Hi Booney
I am no expert but I will try and share my experiences and what I have learnt with my own carb setup
I mainly run my max at bayford meadow which is also tight and twisty with a good straight,
I run an 8.5 venturi with 5.2g floats and the 30/30 idle jets, I used to run the 3.6g floats with the 60/60 idle jets but found them to rich on idle and the made it almost impossible to get a good low down idle throttle response, the 5.2g/60/60 works much better for me, I also run the k98 needle which is slightly thicker at the bottom than the k27 so it gives a leaner mix at smaller throttle openings, my floats are set at 6mm, now this may not work for you as every engine and carb configuration is going to be different, we have three engines and on the same day we will all be on a different settings, so you have to find what's best for you, you also need to think about your power valve position, I know the recommended opening is at 7500rpm but that also needs tuning to your own particular carb /engine setup you may find having it opening a bit earlier may suit you better, I set my carb up by trying to perfect the slowest corner on the circuit, everyone can drive flat out down the straight, but if you can get your kart pulling out of the corners faster than others you are going to pick up places, as for you question about sacrificing top end for low down grunt, you should not have to sacrifice anything as they are two different phases in the carburetion, the carb on your max is quite simple really, you have three adjustments, idle screw, needle type/position and main jet, now we set main jet first as this governs the amount of fuel that can pass up into the venturi, the main jet should be selected for the particular conditions on the day, different days require different jets, I always start big and work down until I am hitting around 13500/14000 rpm by the end of the straight, the main jet size determines the fuel mix at full throttle as the throttle slide is up at its maximum and the needle is almost clear of the emulsion tube (the straw) so the only thing that is controlling the amount of air to fuel ratio at this point is the size of main jet, so when your happy with your main jet you can work on your small throttle openings, the main jet is not going to help with low down response as the fuel which is being delivered into the venturi is going to be restricted by the needle, so changing the main jet to try to achieve a leaner setting at small throttle openings will not work, although you will notice some difference if you do try it because a smaller jet has a smaller hole which means the fuel is slightly more restricted and needs more vacuum to pull the fuel up, which in turn gives a leaner mix, but by doing this you have altered your full throttle mixture. so once you have the main jet right stick with it, if your rich at small throttle openings drop the needle down, if your on the k27 needle try the k98 it will make it leaner for the same throttle position, if you are closing the throttle right down on some corners you may need a quarter turn on the idle screw either way although the idle screw only has any influence up to about 1/4 throttle, if there is one bit of advice I could give you, it would be to buy the jet tech software, to go through the pain involved with getting your jetting right every time you take the kart out will spoil the fun, I have the software and once you get it right and have it set on the software you will know exactly where you are every time you take the kart out, I just turn up get my weather station out, put the current weather conditions into the boxes, it displays the main jet/needle position and plug type and away I go! I hope you can make some sense of this rabble! and I am sure if I have missed something or got something wrong someone will chip in
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What difference does float height make to Max carb by 'Booney' (16 Apr 2009 @ 17:46)
