Why do I need such a big jet?

2000 aerox
50cc
Dopler exhaust
Polini reeds
Pm tuning crank
17.5mm dellorto rep
Standard airbox

As standard the pre 2003 bike had an 86 jet. Mine has a 98 which is a reasonable upjet from standard, but why is it that 2003 onward bikes have a 62 as standard? How can it run with such a huge down jet?

I ask beause I see people with newer Aerox's and zips that can run a 72 jet with my mods. My 98 jet is making it drink!

Thanks

 

They probably changed the model/size of the carb.

 

They changed from a 12mm delly to a 12mm gurtner, but even when people change to bigger cabrs they still have a much smaller jet.

Maybe it's something to do with the auto choke carbs vs manual choke?

 

Bump?

 

you prob got a air leak cos a 98 with standard box is nuts mine wouldnt even move if i changed mine to tht i got a 75 with 21mm carb n standard box have u tryed puttin a 70-75 in your bike see wat happens?

 

Theres no air leak, it's all been rebuilt with new gasket, seals and other parts.

What year is yours? My standard jet was 86, 12 bigger isnt exactly unheard of for a sports exhausts.

 

I thought the same. My rox had a standard jet an i measured it to a standard gurtner jet an even though the numbers are different the holes are same size