Since there are so many people moding there engines with strait pipes but then someone brings up back pressure i am going to make a quick how to make a exhaust.. i got most of this information from Heymow.com
1.Make the pipe longer then you will think you need it then paint the pipe with normal paint.. Run the engine for a while untill the paint starts burning off. Then cut the pipe 1 inch away from were the paint is still on. This ensures your pipe isnt longer then it should be thus slowing the gasses down when they are leaving the pipe.
2. Make the inside of the pipe the same size as the exhaust port or a little larger. You dont want it smaller that will restrict flow and hurt performance..
3. The more bends in a pipe the slower the gasses will come out.... that should be a obvious one... in the bend one side will be crimped in a little(if you bent a pipe you know what im talking about) Which may hurt the exhaust gasses leaving.
Im probaly forgetting something so post below if you want.
EDIT:TO GET OFF THE TOPIC OF 2 STROKES NEEDING BACK PRESSURE THIS IS FOR 4 CYCLE MOTORS ONLY!
1.Make the pipe longer then you will think you need it then paint the pipe with normal paint.. Run the engine for a while untill the paint starts burning off. Then cut the pipe 1 inch away from were the paint is still on. This ensures your pipe isnt longer then it should be thus slowing the gasses down when they are leaving the pipe.
2. Make the inside of the pipe the same size as the exhaust port or a little larger. You dont want it smaller that will restrict flow and hurt performance..
3. The more bends in a pipe the slower the gasses will come out.... that should be a obvious one... in the bend one side will be crimped in a little(if you bent a pipe you know what im talking about) Which may hurt the exhaust gasses leaving.
Im probaly forgetting something so post below if you want.
EDIT:TO GET OFF THE TOPIC OF 2 STROKES NEEDING BACK PRESSURE THIS IS FOR 4 CYCLE MOTORS ONLY!