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

Bonsoir Frits

I have add an Aprilia 250 V2 crankshaft as at this time we were thinking to copy it with my friend , there were no washers on the side of the conrods , but there were something a hard coating very thin , I would say nothing , may be DLC ? Yesterday I was speaking with Francis Payart he know this but he do not what is this material . Two washers less it is two mm more for the crankpins inside the wheels .
All the best Jean-Paul

D'après cette description et tenant compte de la faisabilité: revêtement très dur, mince et localisé autour de l'alésage de l'axe, je soupçonne une projection plasma de carbure de tungstène ,de chrome, de titane ou autre substance régulièrement appliquée sur les aubes de turbines de réacteurs. Il y a une société très spécialisée dans le coin de St-Etienne, nous y faisions revêtir des rouleaux de grand diamètre pour améliorer le grip sur des bandes de tôle lisses à entraîner. J'ai perdu le nom pour l'instant mais je doute que ce soit OK pour de la pièce unitaire. J'ai retrouvé: PRAXAIR surface technologies.St-Etienne.
Dan

Frits Overmars a écrit:

Motors31 a écrit:: Hello Frits , I probably didn't understood something in FOS exhaust concept , you propose for speed of sound to start with 550 m/s but on wikipedia I've found 340 m/s .

Wikipedia is talking about the speed of sound in ambient air at 20°C.
I am talking the speed of sound in exhaust gas of about 600°C.

Thanks Frits .

Nombre de messages : 106 Localisation : Biblis Date d'inscription : 14/01/2017

Hello,

i´ve got another question for Frits.

Regarding the carburetor mounting on a two stroke.
It´s common to use a rubber mounting to install the carburetor.

You think it´s Ok to slot the carburetor into a thin metall ring, welded on the rotary valve cover?
As you see in the picture space is very little on the Maico 250 engine case. With a metal mounting i could weld a section (about 90°) of the valve cover including the carburetor mounting direct on the engine case. This is saving space and the flange to the cylinder would stay stable.
The rest of the rotary valve cover could be included to a seperate section, allowing it to mount the rotary valve disc.
I fear that resonances / vibrations will foam up the fuel inside the float bowl.
What are your thoughts about that aspect?

Best regards,
Bernd
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Döllinger a écrit:: Regarding the carburetor mounting on a two stroke. It´s common to use a rubber mounting to install the carburetor.
You think it´s Ok to slot the carburetor into a thin metall ring, welded on the rotary valve cover?
As you see in the picture space is very little on the Maico 250 engine case. With a metal mounting i could weld a section (about 90°) of the valve cover including the carburetor mounting direct on the engine case. This is saving space and the flange to the cylinder would stay stable. The rest of the rotary valve cover could be included to a seperate section, allowing it to mount the rotary valve disc.
I fear that resonances / vibrations will foam up the fuel inside the float bowl. What are your thoughts about that aspect?

Fitting the carburetor directly to the engine case will definitely bring a foaming risk.
Here is a method for an ultra-short carb fitting without metallic contact.
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Wow, this is very clever !

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