The pwk as11 is also known as pwm and looks like this
http://www.keihin-us.com/am/products/pwm.php
If you have it on a 300, consider yourself lucky believe it or not, it adds punch and as jakobi says, get it oval bored to 39 mm or get your squish corrected and it has plenty of top end, infact if your in the us, get the rb head mod before you do anything as its the cheapest mod and it will prolly be enough unless you ride desert long haul only!