Like the rest of your motorcycle, the external surface of the exhaust system should be periodically cleaned using an approved detergent (safe for use on your vehicle). If the motorcycle has recently been running do not wash or touch the exhaust system until it fully cooled. Remove any mud or insects from the header pipe with a stiff brush and detergent. You can remove and touch up any surface rust using a wire brush and a can of high temperature paint that is approved for use on exhaust pipes.
Muffler
Most US model KLRs are fitted with a spark arrestor that requires periodic cleaning. By cleaning it you can keep your exhaust system running more freely and get better performance from your motorcycle. Here is how to do it.
Tap the muffler from all sides with a plastic or rubber mallet.
Later models have three drain plugs while earlier models have two, plus there’s a removable spark arrestor on the later models. The basic theory is the same – we want to free the system of any excess carbon deposits.
Remove the drain plugs from the bottom of the muffler.
Remove the spark arrestor mounting screw (late models) and remove the spark arrestor.
Roll the motorcycle outside and with the engine in neutral start it up. Once the choke is no longer needed and the engine has reached operating temperature rev it up several times. Tap all sides of the muffler again with a plastic or rubber mallet and rev the motor some more to loosen any carbon from the system. You should see carbon particles falling on the ground.
Repeat this procedure until no more carbon can be extracted from the system.
Clean the spark arrestor (late models) with a wire brush. If you have access to a parts washer you can get it even cleaner.
Turn the engine off and let the exhaust system cool until it is safe to touch.
Reinstall and tighten the drain bolts securely.
Reinstall the spark arrestor (late models) and tighten the spark arrestor mounting screw securely.