2 Stroke Cylinder Maps - Making A Cylinder Map

2 Stroke Cylinder Mapping - Part 1

Primer - Part 2 - Part 3 - Part 4 - Part 5 - Part 6

Making A Port Map

Armed with only a piece of paper, a pencil and a piece of tape I'll reveal this engines ports in a matter of minutes.

Start with a piece of fairly stiff paper. It needs to be only a little taller than the liner.

Tape it in place inside the cylinder. It should fit tight against the bore. Make marks to indicate the top and bottom of the liner.

Using the edge of a pencil, rub it against the transfer port walls. The dark port outline will soon be easy to see.

The exhaust port becomes easy to see. You'll find the right amount of tension with the pencil to get an outline like this.

The intake port reveals itself. Usually its necessary to work the pencil from the top and bottom to get good results.

The port walls traced and easy to see. It will look like this when its done.

Take it out and lay it flat.

Tape it together so the marks are on the outside.

There is your basic port map. Even the most advanced porting software needs information like this to make accurate predictions. The next thing to do is to measure the area of the ports. When measuring the ports keep in mind the width of any bevel which might be on the port. Many times a transfer port bevel is .5 mm wide - that's .5 mm all the way around the port, so it is a good idea to subtract this from the measurement before you write it down - or whatever the actual bevel width is. This would be easier if the ports were flat, but they're not so we have to do it the hard way - transfer the real dimensions to graph paper.

To proceed to Part 2 - Measuring The Ports Correctly - Click Here.

Primer - Part 2 - Part 3 - Part 4 - Part 5 - Part 6

Armed with only a piece of paper, a pencil and a piece of tape I'll reveal this engines ports in a matter of minutes.
Start with a piece of fairly stiff paper. It needs to be only a little taller than the liner.	Tape it in place inside the cylinder. It should fit tight against the bore. Make marks to indicate the top and bottom of the liner.
Using the edge of a pencil, rub it against the transfer port walls. The dark port outline will soon be easy to see.	The exhaust port becomes easy to see. You'll find the right amount of tension with the pencil to get an outline like this.
The intake port reveals itself. Usually its necessary to work the pencil from the top and bottom to get good results.	The port walls traced and easy to see. It will look like this when its done.
Take it out and lay it flat.	Tape it together so the marks are on the outside.
There is your basic port map. Even the most advanced porting software needs information like this to make accurate predictions. The next thing to do is to measure the area of the ports. When measuring the ports keep in mind the width of any bevel which might be on the port. Many times a transfer port bevel is .5 mm wide - that's .5 mm all the way around the port, so it is a good idea to subtract this from the measurement before you write it down - or whatever the actual bevel width is. This would be easier if the ports were flat, but they're not so we have to do it the hard way - transfer the real dimensions to graph paper. To proceed to Part 2 - Measuring The Ports Correctly - Click Here.