Hey from Montana. Got my kit (48cc grubee) put together on a Trek 800 mountain bike. Got a 2 questions. 1. Has any one tried a KMC z510hx bmx chain? It is rated at 2600 lbs tensile strength. 2. From 1/4 throttle to almost wot the engine four strokes. I junked the cns carb and replaced it with a speed carb. I have close to 50 miles on it. The c clip is in the middle of the needle valve. I was going to do a plug chop last time i rode it but the chain decided to chop (oem chain broke). Howerver, I did pull the plug and it is a nice brown color. The engine runs good at wot. Could the four stroking be caused by a weak spark and not a miss adjusted carb?