De-carbonizing is a great way to restore power.
Removing carbon build up in the combustion chamber means you can get more bang from you gas.
Removing carbon build up in the muffler can increase outflow and restore that torque to climb hills.

Combustion Chamber:
This is inside the head, do not take off the head unless you have a new head gasket.
Start by removing both rear frame covers.
Remove the spark plug cap and ignition coil.
Loosen the air cleaner connecting band and remove the air cleaner case.
Remove the rear shock absorber lower bolt.
Remove the spark plug and fan cover.
While your here check spark plug for carbon build up or general fouling also check for proper gapping
Remove the cylinder head shroud mounting bolt and remove the shroud.
Remove the four cylinder head attaching bolts and remove the cylinder head.
*Actual Decarbonization*
Remove the carbon deposits with a steel brush but avoid damaging the combustion chamber wall and gasket surfaces.
Clean the head gasket surface of any gasket material.
Remove carbon deposits from the piston head.
While its open you should check the cylinder head for warpage with a straight edge and a feeler gauge. Service Limit: 0.10mm (0.004 in)
Install a new cylinder head gasket
Install the cylinder head on the cylinder.
Install and tighten the four cylinder head bolts. TORQUE: 7-9 ft lbs
Install the cylinder head shroud and fan cover.
Install the spark plug
Install the rear shock absorber lower mount bolt.
Install the air cleaner case and tighten the air cleaner connecting band.
After assembly is complete. Perfrom a compression test.
Check for any abnormal engine noise or air leakage past the cylinder.
Install both rear frame covers.

If anyone has any information on how to de-carbon the muffler email me