Jetting for Malossi 166 kit

Hey, I just put a malossi 166 kit and Sito Plus pipe on my `79 P125X. The Malossi instructions (if you can call them that) say that the max main jet for a SI 20/20 carb is 115 and they include that in the kit. However, for break-in, we are not modifying the case or cutting the crank, but just bolting it on. So does anyone have any guesses as to a proper range of jetting for running this setup? Thanks in advance for any help you could give.

Hi there,
we recommend a jet from 118 to 125 for your carb.
Anyway it would be a very good idea to replace the 20mm carb at least to a 24mm, better a 26mm. That Kit is definitely too large for the small carb…
Good luck!


 I am also having problems on a PX 125 E I have just got. This has the 166 kit, no mods to crank case and standard crank, revolver exhaust. This also has the 20/20 carb on.


Jets are: 48/100 idle, BE4 mixer, 140 atomiser and 125 main


what would you recommend. I will be swapping to a 24/24 eventually but just want to get by in the meantime.


Thanks in advance