140cc lifan pitbike wont rev out

[MaxwellRides]

Brought a 2nd hand 140cc lifan pitbike the other day, fuels been changed and oil. Took the carby of cleaned it all out. when started will rev high when i go to let the clutch go it will take off but with trouble like its starving for fuel? when i go to get into 2nd it will go bit wont rev out ? any input would help thanks!

 

[my67xr]

did you put the carby slide back in the right way around?
the notch/cutout on the bottom needs to face the airfilter

 

[MaxwellRides]

Im not 100% sure will check first thing in the morning but it's really bugging me! thanks for the input ill get back to you asap!

 

[my67xr]

the other thing to check for is vacuum leaks.
start it and spray the join between the carby and manifold with carby cleaner/degreaser/wd40/crc etc.
if the idle changes in any way, there's a leak there.
do the same test at the bottom of the manifold/head join and on the bottom of the carby to the fuel bowl too.

 

[MaxwellRides]

When i start it it will idle alright then it just revs up really high.

 

[MaxwellRides]

When easing of throttle it backfires?

 

[my67xr]

is the exhaust's header pipe done up tight into the recess of the head?
it may need a new copper sealing ring put in?

 

[MaxwellRides]

Done up tight, the carby is a mikuni?

 

[MaxwellRides]

Now when you start it, it will run for 1 second then bog out

 

[MaxwellRides]

Contacted a mechanic he said it sounds like the cdi

 

[my67xr]

did you undo any of the screws on the carby, eg the idle speed screw on the side of the carby, the centre screw with the spring?
if so maybe turn it in half a turn and start it again.
if it is a touch better, then screw it in a bit more, until you are happy with the idle speed.

did you adjust the screw underneath the carby? the one in the little tube on the intake side of the fuel bowl.
if so, you may need to remove the carby again, and screw that one in until it stops, then unscrew it 1.5 turns from there.
then refit it and start it again.

 

[MaxwellRides]

Ok so now it starts for a second and bogs out

 

[MaxwellRides]

Cleaned carby out for the 3934 time, changed the needle setting up 1. Works like a charm! all there is, is abit of throttle lag