GT2 vs GT5 pros cons? 66-48

one more question. overall quality from case, screws and details like the clutch arm - how are they compared?

the case itself looks almost identical from the outside i havent split my new engine she runs to good but the weld on the clutch arm is better on my new one and they use flat philips combo head screws which is nice so you dont strip them as easy old ones where just philips and where soft so had to be very careful not to over tighten them

i have the gt5. 2009 model..had it for a bit over a year now.

ive noticed a problem with mine..the cylinder head doesnt seem to seal properly...i have oil and gas all over my cylinder and cylinder head...the studs and acorn nuts are so tight that i accidentally turned them into bolts.

my spark plug blew out while i was riding..helicoil fixed that right up..but it still doesnt wanna run and gas and oil are still all over the cylinder head. cylinder is scored but still has pretty good compression and runs ok whenever it feels like it.

I've become a fan of Flying Horse. Just like all kit motors, they need to be checked over before installation, but I think they're slightly better quality overal, which isn't saying much lol.

Flying Horse motors are built with Japanese bearings, which that alone is a big step up. They also have lighter piston assemblies. My newest is the smoothest motor (china girl) I've had yet.

I have about 900 miles on it now with no mechanical problems.

My GT5-a has had no problem, neither has either of my GT5's. The main difference between the 48cc and 66cc is power, however they use the same crank (actually the whole bottom end is the same to my knowledge). As far as I can tell, the crank is balanced for the 48cc, so the heavier 66cc piston actually unbalances it. These motors are vibration governed meaning the 48cc then logically has a higher top speed, the question of if it has the power to reach that speed is an entirely different one (a strong gust of wind will take my 66cc from 56kph to 45kph easily). this can be solved with simple mods, everything from porting to aftermarket parts will net you a big gain, however a 66cc crank can be balanced by cutting the piston or drilling the crank (check out crank balancing in the high performance forum). So AFTER the modifications, the 66cc would have more power. there is no replacement for displacement.