Honda FOURTRAX RANCHER 2019 Owner's Manual page 208

Appearance Care
Exhaust Pipe and Muffler Maintenance
Refer to Safety Precautions on page 113.
The exhaust pipe and muffler are stainless steel but may become
stained by mud or dust.
To remove mud or dust, use a wet sponge and a liquid kitchen
abrasive, then rinse well with clean water. Dry with chamois or a soft
towel.
If necessary, remove heat stains by using a commercially available
fine texture compound. Then rinse by the same manner as removing
mud or dust.
198 Servicing Your Honda