The ability to successfully tune and build high performance engines is a science that takes years to develop with lots of failed parts along the way and tons of money spent.
Every system in the engine affects the other and the relationship must be symbiotic and well thought out.
A larger bore will just give you more torque but the ratio between the new bore and the combustion chamber changes and the compression ratio can become much higher, leading to detonation and a holed piston.
A larger displacement sucks more air and thus needs more fuel to meet the optimum fuel/ air ratio.
To expel the extra air, a better flowing exhaust is needed.
If the engine's rpm's are limited by the ECM then the bike may accelerate faster but the top speed will be the same.
The CVT, clutch and variator must work in harmony to give either faster acceleration OR top speed.
To do all of this correctly, a person really has to know what they are doing.
Any time you modify an engine to get more horsepower, torque and rpm's the life span will be shortened in most cases.
Race engines used in competition are sometimes rebuilt after every race due to the wear and abuse the engine goes through in the event.
If you want to look and sound cool, build that little 50cc scoot! I have:) If you want to actually have something that will run better, faster and longer, just buy something larger and leave it alone:)
Sam:)
