if i put a power valve on my honda xlr 125 would it make my bike have faster acceleration
The powerband is caused by tuning an engine, they are most noticeable on a small lightweight 2-stroke. When you are riding and you change up too early you will have noticed the bike slows down and does not accelerate very well, but if you keep the rpms within a certain range it will accelerate smoothly – that is the effect of a powerband, it can be moved up or down the rev range by altering the ports and by changing the harmonics of the expansion chamber (the trumpet shape of the exhaust system). Either your garage is having a laugh at you or they are hopeless – I suspect the former. EDIT: You make it faster by tuning it –?making it less reliable and these bikes are already peaky. If you make them more peaky you will need to run them at higher revs –?higher revs = more power from available torque, therefore you do not want to move the powerband down the range or broaden it. Changing the sprockets will not improve acceleration AND top speed it is one or the other.
A power valve is a device that manufacturers fit to the cylinders of highly-tuned 2-stroke motors. It's purpose is to vary the timing of the exhaust by changing the height of the exhaust port(s). This is done in order to allow these motors to retain some bottom and midrange power. A Honda xlr is a 4-stroke so you cannot fit a power valve to it. The exhaust port in a 4-stroke is in the cyliner head, not the cylinder wall, and it's timing is controlled by a cam acting on a poppet valve.
Does not apply to 4 stroke motors.
