When it comes to porting, what do you do? Keep the walls of the ports 'rough', 'smooth' or 'polished' and why?
But why? Many people will say that getting the intake tract correct is more important than the exhaust. The main argument is that drawing air into a motor is far more difficult to do efficiently than pushing it out. Another question is, how rough is rough? Arguably the objective behind the port wall finish is to make it rough enough so it creates turbulence to prevent "fuel pooling" yet doesn't create turbulence to the point of creating "chaotic" airflow. I gave my sermon concerning ports on one of my web-pages so I'll spare everyone.
My thoughts exactly,all the work on the 350 head is on the intake side,this seems to work well,engine makes pretty decent power.
bead blaster/sand blaster rough.just matching every thing is a precaution .since every one doesnt have a flow bench to test you figure the factory did it pritty good and you just tinker a little bit.but there sre some bike you look at and say might do better if i did this and it works ,but bigger is not always better.my boss at phoenix cycle he rides the cbx they cut and welded and machined new ports(intake)cause he thought it would be better this way.wich it is.still makes 138hp and hes re did them again.so go figure you have to have an idea and think it through for a while just do go in and make yourself a bigger mess.
If you are using a good quality carb(mikuni) than fuel pooling will not occur because there is never a problem with the spraybar diffusing or atomizing the fuel with the air mixture. Mabey on a really cold engine, but that does not count. I spent 12 hours with 3 grits of fine sandpaper on my ports after they had been shaped and it flows like a freight train. Buff
That's pretty much where the argument arises... whether or not fuel remains atomized. Although a good carb can do a good job with atomizing fuel, the fuel doesn't necessarily remain that way. That's one reason why engine manufacturers went with the straight port design on performance engines. Although carbs can atomize fuel pretty well (fuel injection better still), they had no control over what happens further down the line in the ports. One advantage modern straight ports have is that they reduce the chances of fuel droplets from combining when colliding with each other due to a change of direction. Remember, not all fuel droplets are the same size. The difference in size means a difference in weight. The droplets don't all follow the same path when traveling through the ports so they tend to collide, especially when subjected to changes in direction. In addition, when it comes to straight ports, the reduction in how much the charge needs to be redirected reduces the chance for fuel to collide against the ports' outside radius wall, thereby reducing the chances of pooling. Although my argument is based on several SAE papers I've read, I'm sure there are plenty more that have 'proven' the contrary. Fun, huh?
engine manufacturers went with the straight port design well, you can either make air flow at high velocity OR you can make it go around a corner!
Hey Footwork and Diesel i found a new type of abrasive pads,that are very flexible and come in rough to fine grit,perfect for headwork.I will bring them with me,think you guys will be impressed.
