Originally Posted by kolomootro
you dont always get what you pay for,sometime you get less.lol
i see that you are right about the engines,but i doubt there is that much of a difference between them right?
its not like one can go alot faster right?
no the china 2 strokes are all the same basic design, but some may have a few internal differences that don't make any performance differences.
it all dpends on what you mean by "fast".
you can greatly alter the speed of any bike just by changing the rear sprocket.
I bigger sprocket will give you more low end (for climbing hills) but not much top end speed. a smaller rear sprocket will give you more top end, but you will lose low end torque.
you can make a weak engine on any bike go 50 mph with the right gearing..but getting to 50 mph might take a long time.
do you want all out top speed with no concern on how long it takes you to reach that top speed?
or do you want your bike to accelerate quickly and top out really soon?
normally the stock rear sprocket that comes with these engine kits is a 44 tooth (which is geared to go on a 26" wheel). you can drop to a 41 tooth and get a tiny bit more top speed. you can drop to a 36 tooth and get quite a bit more top speed (but again, the low end torque at take off will suffer).
now, wheel and tire size also has a lot to do with speed (beacuse the wheel and tire diameter, will affect the gear ratio). a taller wheel and tire will give more top end, while a shorter wheel and tire will give more bottom end.
for example, On my oc.c. chopper the rear wheel is 20" but the tire is 24" tall. (tops out at @ 32 mph)
now, the same set up with a 21" tall tire will actually be slower on the top end.
it can get confusing, but changing the gearing, wheel size and tire size is the easiest way to make a bike fast or quick. there is a difference between fast and quick. a fast bike has lots of top end speed, but it may take a mile or 2 for it to reach that top speed. a quick bike has explosive acceleration and gets from 0 to whatever the top speed is, very quickly, but the top end speed won't be as fast as you might want it to be.