Thread: 140cc engine cutting out help???

ok i am new here, but have been into hondas for years. i just bought a 140cc lifan for my ct70. it starts up fine, idles fine but when i am going down the street and i hit the throttle it seems to die then i let off the gas and hit it again and it goes. what am i doing wrong? dont know if i need a carb adjustment? i changed the spark plug and it still does it. i changed the exhaust system and it still does it, i am getting fuel to the carb and its flowing very well! dont know why i am not running right??? please any help would be appreciated

what air filter are you using?new?used?the air filter needs to be in place and be unrestricted,preferably a new high flow.i had a problem like yours until i put a new k&n style filter on.

it the new filter that came with the engine! i tried a few things and i went for a ride. in 2nd gear at 1/4 throttle it died and i let off the gas hit it agian and it went. i dont know whats up. its a new motor. i bought a differnt 125 motor and put it on my z50 and i havent had one problem with it.

assuming you tried adjusting the jet needle in the throttle slide to a richer position ( moving th c-clip down ) and or changing the main jet to a larger size ! ...my oppinion... sounds like your carb may be too small... or your floats are out of adjustment. my reasoning... i'd bet that your emptying the fuel reservoir in the carb/float bowl, faster than the needle jet can keep up filling it, when you punch it and when you let off its filling back up. try adjusting the floats to aloow fuell to enter the bowl at a faster rate!

how wold i adjust the floats?? sounds like it is running out of gas and then filling up again. how do i fix that? and the carb is a 26mm mikuni came with the engine and its really big dont think i need one larger???

turn the carb up side down on your work bench, take the bowl off , at the end of the floats, where they pivot. you will see a small tab approx 1/4" x 1/4" with a piece of wire looped over it and attached to the wire is your needle jet. it's the valve that actually lets gas into the carb when the floats float down and shuts off gas to the carb when the floats float up. with the carb upside down, slightly prying that tab up will let more gas into the carb as the carb empties. you need to make SLIGHT adjustments until you get it right. because if you bend the tab up too much the needle jet wont close when the floats float back up, wich will cause the carb to overfill and dump gas out of the overflow hose!

cool thanks man i will give it a go today! thanks for all the help guys,

i like the thumb throttle!!! find yourself a k1 or newer front end the ride is soooo much better!!

the carb ended up getting replaced with a real mikuni carb, and that was the problem. The carb that i got with the engine sucked.