Agility 125 One fast one slow

[YumdeYum]

New member here. 

I just picked up two brand new 2012 Agility 125's.  Hoped on 1 and took it for a spin. Riding about 35 mph I opened up the throttle a bit more and it had a rattle or a different putter sound to it.  So I thought I would get on the other one just to see if it was normal. 

The other one felt like a 50 cc could barely get up to 35 mph.

I guess I don't really have any questions... Just dropped the slow one back off to the dealership.  Just seeing if anyone else had an experience like that?  Could the valve clearances cause this? Maybe throttle tension?

[tortoise]

In the context of preventative maintenance . . try adding around 2 ounces of Techron to the gas tank before refilling, to aid in clearing any carb internal fuel passageway obstructions, prior to every-other oil change.

[YumdeYum]

Thanks for the tip.