmars

Frits Overmars


Nombre de messages : 2610
Age : 75
Localisation : Raalte, Holland
Date d'inscription : 12/10/2010

[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Empty
MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5)   [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeSam Sep 18 2021, 11:19

Döllinger a écrit:
With the FOS formula for the tailpipe i calculate an inside diameter of approx 29-29,4mm depending of the assumed rpm of max. power. That sounds quite big. On the drawing of the "tubo 102" the restrictor is labeled 23,3mm. Jan Thiel wrote here in the forum that the RSA had a tailpipe inside diameter of 26mm. There´s a big difference between 26mm and 29,4mm.
The flow difference between a 26 mm tube and a 29,4 mm tube would be huge, but the 23,3 mm restrictor (diameter D5 in the drawing below) at the entrance of this tube should annihilate any flow difference. And in order to make sure that the restrictor,
and not the tube diameter D6 downstream of the restrictor is decisive, I advised a D6 diameter that is markedly bigger than D5.

The difference between perforated silencer tubes with 26 mm or 29,4 mm diameter is not big when it comes to silencing,
but in my experience the bigger diameter, with obviously a bigger wall surface area, gives slightly better silencing.
[Vous devez être inscrit et connecté pour voir cette image]
Revenir en haut Aller en bas
melvyn trevor




Nombre de messages : 21
Localisation : england
Date d'inscription : 31/05/2012

[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Empty
MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5)   [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeLun Oct 11 2021, 14:48

Hi Frits,
I am puzzling over what happens in the rear cone, or reflector, of a typical race exhaust pipe. Would I be correct in imagining that the reducing cone forms a pressure gradient with the diameter adjacent the pipe middle diameter at the lowest and the highest pressure at the tailpipe junction. Is the tailpipe entry point also at the highest temperature in the length of the rear cone? My real question concerns the behavior of reflected waves, can waves from the tailpipe area travel faster and have a larger amplitude than those from the larger diameter and can they overtake and collide with the slower waves and, what are the possible consequences of that collision?
A lot of questions I know but any explanation you can offer is gratefully received, I am also sure there must be many readers just as in the dark about these things as I am, and rear cones don`t seem to get the same analysis as other parts of an exhaust pipe. Many thanks in advance.
Cheers, Melvyn.
Revenir en haut Aller en bas
Frits Overmars

Frits Overmars


Nombre de messages : 2610
Age : 75
Localisation : Raalte, Holland
Date d'inscription : 12/10/2010

[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Empty
MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5)   [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeLun Oct 11 2021, 16:30

melvyn trevor a écrit:
Hi Frits,
            I am puzzling over what happens in the rear cone, or reflector, of a typical race exhaust pipe. Would I be correct in imagining that the reducing cone forms a pressure gradient with the diameter adjacent the pipe middle diameter at the lowest and the highest pressure at the tailpipe junction. Is the tailpipe entry point also at the highest temperature in the length of the rear cone? My real question concerns the behavior of reflected waves, can waves from the tailpipe area travel faster and have a larger amplitude than those from the larger diameter and can they overtake and collide with the slower waves and, what are the possible consequences of that collision?
A lot of questions I know but any explanation you can offer is gratefully received, I am also sure there must be many readers just as in the dark about these things as I am, and rear cones don`t seem to get the same analysis as other parts of an exhaust pipe. Many thanks in advance.
Cheers, Melvyn.
Hi Melvyn, the answers to your questions are yes, yes, yes, yes, yes, yes  Wink . But I feel that your 'real' question deserves a more elaborate reaction than just six yesses.
Waves with a large amplitude can overtake waves with lower amplitudes and velocities that were generated earlier in time. If that happens, they join forces and start moving even faster.

A typical wave has more or less a sine shape, starting with a modest amplitude that becomes stronger and stronger as the wave develops towards its maximum amplitude.
The initial part of the wave moves rather slow and it gets overtaken by the subsequent stronger parts. Because of this overtaking, the resultant wave not only becomes stronger but also shorter and steeper. If the wave is underway long enough, it can develop into a very short but vicious shock wave. But shock waves are not good at moving a mass of gas, so they are of no use in an engine.

This is the reason that the shape of the reflector cone in an exhaust pipe is fairly defined. If you make it too steep, the strong reflected wave will develop into a shock wave before it arrives back at the cylinder, and it will do a rather poor job at pushing washed-through fresh mixture back into the cylinder.

