2021 Harley-Davidson FLHXS Street Glide Special — Maintenance & Ownership Guide
Routine Maintenance
Key maintenance tasks to keep your 2021 Harley-Davidson FLHXS Street Glide Special running reliably.
Oil and Filter
Requires 5.2 quarts of 20W-50 oil. Standard intervals are 1,000 miles for the first service, then every 5,000 miles.
Clutch Adjustment
The 2021 model uses a cable clutch which requires periodic manual adjustment at the lever and the primary, unlike the previous hydraulic versions.
Air Filter
Features the high-performance Ventilator air cleaner with a washable filter element.
Common Wear Items
Parts that wear over time on the 2021 Harley-Davidson FLHXS Street Glide Special and should be inspected regularly.
Brake Pads
Heavy touring bike (800+ lbs) tends to wear front pads quickly, especially if RDRS linked braking is used frequently.
Tires
Rear tires (Dunlop D407T) typically last 8,000-12,000 miles depending on load and riding style; front (D408F) often lasts longer but can develop cupping.
Popular Upgrades
The most popular aftermarket upgrades for the 2021 Harley-Davidson FLHXS Street Glide Special.
Exhaust
Slip-on mufflers are the most common upgrade to improve the V-Twin sound and reduce heat from the catalytic converter.
Suspension
While the Special has 'premium' shocks, the 2-inch travel is limited; many owners upgrade to 13-inch aftermarket shocks for better ride quality.
Handlebars
Owners often swap the stock bars for 'Ape Hangers' (10-14 inch) to improve ergonomics and long-distance comfort.
Common Replacement Parts
Parts that commonly need replacing on the 2021 Harley-Davidson FLHXS Street Glide Special.
Shift Linkage
The OEM shift linkage is a common failure point on Harley touring models; many owners upgrade to a more robust aftermarket unit with heim joints.
Battery
High-compression 114 engine and extensive electronics put high demand on the battery; typical lifespan is 3-4 years.
Used Buying Inspection Checklist
What to look for when buying a used 2021 Harley-Davidson FLHXS Street Glide Special.
Infotainment Screen
Check for 'ghost touches' or delamination on the GTS screen, which can be expensive to replace.
Oil Leaks
Inspect the bottom of the primary and transmission cases. While later M8s are reliable, early 114s can occasionally show signs of 'sumping' or fluid transfer.
Service History
Verify the 1,000-mile break-in service was performed by a certified technician to ensure warranty compliance and proper engine seating.
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