Pilot and Main jet  By  jonwaylee (Read 1,930 times)

Why are you changing THEM??? Did you do some mods that require chaning them??
Alleyoop

Just go up 2 sizes on the Main Jet leave the pilot alone that will be fine. Pilot jets only need to be changed if you put in bigger valves and or bump up the displacement.
Alleyoop

Hate to be a little Brass but those are young pups that do not know motors. Many believe well just put a 750 holley on this puppy and I will fly high. What they really did is actually loose power but they don't know it. And if you know motors you can tell just by the sound.

My Trike you see in the picture weighs in at 350lbs and my butt of 180lbs and it smokes some 250s and it is just bored out to 182ccs from 149.6ccs and I have every performance part on it you would want. Even a built 1 1/4 header pipe going through a SuperTrapp Muffler. I have a #38 Pilot Jet and a 122.5 MAIN JET, and get this a #125 Main Jet was to much fuel. It will run with a #120 Main Jet but you ALWAYS want to be just a little on the rich side on the top end so you do not damage the motor.

A 150 stock MOTOR with just a Free Flow FIlter and Free Flow Muffler will take up to a 115 MAIN JET and depending on the motor that may be to much it may need a 110-112. That is a lot of fuel being sucked in you may not think so but it is. They come Stock with a Main Jet from a #103-#105-#107.

Alleyoop

And that is the problem with the JET SETS, they cannot sell 120s and above not to many motors will take such a big jet so they sell them in the sets of to get rid of them. They know good and well they will be useless to you. The only ones you will find that work will be your 110 and 115.
They know all the tricks on how to sell parts but nothing about how things work.
Alleyoop

Thank you Jeffery5568,
Nothing like a real honest response. It is not magic and it is up to the motor as well some put out more compression than others. You can take two brand new motors of the same model and one will run better than the other. These motors are not built with tight tolerances so every motor runs different and put out different power. All you can do is try and get the most out of what you were delt.
Alleyoop

I believe jetting goes by many factors motor size and air flow, i run a 110 jet with a 24mm carb on a 50cc modded with a 52mm piston and big valve head and all the works, most would say thats too big but no its not it hauls and runs smooth and plug is perfecto all scoots are different.

There's a lot you can do with the AF screw.
In most conditions you can optimize fuel flow, for the most part with the AF screw.
If it runs perfect at idle, but lean at WOT, you can make it run a bit richer at idle (less good idling), but running better over the rev range.

Just at WOT, if your main jet is too small, it will run a bit lean. You could compensate with a choke (if you have it)..

Any of the experts want to comment on compensating a lean running bike by opening the choke a bit (reducing the airflow a bit), until the bike reaches better performance?