Rotax Max Carb


Do you service your carb enough?


The answer is probably no. Should you? Absolutely, yes! Your Carburettor is one of the most key elements to performance on track, if slightly blocked the carb will cause you to bog down off the corners, and you wont pull at the end of the straight.
So what do we mean, “service”?  Everyone will have a slightly different view here, some go to the extremes, we however, trust simple maintenance every couple of days. This keeps your carb in great shape and keeps the power coming on strong!
How do we do it then? Your carb is built up in simple terms, with jets and these jets have tiny inlets and outlets the size of a few strands of hair, which very easily get blocked up, with fibres floating around in the air, muck and indeed any dirt which has managed to make its way past your various filters, and believe me they do!
You have 4 jets in total, all of which are easily found inside the bowl at the bottom of the carb. Lets go!
  • whip the bowl off with your 4mm allen key and remove the floats carefully
  • Remove the 3 jets, then seek out the hidden idle jet buried deep below one of the other 3, this is probably the most important. Remove this with your tiny screw driver, take your time, if its tight, spray a little Wurth 2040 or WD40 down it. Try again in 5 mins.
  • Remove the fuel filter - 12mm hex bolt on the side, sometimes you have another filter behind this.
  • Remove the air screw and the spring behind it….don't loose the spring!
  • Remove the float needle, and the gasket that sits below it.
  • Brake cleaner the carb and jets, and airline the inlets and outlets, jet housings etc accordingly, don’t be shy on the brake cleaner! Give the carb a proper air line everywhere, make sure its immaculate, and then make sure you air line the jets thoroughly. 
  • That it!
  • Carefully reconstruct your carb the opposite way you stripped it down!
 A standard setting for a Rotax engine is: 4 complete turns out on the idle screw, and 2 complete turns out on the air screw
Happy wheel spin!  
Now - going a little further and working in the same area, its wise to remove your carb slide, needle and clip...give them all a good clean off and make sure the slide is free moving inside the carb
Finally - there is a rubber seal in the carb cap where the throttle cable sits, replace this every now and then. If it leaks, air will seep into the main chamber when its not wanted, and you will have that boggy un responsive feeling return! 
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