Build a "Tuned" pipe for a 2-stroke

Step 8: Making the pipe FIT.

Whatever machine you are building this for, its very unlikely that the port comes out of the engine in a way that will allow you a straight shot out to put your pipe on... which means we have to do a bunch more cutting and welding.  We have to "curve" the pipe around both to avoid obstacles AND to make it shorter- 'cause you really don't want 3 feet of pipe sticking out behind your bike!  There are two ways to do this- the easy way, and the hard way.

The HARD way (Pictures 2-5)

This is the way that was shown in A. Grahm Bell's book... And it's HARD.  Requires a lot of thinking, planning, and way more welding.  Goes like this:

1.  Decide where you want the "bend" in the pipe.
2.  Cut the pipe straight through.
3.  On one side, starting at the widest point of the circle (the diameter) in the direction you want the pipe to bend, cut off a sliver at the angle you want the pipe to go.  See Picture 2.
4.  Weld the sliver back on to the same piece of pipe, just on the opposite side.  See Picture 3.
5.  Weld the other half of the pipe to the first half.  See Picture 4 & 5.
6.  Repeat for every bend...

As you can see, its very hard to get everything to line up nicely.  I did the entire first cone this way, and was not pleased with the results.  I ended up building a new first cone, and used the easy way on it.  I feel it turned out MUCH nicer- and while it is more angular it was so much simpler to do. 

The EASY way (Pictures 6-11)

Lots less cutting and welding.

1.  Decide where pipe is to be bent and at what angle (Picture 7)
2.  Divide angle in half (angle as measured from the centerline of the pipe, see Picture 8), cut pipe in direction you want it bent at half of the desired angle.
3.  Rotate one of the cut halves of pipe 180 degrees, weld together (Pictures 10-12). 


There are programs out there and if you enjoy math, you could sit down before you started building and figure out all of the angles for the cones and have done it in one fell swoop- basically eliminating this whole step.  I don't enjoy math that much, and since this is a one-off project, it was easier to build the pipe, then cut and fit like this. Just keep cutting, welding, and test fitting (Pictures 13-15) to the bike as you go to make sure the pipe is going the direction you want it to go.  My pipe came out better than I had hoped, but I do still think it could have been a lot better as far as fitting to the bike goes.  Hey, its only my 2nd attempt, can't complain too much!

You can see in Pictures 16-29 How the pipe turned out.  After I had experimented with both methods of bending the pipe, I went back and re-did the first cone of the pipe using the "easy" method, and it turned out much better.