Cold Starting Problem Piaggio Fly 100

Hello, my scooter is a Piaggio Fly 100 4T 2012 model. I had a problem with starting the engine when it was cold and it would stall if I didn't give it gas. I changed the fuel hoses, ignition coil, spark plug, spark plug cable, spark plug head, fuel tap, intake manifold hose, but it didn't fix it. I took it to a mechanic and he said there was a problem with the automatic choke and he fixed it. It seemed to get better for about 15-20 days, then it happened again. I disassembled the engine up to the crank, saw that the cylinder and piston were broken, and found that the valves were covered in soot and were leaking. Clutch, variator rollers, crank seals, crank bears, clutch belt, brand new cylinder, piston rings were changed, the soot on the top cover was cleaned, we bought new valves, got used to them, and tidied them up, and the engine stalled again when it was cold. Just after waiting 20-30 seconds at red light, when i give throttle it little shakes for a second and it goes. No other problems with hot engine.

 

Greetings mate, the problems you have listed would all hint towards carburetor related issues, ,my advice is to inspect the fueling system more thoroughly so that means inspecting your fuel filter in case it has clogged as those like to get dirty them bastards, take apart your carb and give it a thorough clean and i mean thorough as you know carbs especially like to hinder the performance of your scooter when dirty,after that install it and test if it has a problem cold starting,if the issue still persists you will need to tune your carb, but in order to do that you need to get your engine started one way or another and warm it up to operating temperature for more accurate readings, after you have warmed it up you need to locate your adjustment screws and after you do that its all about playing with it and keeping a close eye what works best and gets your scoot started the fastest, first play a little with your idle and maybe increase just by a little bit to prevent it from stalling and turning off,after that locate your air-fuel mixture screw, clockwise or inward to richen it,counter-clockwise or outward to lean it out,i have had the same issue and a simple carb clean and tune made it start up in the coldest conditions with no problem when before it could barely start and would not idle for more than 10 seconds, but once you feel like you have tuned it enough,next time you ride your scoot monitor how it performs and tune accordingly