Need help tri-zinger carb jetting ?????

[bushwacker51]

I own a yamaha tri-zinger. Its my sons trike. I have rebuilt the motor and put on a dg pipe. Recently I put on a clamp on air filter and did away with the air box. I also put on a set of boysen power reeds. I drove it and it ran hard. I had the needle in the carb set at its lowest setting( making it richest seting). The plug barley had a tan color to it. I had a spare jet so I enlarged it allowing me to run the needle in the middle setting. The plug is a nice choclate milk color. The motor kind of fumbles until it cleans out. It seems like it runs great when there is harldey any color on the plug its almost white but I know that has to be bad on the motor any suggestions. Oh yes the carb is new also. Thank you ib advace Glenn O.

[Unclediezel]

No air leaks?????- make sure your intake boot is sealed, -----Motor was rebuilt---Im guessing crank seals were replaced?----You may have to play with a few main jets until you get it right--but the needle clip position should stay constant.

[bushwacker51]

I put all new gaskets and seals in the motor. I am not sure about a air leak. The carb bolts to the end of the intake tube. I wouldnt imagine it would be leaking there. i have been using the setting on the needle to richen or lean out the motor. It just seems to run best when its very lean and I am scared it will blow. Glenn O

[TimSr]

You need to do a full thorttle plug test, and then a half throttle plug test, and setup the main jet first. What I suspect youll find is that your main is okay, but its running rich at half throttle causing it to load up at the bottom. This can be corrected by leaning out the needle setting which affects the range from coming off idle until about 3/4 throttle. Once you get the needle dialed in, you set the air screw for best throttle response off idle when you blip the throttle.

[bushwacker51]

Thank you for your help. once I enlarged the jet it was running richer so I had to lean out the needle. I will set the needle one setting higher and see what that does. I also assume when you mean plug test thats when you run it full throttle then cut the gas and check the plug?. Thanks for your help. Glenn O