Rowdy's Motorcycle Blog: Buell Exhaust Repair

About two weeks ago, I thought I heard an exhaust leak around the lower front port side of my Buell Cyclone. (I'm using the navel term port here - in this case meaning the left side of the motorcycle from the perspective of a rider sitting normally on the bike.) I also noticed that the bike started to sound more like a Sportster. Heheh, go figure. When I investigated, I noticed what looked like a crack in my exhaust where a mounting bracket was attached to the exhaust pipe going into the muffler.

I think what happened was a stress fracture formed along the outer edge of one of the welds holding the bracket to the exhaust pipe. After that, the vibration of the engine simply caused the crack to spread. Then, at some point, the other weld was supporting more weight than it was originally and formed it's own stress fracture which grew in a similar manner. The edges of the weld are a natural place for this to happen, as the wall of the exhaust pipe is much thinner than the weld itself.

The weekend after discovering this, I pulled off the muffler to weld up the cracks. When I unbolted the front mounting bracket, it simply fell loose to the ground. The cracks had spread all the way around the original welds. Two holes were left on the pipe where the mount once was.

Fitting the bracket back in place was quite simple. When I put the bracket back in place, there were no large gaps, and gravity simply held it in place while I added a couple tack welds. I almost used no filler rod at all - I simply melted some of the excess metal from the weld beads and flowed it into the puddle I had formed along the crack.

Here, you can see where I stopped part way to show how I was using the existing weld material to fill in the crack.

Here's a pic from pretty much the same perspective after completing the welding on this side.

I also noticed a few stray cracks in the pipe leading away from the welds. I wonder if those were originally there, or if the thermal stress from welding caused them. I simply went over those with my torch to weld the cracks closed. After letting everything cool, I grabbed the bracket and tried to move it back and forth to see if there were any obvious weak points in my welds. Nothing broke apart, but I did see a very large crack in the bracket itself where it mounts to the frame. I simply went over that crack as well, welding on both sides of the crack.

Here's an example of where I welded up a stray crack.

Well, I think this should hold up. After riding around a bit to see that it stays together, I should probably paint it, since there's a lot of exposed ungalvanized steel there now. Below are some more pics at different stages of the repair process.