I bought a Jonway Y250T as a project bike. I have WHITE Spark, GOOD Starter, and good gas, but STILL it won't start. I replaced CDI, coil & Stator, battery and spark plug. I rebuilt the Carburetor and head.I got it to start, but the Idle was rough and white smoke poured from the exhaust. I noticed the flange the carburetor was connected to had a broken broken bolt so I extracted the bolt, resealed the flange, now it won't start at all. Tried adjusting Carburetor air/flow mixture. After about the fourth cranking cycle I hear the Carburetor cough a bit, but that's it. Any suggestions?
I removed the timing port screw on the side of right side of the engine, made sure the the cylinder was dead top and the lined up with the mark inside the engine. Outside of doing that, I don't don't know any other way to check for perfect timing.