This is the third in a series of reports intended to document the results of progressive modifications to the LS650 engine.
 
Part 1 outlined the project, set the rules, and established the baseline performance values for a box-stock LS650.  You can find Part 1 here.

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1620523526

Part 2 examined the airbox.  We improved performance dramatically with a few simple and inexpensive modifications.  It was a lot of bang for the bucks.  You can find Part 2 here.

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1621150483

Part 3 takes a hard look at the exhaust system.  The airbox mods allow a lot more air into the engine, now we have to make it easier for the combustion products to get out of the engine.  In Part 2, we discussed how engine output is largely dependent on the amount of air that can fill the cylinder.  More air pretty much equals more power (as long as you add the correct amount of fuel).  It’s easy to add more fuel, but hard to add more air.

If the exhaust system isn’t up to the job, combustion products will be left behind.  Those spent gasses take up room and prevent air from completely filling the cylinder.  There will also be pumping losses associated with a restrictive exhaust system.  As the piston rises on the exhaust stroke, a restrictive exhaust system results in higher cylinder pressure.  The piston has to pump against the residual pressure.  It’s a parasitic loss we could do without.

So, we want an efficient free-flowing exhaust system to get all of the combustion products out of the engine as quickly as possible.  Seems to me that the logical place to start is the muffler.
 
What I am about to describe worked good for me.  If you decide to try this stuff on your own, you assume responsibility for the outcome.  If you don’t have the skills, don’t do it.  If you don’t understand something, STOP and get help.  Get a manual.  Read up.  Comply with ALL the safety requirements outlined in the manual.  Make sure you know what you are doing before attempting any of this stuff.

Let’s get started.

This is how I know it has a catalyst.

But alas, it’s not that simple.  There’s a kink in the plan.  The adapter requires a kink, because the stock header is angled inward toward the centerline of the motorcycle.

I’ve tried to bend these adapters.  It’s very hard to do.  There’s another way.  Cut the adapter half-way through, bend it, then braze it.  It’s easy.
 
The adapters are aluminized.  The aluminum must be removed in the area you intend to braze.  See the aluminum on the grinding stone.  For this job, stones don’t work.  They load up with aluminum.

Then slice through the adapter with a hack saw.  A muffler expander works great for holding the adapter.  Only cut half-way through.

Blunt the cutting tip of a small chisel.  This one is a ¼” chisel.

Use the muffler expander to hold the adapter.  Insert a short section of exhaust pipe in the other end.

This map gas torch works fine.  They’re cheap.  Most shade tree mechanics have one of these in their tool chest.