primary main vs secondary main

If i understand right the primary main is pretty much a slow jet correct? and then the secondary main is the actual main jet? Is upjetting the primary main ever required? Feel free to school the newbie

I'm still learning too but i believe what you say is indeed correct


I'm sure it depends on many factors wheather it needs upped or not, airflow, weather & barometric pressure will all play a factor & thats just some variables

I also believe that is correct... the secondary is basically the main. But I'm not sure if it's standard on all carbs with dual mains.

The primary is sort of in-between the idle jet and the secondary main. So there are actually 3 circuits to adjust and clean (at least 3).

And yes, in some instances you may have to change the primary. I had to use larger primary and secondary on some KZ400 carbs to run pods and open exhaust. However getting the exact right jetting requires a lot of time and testing for CV carbs using multiple mains, and changing one will affect what the other will need to be.

I increased the size of both primary and secondary when I had pods on the 750/4

thats exactly what im attempting with this is pods err pod single cyl. But for upjetting would the same +2 sizes per mod albeit exhaust pods or both also apply to the primary along with the secondary?

moke wrote: thats exactly what im attempting with this is pods err pod single cyl. But for upjetting would the same +2 sizes per mod albeit exhaust pods or both also apply to the primary along with the secondary?

Experiment, observe, deduce.

Start with changes in the 10% range for the secondary main, and maybe 5% on the primary and pilot.