I have a Vitality 50cc 4 stroke . My Vitality would top out at 32mph and it would take a while to get there. Keep in mind I am at 6000 feet in altitude which may explain why I do not need to change any jetting. For those at sea level, you may need to go one fatter. Simple to do and should take no more than 15-20 mins to jet one fatter. Anyway.. I have finished installing my power up big bore kit and can now hit 42-44 mph and have gobs more torque. Again.. Keep in mind, I am at 6000 feet Bone Stocke scooter, and any where I go is up from here. Taking a scooter or dirt bike to over 12,000 feet is common for me. The general rule is 4 percent power loss for every 1000 feet. Since we have little or no humidity here in Colorado, the racers equate us at 9000 feet where I am . So.. Doing a little math, that means.. Typically I am down 36 percent in horse power as compared with those of you at lower altitudes. So.. I can do 42 mph up here which is pretty darn good for being down almost 40 percent in HP. Before, I could only hit 32 mph and it would take a while.. I can only imagine what kind of power I would have at sea level.. That would feel like a shot of NOS to me I am sure.. The Power up kit or big bore kit I used was the typical 139QMB big bore kit . It was easy to install as you can see in the Video. My 4 Stroke will now run with the stocker 2 strokes, and it is not broken it yet. So..It will get a lot faster with time.. A lot faster !! . So.. For those of you interested in powering up your 4 stroke for less than 100 bucks.. Check out my video. !! And.. Enjoy the ride...
