I've got a peugeot speedfight 4 50cc and want to upjet it. I've got a 75 jet and a set of 60-68 jets but not sure which one to use. Can somebody let me know which one to use and what I'll have to adjust on the carb to take the bigger jet and make it run properly. Its got a dellorto 17.5 carb on it and Its got a yasuni exhaust . Cheers
Start with biggest jet, try it and run wide open throttle, if it splutters it may be too big, if it revs and keeps on revving up jet . Always start big and work down until it feels right, check spark plug colour as it needs to be a dark choc brown clour.
Do I need to adjust air mixture screw and needle settings I tried the 68 jet yesterday and it was spluttering under full throttle
Mixture screw only alters bottom end pick up, needle position alters mixture over the whole range. You should be able to feel, hear what it's doing and what it needs. It might be roller weights that wrong for the pipe? Air filter ? There's no fixed out the book setting, you've got to find what works !
I've got a naraku 2000 torque spring in it and ever since I've had that in the bike runs rough under full throttle with it could this be affecting it
