I have some miles on the Raw 50cc and it is hands down smoother than the Grubee 66cc but it alot less pulling power. I cleaned up and matched all the ports, trimmed the head, and opened up the tranfer ports because the sleeve had them almost half way closed off. I probably have a 100 miles on it and I haven't even had to tighten a single fastner. On the Grubee I had to stop and retighten something during almost every ride. I'm not slamming Grubee, they have a very good kit but the vibration on the Grubee is something I'm not going to deal with if I don't have to.
Now I'm curious if the vibration is due to the displacement or the brand. My theory was that they just put a bigger piston the the 50cc bottom end and for whatever reason caused the heavy vibration I am experiencing. Maybe I just got a bad one or like one of the threads said the timing is the cause of the issue. I wonder if an offset key from a snowmobile could be made to fit?