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

I.T-Racing a écrit:

What do you guys think of this Engine design With transfer Ports under the Exhaust Port.
My idea is to get a better flow and more gas into the Engine.

You may want to take a look here, I.T.
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A short introduction of yourself and your activities would also be appreciated

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My name is Ivo Trambo born in Germany.
I am 19 years old and 2022 i started with tuning 2 stroke Engines.
I started karting in 2014 since then I've loved motorsport and Engines. I am a good driver with no money so i started tuning my own engines because the Racing teams want 1000 only for a tuned cylinder so i was reading some books and in the Forums.

I started tuning 100cc kart engines because i had no money, with a great success.
With the knowledge i get from Reading books and Forums i found out how to modify engines to get Great HP with a big Powerband.

My first Engine i made was a 1983 100cc TKM Rotary valve it has a Huge powerband it pulled from 5.000rpm to 21.000 without any problems but at 19k the Engine had a big lose of power but it had the Great Low End torque.


Everyone I let drive this Engine Said it is one of the best 100cc engine they ever Driven.

Then i started with Modifying my 125cc TM KV95 Rotary engine. I want to make Max power possible.
This Engine is a Beast. I was driving with the old small Exhaust but i will maybe build my own Exhaust sometime. The Engine has more power than every modern KZ kart and it had also an huge powerband which is bigger then every modern KZ Engine. When i got the Engine the powerband started at 9000 like the new KZ engines, But after some tuning in the Cylinder and Changine The Rotary Valve it now has more Peak Power and the Power started at 7500rpm, after tuning this engine i had with the same Gearing instead of 14500rpm, 17000rpm on the Straight. The KV95 is now 20kmh faster than the modern Shifter karts from SRP Racing in Kerpen on the Straight with the same weight.

Welcome Ivo !

Hi Ivo, thanks for the extensive introduction. Do you happen to have any power curves?
And can you tell me your Postleitzahl?

Sadly I dont own a dyno but i will build a dyno if i have time for it.

I live near Cologne

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Lovely bikes

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I now have a dyno Result from my Friends dyno with my TM K9C engine 1 curve with original Cylinder and 13cc Combustion Chamber and 4° Piston and the other with My tuned Cylinder

I drive now with a 30mm carb. I think with a bigger carb i maybe got a little more power


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I will try this combustion chamber to get a bigger powerband it has 7cc Volume and is designed for 0° Pistons

I would rather use a different combustion chamber shape, but your power curve looks excellent