i was just wondering how it was done and how much they take off on a 4 stroke

john

 

match up your gaskets with the metal, take a magic marker and trace the hole, it sould be bigger than the ports. grind to the outside of the line. you sould feel the engine run much smoother because you got rid of all the imperfections. be careful not to take off to much metal because if it is a liquid cooled machine you can ruin the water jackets. i would practice on a lawn mower engine untill you get the hang of it.

 

I did on my 400ex. It was the first time I tried. I just matched up the intake and exhausts and widened them very little. The important part is to match the diameter of the intake piece to the engine perfectly. You will see what I am talking about when you get there. Also, leave the intake side rough to help atomize the fuel.

 

does it make much of a differenct in power

 

just a word of caution, be very, VERY, carefull!

It's much easier to lose power and/or ruin a head than it is to gain power.

Not trying to talk you out of it, just be carefull, it's much easier to grind metal off, than to glue the little pieces back on

Leo