Jetting advice for Polini 177cc and DellOrto PHBH carb


Can anyone give me some advice on which jets to use in a DellOrto 30mm PHBH carb? [:|]

I have a 125cc PX motor with a Polini 177cc racing kit, Mallossi manifold and reed valve kit (inlet manifold has been ported by PM tuning) Mazzuchelli racing crankshaft and a scorpion exhaust. Also, any tuning tips would be great as I don't think I'm getting the fuel and air mixture right.

With all these modifications and money spent, I would like the scooter to run the best it can.

Thanks in advance

Matt [Y]


Thanks for your reply. I feel very stupid when I ask "What does all that mean?)



hi ...


no problem !


what do you dont understand ?

the names of the jets ?



I know the 125 - 138 is the jet size but it do not understand the other numbers. Sorry



hi mate... just out of interest how did this setup work for you.. im in the process of doing the same.... any tips, or advice... anything you came across that i might have missed, 


my current setup ( well i say setup its all still in the box waiting to be built..) is lml reedvalve crank case, flowed crank, worb5 polini 177, dellorto 30 phbh carb... scootrs manifold, polini up gear kit, and scorpion exhaust.. 


thanks jake.



Thanks, I have looked on your website and seen the pictures and now it makes sense. I will play with these settings and see how the scooter runs.


Thank you for your help, I will let you know if successful



hi ....

i think that the beswt for your setup is:


1. 40415000

2. mainjet between 125-138  /  4010125 4010128 and so on

3. Idlejet 4010055

4. Needle in second position 40511 or 40508 (check the plug if its to fat or to lean)


good luck


perfect !!!



good luck



hi  !!


please try to che the item codes in our website

so maybe you se with the pictures what i mean !

did you tried to dismount you carburetor ?