My KLR actually had plugs on the factory silencer to clean out...
The book even says:
"Spark Arrestor - Clean Every 5,000Km (3,000mi)"
Remove the drain plugs on the muffler (3 of them)
(theres a picture)
In an area away from combustible materials, start the engine with the transmission in neutral
Raise and lower engine speed while tapping on the muffler with a rubber mallet until carbon particles are purged from the muffler.
Stop the engine
Install the drain plugs.
I **** you NOT! this is a true story...
Maybe that's why the clutch didnt gum up ???