My lads PW 50 is a terrible starter from cold. It takes dozens and dozens of kicks to get it started, but once warm it will start first kick every time until the next time you come to start it, anyone got any ideas, i'm wearing my foot out.

Welcome to the forum.
I'm going to assume you replaced the spark plug and checked / cleaned the air filter.
the things I can think of are: maybe the bike is in need of a fresh piston and rings . in need of a carb adjustment or jetting change. or the choke is not functioning properly. the carb could be gummed up enough to cause float problems , or you could just have a problem with your carb float or float needle not functioning properly and need replaced.
I'm sure there are other possibilities.
with my son's pw I just put the bike up on the center stand ( a must- the bike must have the rear wheel off the ground to start) turn the choke on , flip the switch to start and kick it three times and it fires up like a champ. So obviously if you are having to kick it fifty times it is in need of something .

How many hours/miles are on it? it could be low compression that is causing this too.

The Pilot jets on the PW's are tiny and clog easily. Clean it with Acetone and you should be back to happy land.

I have found that it helps to run a small amount of fuel additive like sea foam to prevent corrosion and varnish in minibikes.

:computer

Sorry for the late reply lets just say me and computers don't gel. Carb and fuel tank have being cleaned, just put new piston and rings in thinking it was low on compression but that never worked. Might try cleaning the little jet with acetone but it looked clear when I cleaned the carb. How can I tell if the float or float needle need changing.

:computer

Sorry for the late reply lets just say me and computers don't gel. Carb and fuel tank have being cleaned, just put new piston and rings in thinking it was low on compression but that never worked. Might try cleaning the little jet with acetone but it looked clear when I cleaned the carb. How can I tell if the float or float needle need changing.

I was using the float and float needle as and example of things that could be gummed up like bpro was saying it could be the pilot . the float would be full of fuel (cracked) or there would probably be fuel leaking out of the carb through one of the tubes if it were the float needle .
I hate to defer to another website Im not with it today
for float and float needle help
Read here :Carb Float Needle causing fuel leakage into the engine cases. (http://www.weeksmotorcycle.com/carb-float-needle.html)