Carb float level for fuel to start/stop entering bowl

2 Stroke Kart Engine Forums
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Hello friends. Managed to get out to the track two times now, for my first excursions with my self-assembled BirelART shifter. Concept Haulers Motor Speedway in Norway, IL. Great place and people. Learned a TON about this kart in my short time out there. TON more to learn. Starting with…

…my Dell’Orto VHSH 30 carb, which feeds my IAME X30 125cc shifter.

(Does anyone run this same engine/carb combo? Just curious, as I think I’m going to have a few more questions, and according to the Concept Haulers people this is not a common arrangement.)

Here’s my question for today. My fuel valve needle has a spring loaded pin in it. I have my 9g floats set to 11.5mm as measured from the gasket, held upside down, as per my Dell’Orto documentation. What I observe is that when my floats are at 11.5mm, they are compressing that spring loaded pin around halfway - in other words, the floats have to drop a bit, somewhere around 1.0-1.5 mm, before that spring loaded pin comes fully “out” and THEN the rubber-tipped end of the needle valve actually starts separating from its seat, thus clearing space for fuel to enter the bowl. So my question is, is that 1.0-1.5mm travel before fuels starts entering normal…or should I bend my float assembly so that (for instance) ANY downward movement on the floats at all will result in the needle valve allowing fuel to enter? If the floats should be set at 11.5mm, at what distance exactly should they drop to before fuel starts to enter through that valve?

Guys, can’t thank you enough for any help. Hope this question makes sense, please let me know if I can help you help me. Trying to teach myself carburetors and I’m getting there but I’m on a learning curve. Thank you!

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that “play” is already accounted for and completely normal. Set your float at 11.5, measured to the sealing surface of the bowl, with the gasket in place. That height already accounts for the fuel needle “springiness”. That’s why you want to measure it with the carb upside down so the floats rest on it. There is no wear on that spring, at least none worth compensating for. The only thing to look for in that area is the rubber tip, as certain fuel/oil combinations tend to deteriorate it so inspect it once in a while

For a good visual, download the manual of the screamer I, there’s a full writeup and a picture that will clear any doubt, in case the X30 manual is not clear

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Thank you! I really appreciate that response. That gives me the confidence I was hoping for, to move me forward in understanding this carb and engine. One more element I can call a “known” that allows me to move on to the next unknown. I have a few good documents on this thing, but I always wonder how much these docs (especially those translated from Italian to English) assume some basic/prior knowledge that I may not have. So great to have this forum as a place to confirm things. Thanks again and more to come I’m sure.