To keep my engine running i have to pull the throttle obviously to rev it, else it the engine cuts out, and when i ride it splutters and cuts out, so i kick down a gear n it starts again but then dies again.

replace the fuel pump or adjust the TPS. It doesnt do it in nuetral its because it is not under a load. Put in dealer mode to check the TPS. It should read -COO... If the - is not in the middle (if its up top or on bottom) it needs to be adjusted.

Look for air leaks on the inlet manifold/carb plate. If any air can leak in here, the motor runs lean and rough. Since you replaced the carby, double check the rubber parts for leaks (may not be obvious off the bike so stretch it a bit) and make sure the gasket to the engine is OK (some bikes use o-rings which shrink over time). Next time you run it, when it starts acting up, reach down and pull/push the carby towards the engine. ANY change in revs or running indicates a leak.

My 05 1.6 renault megane struggles to start in th morning and once it does fire up you hav to rev it to ensure it wont cut out. The car then splutters and judders a bit till its warm then it tend to run ok. but keeps on switching off at the robots when i stop please what could it be

best bet is to go get any codes that may be stored in the PCM. This will take alot of the guess work out of diagnosing it. Or remove the spark plgs and replace them.. If you have 50,000 or more this could be the cause but a code may tell you which one is the issue

Check that there is some free play in the throttle. When you twist the grip the first bit of movement should only be taking the slack out of the cable, in other words, you need about 1/16th of a turn of the grip before the throttle is actuated.
Also make sure the cable is routed properly - and check for any air leakage between the carburetor and the engine. With the engine running, if you spray WD-40 around the inlet manifold and it causes the idle speed to change, then there's an air leak.

idle screw by sounds off it buddy on the carb will be the idle screw turn this in till it idles at 1000rpm on rev ometre get back to me if its injection

Seaform will fix this trust me...go to autozone oickup a can put in 1/3 of can into approx two gallons off gas and ride at least fifteen miles hard and it will run alittle rough at first but it should kick in while you ride.

mate adjust the mixture screw on the carb to its correct setting in the manual and put the idle screw in a bit so the revs rise a tad good luck

is the check engine light on ? find dle air valve mounted on throttle body ,remove an clean with spray carb cleaner , or look for vacum leak.

my pit bike will not keep it revs for a long time so can some one help me it is my first pit bike