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Pipe Dreams: the, uh, pipe

August 2, 2007

Okay, you’re done with the easy part. Now comes the hard part.

Rejetting the carburetor, as I did in the previous post, is necessary because the Sito Plus pipe is less restrictive than the stock piece. Installing it will help the engine breathe better, but the increased volume of air will result in a leaner fuel/air mixture. Leaner means hotter (by the same token, richer means cooler). When air-cooled 2-stroke engines get too hot, they seize… the piston expands, and so does the cylinder barrel. Not a good thing to have happen, especially on a freeway or major highway at high speed.

Sito Plus pipe

This is a Sito Plus pipe

Let’s get started! First order of bidness is to lift and support the rear of the bike. You’ll need to remove the 17mm bolt that attaches the pipe to the rear suspension arm. Yes, you could deflate the rear tire, but since you know how to remove it, why not do that? More room to work that way.

The exhaust pipe is held on to the engine side with a 13mm nut and bolt on a clamp. Just loosen this, it won’t come off anyway. I loosened this before taking the bolt off the suspension arm.

You will probably discover that you can’t separate the pipe from the engine with your hand. Many, many, many cycles of heat-cool won’t weld the pipe, but will make for a very tight fit at the exhaust port. That’s why you need the tools below.

Tie rod end separator and 3-lb. hammer

The one on the left is commonly used for separating tie-rod ends from steering arms. I just happened to have it, but anything with a long, heavy metal shaft will do. Take said metal shaft and place one end in the center of the elbow formed by the pipe as it leads into the muffler. Tap, don’t whack, the other end with the hammer, which is a 3-pounder. After a few taps, the pipe will fall on the ground.

The 17mm bolt and its accompanying washer and lock washer were kind of ooky, as was the underside of the floorboard, so I took the opportunity to clean them. Ditto for the back side of the engine, which was covered in a thick layer of oily schmutz. I squirted a whole bunch of Simple Green on this mess, and hit it with the high-pressure nozzle.

I was amazed to discover the suspension arm was silver-gray, and not black.

Once again, installation is the reverse of removal. Because you may have to muscle the end of the pipe in order to line it up with the engine’s exhaust port, it’s best to first install the 17mm bolt (with lock washer and washer, respectively) loosely. Notice that there’s a threaded receptacle on the forward bracket; make sure the bolt can thread into it.

Go to the other side, grab the pipe and push that sucker on (remember to loosen the 13mm nut first). You probably won’t get it on all the way with your hands, so get a piece of 2×4, place it below the elbow, and tap it with the hammer. If you hit the pipe with the hammer, you’ll dent it, but the 2×4 is soft enough to absorb the impact. Again, tap it, don’t whack it. Once the pipe is securely located, tighten the 13mm nut, then tighten the 17mm nut. Then put the rear wheel back on.

Having done all this, I was very careful to pick up all my tools and equipment and put them away before returning to the PX to start it. I turned on the fuel and pulled the choke, inserted the key and turned it to the “on” position, made sure the gearchange was in neutral, squeezed the clutch lever and hit the starter button. No, I didn’t kick it. So sue me.

It fired right up, and yeah, it was noisier than before. I needed to go back to Soundspeed Scooters to return the extra jets Joe had given me, so this would be a perfect opportunity to check my work. Favicon

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