196cc HONDA Clone mod question/issues

[Anthony S.]

Hi everyone. (I will have pictures/videos up as soon as I get them off my phone to my computer) Ok, so I got a Coleman CT200U minibike and got from Gopowersports.com the 196cc clone stage 2 kit (196CS3PK) with the 6619 ACR billet flywheel, 6270 Billet Connecting Rod, 3910X Spark Plug, mod2 cam with 18lb valve springs, stage 3 side out header GPS-0010 with a added muffler (so I can go to california recorational parks) and a cold air intake filter kit. I also got the tillotson pk1-a carborator before it was replaced with the pl1-b. I don't have a piston compression tool to get the piston back into the cylinder so I took it all to a neighboring business that works on mainly motorcycles and he's good at it (first time with a minibike though lol), and he installed everything for me no charge (so I would like to not bother him too much about issues). It ran fine and a TON more power. I was expecting it to run a little rough because of the cam but it seems like the engine's kicking rather hard on ignition and kicks puffs of smoke out every exaust cycle as well as a studder with all throttle acceleration except full open throttle. The smoke looks dark in color but isn't oily and is leaving black soot at the end of the muffler. At first I thought it was too much fuel so I put the original carb back on and the kicking reduced but was still there and still studdering. With what little engine knowledge I have is telling me ignition timing. I did some road runs with it and in the end I think I've fouled the plug, the engine is REALLY hard to start now. Any one run into any of these issues before and have any advice?

PS:I live in California so the original carb in non adjustable