Emulsion tube and jet

[Abtheman28]

Hi there, what would you guys recommend in regards to correct jetting size for a modified gx200 clone motor? I'm currently using a 140 emulsion tube and a 0.37 main jet and getting carbon deposit on the plug. Would you think I'd be better off sticking with the jet I'm currently using but change back to the stock emulsion tube? My understanding is the 140 tube enrichens the air fuel mix due to less holes on tube? I have a 0.36 main jet which I'm still yet to trial but I want a reliable kart at high rpm as well. I'm using a standard carb but bored to .615

 

[zbuck]

Hi there, what would you guys recommend in regards to correct jetting size for a modified gx200 clone motor? I'm currently using a 140 emulsion tube and a 0.37 main jet and getting carbon deposit on the plug. Would you think I'd be better off sticking with the jet I'm currently using but change back to the stock emulsion tube? My understanding is the 140 tube enrichens the air fuel mix due to less holes on tube? I have a 0.36 main jet which I'm still yet to trial but I want a reliable kart at high rpm as well. I'm using a standard carb but bored to .615

Do a plug check. That should tell you which way to go with your jets. Also what kind of air cleaner is on that engine and is there a header envoled?

 

[OzFab]

You will get carbon deposits on the plug regardless; what matters is the colour of the carbon:
White = lean (not enough fuel)
Brown = good mixture
Black = rich (too much fuel)

 

[Abtheman28]

I have done the plug check and its a black carbon deposit (running rich). I am just a bit unsure if i want to lean it off to much with running high RPM, but thinking ill give the .036 jet a try instead of my current 0.37. I am running a pod style airfilter which is fitted on one of those billet adaptors. I also have a J pipe freeflowing exhaust system on the motor as want it to breathe as best as i can make it. Thanks for your help

 

[OzFab]

I have done the plug check and its a black carbon deposit (running rich). I am just a bit unsure if i want to lean it off to much with running high RPM

Well, there's the problem; a full plug test means cleaning the plug & driving the kart (the engine needs to be under load) at WOT (to reach the high RPM); if the engine is only free revving at low RPM, you won't even get close to a true reading...