I've just bought a new Montesa 314r and it runs well but the throttle response isn't great from tick over and fuel drips from the carburetor overflow pipe which is emptying the fuel tank quickly so I'm guessing I need to adjust the mixture screw and check the floats but I don't know where the mixture screw is and what the standard settings are? Any advice is appreciated. Thanks

I think the main problem you have is the float... Id recommend taking the carburetor off the bike...dissasembly, clean and pressure clear all the tiny holes on it... then reassembly checking everything is OK.... pay major attention on the float needle... if its an old bike might not seal due to worn rubber cone seal... ifthe bikes been stored for a long time... before assembling the carb into the bike again, clean fuel tank and clean or replace fuel hoses and fuel filter (if any)....

The simptom youre describing tells me the bike is running rich.... Thry the described above and cleaning/replacing the air filter (a low airflow from the air filter may result in the bike running rich also)

as above.never ever try bending float to stop leaking.thats not the problem.float needle not seating is the problem.adjusting air screw wont help either.only adjust after bike running correctly,about 1 and half to 2 turns,after feeling screw going home lightly.

Sorry for the slow reply, i took the carb apart and it was clean and the floats and needle worked well, i tried adjusting the air screw but i cant find a setting that creates a good mixture as the spark plug is always slightly wet with fuel, i cleaned the air filter when i took off the carb im guessing the further out the air screw the leaner the mix? thanks