138cc Engine Problems

[Pro70]

G'day guys....

I have a lifan 138cc engine in my pitbike and has reently been farting and spluttering. The engine seemed to overheat quickly n i found out the needle was on maximum lean so i moved it up 2 notches. But now it is extremely hard to start and once it does start it struggles to run both choke on and off.
It will cough and splutter as you increase the revs to the stage it nearly dies...if you then back off it goes back to running smooth at idle...

Anybody with any ideas is appreciated...

Thanks

 

[Kourt]

Hey bud i have the same motor on mine i had exactly the same problem. When you move the Pin around it will go off tune. So you have to ajust your airscrew.

So here's what i think you should do- put the pin back to its original running location and use the air screw to ajust the mixture.

The air screw is located at the bottom of the carb on the side it attaches to the motor. The best mixture for these engines is- screw the air screw all the way in then out two rotations- this is a good starting point- then you can lean out or richen the mixture depending on what you what

Remember
- Screw In =lean
- Screw Out= rich

 

[Sidney]

yeah I think you mean it was fully rich? if the E clip was at the bottom of the needle is it rich

 

[Cactus Jack]

G'day guys....

I have a lifan 138cc engine in my pitbike and has reently been farting and spluttering. The engine seemed to overheat quickly n i found out the needle was on maximum lean so i moved it up 2 notches. But now it is extremely hard to start and once it does start it struggles to run both choke on and off.
It will cough and splutter as you increase the revs to the stage it nearly dies...if you then back off it goes back to running smooth at idle...

Anybody with any ideas is appreciated...

Thanks

Hey mate , you've been running that 138 engine for months now from brand spanking new so you'll most likely need to check and adjust the valves . If the valves are being held off the seats ...... it'll be a bitch to start and will hic and pop ...... plus if you persist in running it you'll over heat it and burn a valve out or melt the piston ........

Raising the "E" clip on the needle LEANS out the mixture and lowering it enrichens it .........

The float needle and seat can wear ..... altering the fuel level in the float bowl or the idle fuel screw can also lose adjustment from vibrations over time .......

Nothing stays tuned forever and needs regular tweaking ...... just like guitar strings ....... LOL .......