[GP125] All that you wanted to know on Aprilia RSA 125, and more, by Mr Jan Thiel and Mr Frits Overmars (PART 4)

Frits Overmars a écrit:

Panas a écrit:

So Frits was your personal assistant.

That's right Panas. I could fry the best chips that Jan ever tasted. He said so himself .

Frits Fries!The tastiest chips ever! with extra synthetic 2stroke oil!

Hi!


I read part 1 and 2 of this topic a year ago.
I wasn't able to catch up on the rest so I have a few questions:

Has anybody continued developing the FOS or the 24/7-intake system?
Also, did anybody built RSA replica cylinders?

Yes, somebody built them.

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

Nice!

How do they perform? Which pages should I read?

Go to
'Technique' => Moteurs => Fpe (superkart)

that's mine. 70cc

How much, do you think, would it affect the performance of a rotary valve engine if you offset the air intake?

Here is a picture to show what I mean:
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It's fairly essential that the inlet tracts on the disc valve covers line up with the inlet tracts in the crankcases

Or perhaps I misunderstood your question

Best Regards

Ian

I was talking about a hypothetical engine that has the intake (including the inlet tracts) offset from the usual placement and I was wondering how much power you would lose compared to the regular design.

Hi vin 97,

You must have a reason for considering putting the inlet tract anywhere else than in the shortest straightest possible position, directly beneath the centre of the cylinder, through the transfer ramp area.

Might help if you explain what you are trying to achieve and why and include a sketch of the route you expect the inlet tract to take.

It would lower the carbs on square four engines (specifically the rg500), allowing it to fit further back in a 250 frame without cutting it.


Anyway, I am not an engineer, I just wanted to ask you if something like this would be possible and if so, what compromises there would be.

Hi Vin97, sorry, it just wouldn't make any sense at all from any perspective.

Ian

I just encountered this link and I am so impressed that I am posting this warning on all forums that I attend:
[Vous devez être inscrit et connecté pour voir ce lien]

The spray we use in my job (brake cleaner) contain in french (sorry) hydrocarbure aliphatique , I think tetrachloruethelene is forbidden to sold since many years for private person . But this remain dangerous too .

So you think it's completely impractical to impossible?

Frits Overmars a écrit:

I just encountered this link and I am so impressed that I am posting this warning on all forums that I attend:
[Vous devez être inscrit et connecté pour voir ce lien]

I've seen his write-up before.

But, I read it again. It's good info and everybody should read it.

I hope he's doing OK, but it was another case of pilot error.

Read the F'n label, or be a moron.

You wouldn't pour the jug of Diesel in your race bike ?

If that welder was politically connected to the Obama clown car in what's left of our former Constitutional Republic, he could sue the evil manufacturer. That can should have a child-proof cap, bullet button spray noozle, and a government goon included to change his diapers.

For all those medical tests, just send us the bills.

The stack of debt is already 18 + TRILLION, so what's another hundred thousand, or two.

We're NEVER going to get it paid, so pile it on mate !

BTW, about NOT paying bills....

I hope the Greeks tell the ECB, IMF, and the rest of the commie bankers to shove it. It's doubtful, but we'll see.

Tomorrow is our Independence day in USA.

It started out right, but things sure went to Hell.

NASCAR is a joke. If they want to kill the real history & Southern Roots of the sport, just put drunk illegal aliens in the cars, hoist the Mexie / Viva la Raza flags all ' round the pits, and let Univision run " dump Trump " commercials every five minutes !



Yeah, it's all a joke, but I'm keeping my Johnny Reb flag.

vin97 a écrit:

So you think it's completely impractical to impossible?

Hi Vin97

Completely impractical and pointless . . . . . . but there's not much that's impossible given the skill, the funds or both!

Cheers

Ian

Ok, thanks for your answers!

Bob van der Zijden a écrit:

Please wake up two stroke youngsters , show some guts and do try TORQSOFT.NET...

Are you serious?
[Vous devez être inscrit et connecté pour voir ce lien]

Man, this software reminds me to this:

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

They promise "we will design the perfect exhaust system for you" and then they want to know the number of ports. Really?
Where is the scientific context between port number and performance?
And all pictures just showing straight cones, no twisted ones.
So they can calculate "perfect" exhausts, but aren't able to compute twisted cones?

