Hi there Guys, Im new to the game and i need advice on porting heads. I am practising on a old 72' Honda motorcycle cb350 Racer. I have rebuilt the engine myself and have gotten it from 30 BHP to 47 BHP.

Its a lot of fun doing it and i know its not a huge jump in power but please remember its my first engine experiment and ive done all the work in my college workshop after hours (very nice Teacher is a petrol head and lets me stay on) I have been told that Hot rod guy's in the States are the best people to go to to ask advice on porting engines so here are the Question's i have.

Does the Exhaust port need to be opened?

Why Does it need to be opened?

Should i leave the port with a rough finish? (i have used 60 grade grit brush on inlet)

I hope someone can help me out here, any advice would be excellent!!  

first off dont sell yourself short, that is about a 46% increase in h.p.the answer is yes.an engine is like an airpump,(more in/more out).the finish on the exhaust can be smoother than intake,but not real important.good luck!