Porting at Home

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...... under construction .........


If you've already read all the warnings about Port reshaping and you still want to give it a try, here's one way you can get started. This will help you with your Intake port and Exhaust port windows as well as the Transfer port paths (from case to combustion). We wont talk about shaping transfer port windows here; you're going to want to invest in rotary tools with angled attachments for those (moving up to the Big Leagues). This article is not a replacement for any of the tuning books and threads you should be reading when planning your new port job. This article serves to point out some of the hyper-critical things to consider and to give you some ideas of how to make it happen at home.


What you need
    - a plan (portmap - research, research, research)
    - steady bench or table
    - vice, clamps, or some means of securing the cylinder
    - good light (helps a lot if it's movable)
    - calipers (if you dont own a set already, stop reading now and grab some)
    - Dremel or other rotary tool
    - bits (a few sizes of each)
        - Carbide
        - High Speed Cutting
        - Abrasive
    - patience

Things to consider
How many times have we read about Crazy Wayne's time on the flow bench? (if you haven't, go read!)
Well, he's not that crazy.

    Angles
We're making an improvement here, we're not changing the way the cylinder works. You're going to want to preserve angles where they're present to retain the flow and Loop Scavenging characteristics of the cylinder. Put a big angle in the wrong place and you could be sending fresh mix where spent exhaust should be and visa-versa.

    Area vs Velocity
If you increase the area of a port window, you probably decrease the velocity of the gasses flowing through it. This depends on what the limiting factor of your setup is, but it's a good general rule. If you have an intake shooter (which has a specific angle and velocity) and you change the area of the window, you're most likely changing the flow/scavenging characteristics of the cylinder. Maybe certain ports should be incremented very slowly or left alone all together. (at least the transfers fall into this category for now)

    Cylinder Material
Most cylinders are aluminum with a nicasil coating or cast iron. Aluminum cuts easy as pie, but if you're dremeling away at high RPM it likes to clog up the teeth on your bit. Also, the nicasil is extremely brittle and chips very easily. You can get away with using a fine abrasive bit on the nicasil, but many people prefer hand files for that work. Iron usually cuts a little slower, but it's not as temperamental.


...... under construction .........