I recommend to spent 35€ in cone layout (https://www.conelayout.com), buy a sheet of metal and use the fos pipe calc.

Some people think that the data in this picture is enough. Yes it is, you can calculate an exhaustpipe. But it is impossible to be sure about the result. No matter what incredable formules or ingenius thoughts are behind it. The mean reason why this is impossible is the lack of information of portsurface for tranfers and exhaust. Only degrees is by far not enough. That is why it is very doubtfull and in reality a lucky shot, if the chosen rpm does fit to the engine and so if there will be any power or not. Succes and espected power of a good calculated exhaustpipe depends for more than 50% on the accuracy of that subject. So even if you are professional, you have to calculate the exact right rpm, before calculate the exhaustpipe itself.

Sorry can't attache a picture, but here you can find it too. [Vous devez être inscrit et connecté pour voir ce lien]

Frits Overmars a écrit:

I just encountered this link and I am so impressed that I am posting this warning on all forums that I attend:
[Vous devez être inscrit et connecté pour voir ce lien]

C'est clair que ces produits sont dangereux!c'est mentionné sur les aérosols ( en petites lettres mais c'est écrit), ça sent tellement le trichlo ( pratiquement interdit de nos jours), il est même écrit en gros sur le bidon: "à usage professionnel". Un soufflage à l'air avant de souder est une bonne précaution quand on est pressé. Et puis du nettoyant freins, c'est fait pour nettoyer les freins, pas pour dégraisser des pièces grasses avant soudure. Merci Frits de ce rappel pour nous, bricoleurs touche à tout
D'autres trucs pas saints: l' isocyanate contenu dans les peintures et produits PU; verser de l'eau dans un acide concentré (batteries); faire un mélange musclé de nettoyage avec de l'ammoniaque et de l'eau de javel( chlore): mortel. Ne parlons pas du barbecue ranimé à l'alcool, voir essence, si si j'ai vu faire .
Prudence, et ne rien faire c'est mieux.
Dan

anyone looking for a cheap porting tool, I'd recommend looking at dental handpieces. thought already a while about buying something like this :

[Vous devez être inscrit et connecté pour voir ce lien]

but as my dad is a retired dentist and now has plans to move to a smaller house, he's old aquipment needs to go and asked a 90° piece to try out (he still used them for his modelling trains    , and still has loads and loads of burs/drills/polishing stones/...    ).

it works with a compressor so I just used a preasure regulator and stuck the tube in it

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

could go to about 2bar before the original hose starts to blow up and gave it a try with a mill in it. the cut-out in the 2mm thick iron plate was done in about 2-3 minutes :

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

to show how easy it is to get in the transfer ports : this is in a 39mm moped cylinder :

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

when pushing to hard, the drill stops turning , and the bigger the diameter the less power you have before it stops. with the sanding stone in the picture, you won't be able to take away much material (only tried in on the iron casted cylinder, might be more of use in an aluminium cyl), but small diameter mills like in the first picture are realy usefull, and the sanding stones with bigger diameter can than be used to make the surface more even.

China-made dental pieces like this can be bougth very cheaply on ebay (for example [Vous devez être inscrit et connecté pour voir ce lien] . they probably won't last as long as much more expensive brand equipment, but at 10£ a piece worth a try. there are also pieces whith heads that can turn to give you different angles. you'd have to source the part to connect the hose to the piece but maybe the china-ebayer can supply it to. or you could go for an electric like in my first link.

I would not recommend dental hand pieces, Jan. In my experience they are too fragile for cylinder work. The bevel gears in particular won't survive very long.
I once got a box of used dental handpieces for free and used them to modify a 125 cc cylinder. When the cylinder was done, the box was empty: all five sets worn out.

What I will recommend, albeit in a sturdier form, is the swivel head. It's great; it will enable you to get to every imaginable spot.
[Vous devez être inscrit et connecté pour voir cette image]

my dad suggested the same thing, but as it's for free just like you had yours, better to use and destroy them than to take them to the iron scrapyard .

time will tell