Iame kart motor with V-shaped throttle plates

[Belgian1979]

I was at a karting event and they were talking about a new Iame kart motor that had V-shaped throttle plates made out of carbon fiber (for the flexibility apparently) which, according to the explanation, was to combat intake reversion. The thing had a lot more hp than normal.

Anyone here have any idea about that throttleplate design. Seems interesting.

[miniv8]

What, like a reed valve?

[Belgian1979]

Unfotunately I didn't get a clear view at the throttles, only a spare throttle plate and it looks like that. No idea how they open them though.

Thing was a blast to drive. 180-190 km/h on the straits. Around 50 hp. Incredible torque for that small an engine. Different sound as well.

[j-c-c]

My 2 cycle Mc101? Kart motor in 1968? had a V reed valve set-up as pictured by the OP, but its been awhile. I thought it was fast then. The valves varied between SS and phenolic, don't see much upside to CF, they both would fracture/fatigue and motor went flat, always near the end of a heat.

[Belgian1979]

My 2 cycle Mc101? Kart motor in 1968? had a V reed valve set-up as pictured by the OP, but its been awhile. I thought it was fast then. The valves varied between SS and phenolic, don't see much upside to CF, they both would fracture/fatigue and motor went flat, always near the end of a heat.

Well,they told me that was one of the reasons they used carbon fiber. It got used quite extensively and didn't quit once.

[1989TransAm]

2 cycle or 4 cycle kart motor?

[555RAT]

Thanks! Got a kick out of that, I'm at work on a Friday and that's funny.

[Belgian1979]

2 cycle or 4 cycle kart motor?

2 cycle

[Truckedup]

I believe reed valves been used in 2 stoke high performance engines since the early 1950's....There's also rotary valves...

[ZEOHSIX]

Maybe something like a Kendig or Preadator carb? I'll stick to my Mikunis and Kehins on my 2 strokes.....already have too many $$$ tied up in jetting for those platforms.

[Belgian1979]

I believe reed valves been used in 2 stoke high performance engines since the early 1950's....There's also rotary valves...

Don't know. Most items I see are Rotax's which have a carb with regular throttle blades.

[Juho_]

They are not throttle blades.
It probably has a regular slide carburetor and a reedvalve (what you are talking about).

Carburetor might be Dell'orto VHSH 30mm. 125cc 2-stroke shifter karts are limited to use a 30mm carburetor. In some race classes.

125cc shifter kart engines, like TM KZ10 has approx. 50hp at the sprocket (45-50hp mostly, hardly anywhere over 50hp though).

[Belgian1979]

They are not throttle blades.
It probably has a regular slide carburetor and a reedvalve (what you are talking about).

Carburetor might be Dell'orto VHSH 30mm. 125cc 2-stroke shifter karts are limited to use a 30mm carburetor. In some race classes.

125cc shifter kart engines, like TM KZ10 has approx. 50hp at the sprocket (45-50hp mostly, hardly anywhere over 50hp though).

I didn't get to look it over, but they said no slides were involved. Don't see how it would work, which is why I asked in the first place.
Was a non-shifter btw.

Anyway, maybe I understood it wrong.

[j-c-c]

My 2 cycle Mc101? Kart motor in 1968? had a V reed valve set-up as pictured by the OP, but its been awhile. I thought it was fast then. The valves varied between SS and phenolic, don't see much upside to CF, they both would fracture/fatigue and motor went flat, always near the end of a heat.

Well,they told me that was one of the reasons they used carbon fiber. It got used quite extensively and didn't quit once.

Seems odd to me, the pictured reed intake one way valve reed needs flexibility in order to open under lowest pressure differential, in order to maximize crankcase/cyl filling. CF's main attribute is usually stiffness. I would think high rpm cyclic bending would be an opposing feature. Lightweight doesn't seem to apply here. The fracture demise I mentioned, seemed to be back in the day from the chosen material slamming shut/hard onto its sealing surface and likely bouncing, leading to progressive fracturing. The SS valves gave more power since I think they opened easier then the phenolics, but as the SS disintegrated over time, the motors did not like ingesting flakes of SS at high rpms, vs phenolics which did little interior motor damage, other then slowly lose sealing and power output. This is from memory of over 5 decades ago.