Now if a strong wave can overtake a weak wave, what happens when that weak wave is a suction wave?
Suction waves move really slow compared to pressure waves, so there is a real risk that they will be overtaken. And when that happens, they do not join forces. On the contrary, they kill each other.

To give a numerical impression: the speed of sound in ambient air is a little over 300 meters per second.
Strong pressure waves in hot exhaust gas can double that. But suction waves, especially if they have a strong negative amplitude, can be as slow as 200 meters per second.

In a typical two-stroke exhaust pipe we see a header that may be either parallel or very slightly conical, then a diffuser, consisting of one or more cones, then a parallel belly, and finally a reflector, again consisting of one or more cones.
The diffuser sends a suction wave back to the cylinder. A bit later on, the reflector sends a pressure wave back to the cylinder.
If the pressure wave overtakes the suction wave, neither of them will survive. This is where the belly comes in: it creates a battle-free period of time between the two.

Above we mentioned the header. Why doesn't it have a larger angle of aperture, so it can do a better suction job?
Because that would be a waste of exhaust gas energy.
When the exhaust port starts opening, the pressure differential between the combustion gases in the cylinder and the pressure in the exhaust system is supercritical. Those combustion gases will leave the cylinder with a flow velocity of Mach 1 and extra sucking at the low-pressure end of the header cannot raise the flow velocity any further.

Besides, as long as the flow velocity in the header is so high, a suction wave would not be able to move upstream through the header towards the cylinder anyway. It would be like a bird trying to fly into a storm: it does not advance but only wears itself out. So it's better to wait for the pressure in the cylinder and the flow velocity in the header to drop somewhat before we let the diffuser start sucking.


Dernière édition par Frits Overmars le Mar Oct 12 2021, 14:00, édité 1 fois
Revenir en haut Aller en bas
melvyn trevor




Nombre de messages : 21
Localisation : england
Date d'inscription : 31/05/2012

[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Empty
MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5)   [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeLun Oct 11 2021, 18:42

Fantastic, that`s great Frits, a very comprehensive and expansive reply, far more an authoritative answer than can be found in a dozen of the "popular" tuning books. Thank you so much.
Regards, Melvyn
Revenir en haut Aller en bas
pojoran




Nombre de messages : 4
Localisation : Thailand
Date d'inscription : 11/09/2021

[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Empty
MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5)   [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeMer Oct 13 2021, 11:34

Hi Frits.
Would you please advise me about crank shaft balance rate effect to power? or purpose vibration reduce only?
What 's concept of crank shaft balnce & RSA use balance rate ratio 50%?
What 's balance rate different in term of power or anything between 40%,50%,60%
Thank you for your advice.
Regards. Poj
Revenir en haut Aller en bas
Frits Overmars

Frits Overmars


Nombre de messages : 2610
Age : 75
Localisation : Raalte, Holland
Date d'inscription : 12/10/2010

[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Empty
MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5)   [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeMer Oct 13 2021, 11:51

pojoran a écrit:
Hi Frits.
Would you please advise me about crank shaft balance rate effect to power? or purpose vibration reduce only?
What 's concept of crank shaft balnce & RSA use balance rate ratio 50%?
What 's balance rate different in term of power or anything between 40%,50%,60%.
There is no direct coherence between crankshaft balance rate and engine power, but vibrations may strongly effect the carburation and thus the power, so applying a balance shaft may give a net power profit. Reducing vibrations may also allow for a lighter frame construction.
When using a balance shaft, it is advisable to give both the crankshaft and the balance shaft balance factors of 50%.
Revenir en haut Aller en bas
MINGRET01

MINGRET01


Nombre de messages : 24
Localisation : lyon
Date d'inscription : 19/11/2011

[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Empty
MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5)   [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeJeu Oct 14 2021, 22:06

Hello Frits,

what is timing value to openning and closed rotary valve to 125 RSA?

