What are some of the do's and don'ts of porting and polishing 4-stroke heads. I have mine a part and did notice more casting flaws than I like. I would like to open the ports slightly and polish them up a bit. I was told the exhaust port could be polished as smooth as a babys behind but not the intake port?? Why is this?? Any suggestions or tips will be greatly appreciated. Thanks in advance.

 

If you polish the intake it will actually slow down the intake charge. It will also decrease turbulence and cause the air/fuel to not mix properly. Something you should consider, if you just clean the ports, you'll be fine. If you open them up without changing cams, you will dramatically lose lowend power. I had this happen when I ported a mojave for a friend and he ended up using stock cams.

 

AlkyBurninX is right. You need a rough texture to the intake for proper atomization of the mixture. I would remove any casting flaws but dont open the entire port itself. I haven't seen the particular head you have but usually the short side radius could use some improving. Basically let your fingers be your guide and if you feel a hinderance you can smooth the transition. Remove the metal slowoly and a little at a time and keep checking with your finger to determine if it is smooth. The exhaust port can be a lot smoother than the intake. Remember, if you polish the combustion chamber you will increase the size and reduce compression. There are plenty of sites out there to help. Ill try to post some links for you later. Good luck

Here is a good site for car heads. Most of the same principles apply;
http://cgi.ebay.com/ebaymotors/ws/eB...tem=1824870873

 

What do you think about something like barons torque masters? they are a ring shaped with about a half turn that fits betewwn the carb & the intake on street bikes, the idea is to swirl the fuel mix more, creating more torque..I wonder if it would help with a quad?

 

Thanks alot for the help guys. I really appreciate it.