slow speed

Hi guys my motorized bike i bought a bunch of upgrades like the bbr thrust exhaust, performance carb with better air filter, new gas tank, new cylinder and cylinder head, and it keeps topping out at around 20mph im new to motorized bikes and just got this like a month ago and only been riding it...

Hi guys my motorized bike i bought a bunch of upgrades like the bbr thrust exhaust, performance carb with better air filter, new gas tank, new cylinder and cylinder head, and it keeps topping iut at around 20mph im new to motorized bikes and just got this like a month ago and only been riding it...

So long story short bike got stolen but I got my racing carb and 36 tooth sprocket back. My old bike was super fast about 40mph ran perfect. Got a new kit about 2 weeks ago and just seems super slow I had the stock carb on until float got stuck and I just threw on the racing carb (no difference...

This is making me scratch my head help :/ How much is the max speed for a 2-stroke 66CC engine because mine will go only 6-7(km/h) or 4.3mph. Should I use the warrenty and tell the seller to get a new one? thanks,