Thank
Revenir en haut Aller en bas
carlovitch1




Nombre de messages : 1028
Age : 57
Localisation : Pays Catalan
Date d'inscription : 20/05/2018

[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Empty
MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5)   [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeVen Oct 15 2021, 08:34

I think you have the answer already in this page (page 19 of the topic): [Vous devez être inscrit et connecté pour voir ce lien]

Revenir en haut Aller en bas
MINGRET01

MINGRET01


Nombre de messages : 24
Localisation : lyon
Date d'inscription : 19/11/2011

[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Empty
MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5)   [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeVen Oct 15 2021, 10:06

I have seen this topic, but is not really clear.
Revenir en haut Aller en bas
carlovitch1




Nombre de messages : 1028
Age : 57
Localisation : Pays Catalan
Date d'inscription : 20/05/2018

[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Empty
MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5)   [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeVen Oct 15 2021, 10:57

Isn't 146°/93° (before/after TDC) not clear enough?
Revenir en haut Aller en bas
Tim Ey




Nombre de messages : 20
Localisation : Allemagne
Date d'inscription : 22/05/2013

[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Empty
MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5)   [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeSam Oct 23 2021, 09:44

Hi everyone,

i am searching for more pictures of a 1991 Aprilia AF1 250cc racebike. This is the only picture I was able to find of it online.
[Vous devez être inscrit et connecté pour voir ce lien]
It states, that it is a 1991 used in Modena.

Anyone got more pictures of the whole design?

Regards
Tim
Revenir en haut Aller en bas
Frits Overmars

Frits Overmars


Nombre de messages : 2610
Age : 75
Localisation : Raalte, Holland
Date d'inscription : 12/10/2010

[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Empty
MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5)   [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeMar Oct 26 2021, 15:43

Tim Ey a écrit:
i am searching for more pictures of a 1991 Aprilia AF1 250cc racebike. This is the only picture I was able to find of it online.
[Vous devez être inscrit et connecté pour voir ce lien]
It states, that it is a 1991 used in Modena. Anyone got more pictures of the whole design?
Here you go Tim.
[Vous devez être inscrit et connecté pour voir cette image]
Revenir en haut Aller en bas
Tim Ey




Nombre de messages : 20
Localisation : Allemagne
Date d'inscription : 22/05/2013

[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Empty
MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5)   [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeMar Oct 26 2021, 16:04

Bedankt Frits,
but that is not the design I mean.

I linked this one
[Vous devez être inscrit et connecté pour voir cette image]

Regards
Tim
Revenir en haut Aller en bas
carlovitch1




Nombre de messages : 1028
Age : 57
Localisation : Pays Catalan
Date d'inscription : 20/05/2018

[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Empty
MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5)   [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeMar Oct 26 2021, 17:56

Isn't it the same bike but with different colours? Or you would like to see the complete graphics of the bike?

[Vous devez être inscrit et connecté pour voir cette image]
Revenir en haut Aller en bas
Apriliabarth

Apriliabarth


Nombre de messages : 4104
Age : 52
Localisation : cherbourg
Date d'inscription : 07/02/2010

[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Empty
MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5)   [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeMar Oct 26 2021, 18:22

[Vous devez être inscrit et connecté pour voir cette image]
Revenir en haut Aller en bas
MANETON

MANETON


Nombre de messages : 2192
Localisation : *
Date d'inscription : 26/09/2010

[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Empty
MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5)   [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeMar Oct 26 2021, 18:39

Without Frankie seated on it.

[Vous devez être inscrit et connecté pour voir cette image]
Revenir en haut Aller en bas
Tim Ey




Nombre de messages : 20
Localisation : Allemagne
Date d'inscription : 22/05/2013

[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Empty
MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5)   [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeMar Oct 26 2021, 18:41

Merci Beaucoup!!!
<3
Revenir en haut Aller en bas
MANETON

MANETON


Nombre de messages : 2192
Localisation : *
Date d'inscription : 26/09/2010

[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Empty
MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5)   [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitimeMar Oct 26 2021, 18:53

Want some close up ?

[Vous devez être inscrit et connecté pour voir cette image]

Revenir en haut Aller en bas
Contenu sponsorisé





[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Empty
MessageSujet: Re: [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5)   [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5) - Page 8 Icon_minitime

Revenir en haut Aller en bas
 
[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5)
Revenir en haut 
Page 8 sur 19Aller à la page : Précédent  1 ... 5 ... 7, 8, 9 ... 13 ... 19  Suivant
 Sujets similaires
-
» [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 4)
» [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 5)
» [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 1) (Locked)
» [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 3) (Locked)
» [GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 2) (Locked)

Permission de ce forum:Vous ne pouvez pas répondre aux sujets dans ce forum
 :: ACTUALITES :: [GP] :: [GP125 (et 250 Snif!)]-
Sauter vers: