Re: Standard Horepower?
A well designed expansion chamber will give better top end, an off the shelf expansion chamber is more likely to give better low to mid.
Real HP increase is through revs, HP = torque x revs.
Increasing compression and cleaning the ports will give better torque, getting the max torque at higher revs is through port timing, with sacrifice to low end torque.
Getting a well designed pipe that works at desired revs will 'super charge' your motor.
But again sacrificing low down, and making motor 'peaky' which doesn't suit single speed.
A 'streetable' motor relies on low to mid range torque, it's hard to have both out of such a small motor.
Then ignition timing can also play a role.
But some of these cheaper motors are so far 'out' in port timing, this is one of there biggest 'hold ups' in my experience. A well set up motor even with a 'good' standard pipe, will still get you to 40 MPH.