The port map of a cylinder is the size, shape, and location of the various ports, including the intake port, exhaust port, transfer ports, and boost ports. A literal port map is a visual depiction of this layout, often one that is to scale and includes measurements of the various ports and their locations. Typically the height and width of ports are depicted ("up" being in the direction of the cylinder head"), as well as their distance from the 'top' of the cylinder.
Making your own port map
A port map can be made by
- Cutting a piece of paper to exactly the 'height' of the cylinder, and
- Then gluing that piece of paper flat in the cylinder so that the top edge of the paper is flush with the top edge of the cylinder. A little bit of Elmer's, or other school glue is ideal for this application.
- After the glue has dried, you then use a crayon to make a rubbing of the inside of the cylinder, taking special care to make sure the edges of the ports are showing up clearly and sharply. If you push too hard with your crayon into a port, you will tear the paper, so don't do that. Just be careful.
- The next step is to carefully remove the paper without tearing it. The glue will rub off of your cylinder easily, so just take a second to do that. If it's being really stubborn, scrape it with your fingernail. You're not going to scratch the metal.
- Lastly, use a ruler to measure the sizes of the ports, and their distance from the top edge of the paper. Use metric measurements. Then you're done! Just be sure to write on your port map what cylinder the port map is depicting, and share it with your friends, or upload it to the wiki!
Examples of port maps can be seen on the following pages:
- Puch cylinder kit summary
- Motobecane port database
- Port map thread
- A55 Port Map Thread
- Peugeot Port Map Thread
Are you a visual learner? This blog post has an in-depth port mapping writeup with photos, and bonus! It even talks about modifying a stock port map too.