So this is a fuel\air leak between throttle shaft and carb body?
Not a typical inlet needle leak?
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The fuel came out between throttle shaft and carb body. Right behind the locking plate
Good question - I dont know does a leaky inlet needle make fuel come out this way 
The needle has rubber tip, feels soft and doesnt have burs or scrathes. The seat looks ok. Same with my old carb
The carb only leaked when the engine was screaming its lungs out - when I was hooning around the track
It didnt leak while the engine was idling. Or if it did it was very minor. There wasnt visible fuel flow or drip coming out of the carb when engine was idling
It never ever leaked while the kart was in storage or stationary at the pits
Hello, this is Tillotson with a reply. From what you described, the fuel is coming from the enrichment circuit. It flows through the circuit and the throttle shaft into the venturi, not from any needle. It is not exactly a leak, as the original version of the carb had that as a passageway for the fuel but we decided to block it off with an O ring because it looked and felt like a leak. The extra fuel should not affect performance, except that you would need a slightly leaner setting on the needles. You probably have a worn or damaged O ring. Try changing that.
Regarding performance with the original carb you were using, when was the last time you serviced it? We normally suggest a complete service (diaphragms, gaskets, inlet needle, seat) with an RK kit at least once a year, twice if you are a heavy racer. The diaphragms and gaskets should be checked more often. Heavy or hardcore racers replace them after every race weekend, but we suggest every two or three for optimum performance, or at least checking them that often and replacing as needed. The diaphragm is ready to replace when it has lost some of its shape or bounce.
Dear all,
Hope everyone is well and sorry to be out for a long time and with even more that I said I would come with feedback.
So long story short, replacing the inner spring caused me a lot of trouble with 2 different carburettors and I won the last round of the Skusa 175 with the original carburettor setting (had to borrow this one from a friend of a friend).
My feedback is that it if you change the spring to a heavier one, it does increase the pop-out pressure, and it feels good, however, in my case, I got lost with the carburetion. A little tiny small, millimetric change in the low needle would drastically change the feeling of the engine, sometimes it was asking for more gas, and in another lap, it was bogging in excess of gas.
I don’t know how faster the other guys here from the forum went changing it to a heavier spring, I think that, indeed, it could make you faster, but you would need to make a lot of tests with the air spring, more, less, gas and stuff and as I just use the 175 to race, didn`t have time to do that.
End of the day, managed to win the last round using the standard configuration that the engine is sent with the fastest lap. Advise to guys looking to do this change, you gotta do a lot of testing and see if it indeed helps you with times.
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