1990 Harley-Davidson Electra Glide Police FLHTP — Maintenance & Ownership Guide
Routine Maintenance
Key maintenance tasks to keep your 1990 Harley-Davidson Electra Glide Police FLHTP running reliably.
Oil Service
Requires 20W-50 motorcycle oil. The 'three-hole' service includes the engine (approx. 4 qts), primary (approx. 1 qt), and transmission (approx. 24 oz).
Air Seat Pressure
The solo seat bladder requires regular pressure checks. Normal operating range is 20-60 PSI; exceeding 100 PSI can rupture the bladder.
Common Wear Items
Parts that wear over time on the 1990 Harley-Davidson Electra Glide Police FLHTP and should be inspected regularly.
Cylinder Base Gaskets
Original paper gaskets are notorious for 'weeping' or leaking oil at the base of the cylinders due to thermal expansion cycles.
Swingarm Bushings (Cleveblocks)
The rubber-and-silicone bushings wear out, leading to the 'bagger wobble'—an unstable oscillation at highway speeds.
Popular Upgrades
The most popular aftermarket upgrades for the 1990 Harley-Davidson Electra Glide Police FLHTP.
Stabilizer Kits
Aftermarket links (like Sta-Bo or True-Track) are installed to stiffen the rubber-mounted drivetrain and eliminate lateral swingarm movement.
CV Carburetor Tuning
Re-jetting the Keihin CV carburetor and adding a high-flow air cleaner is the standard 'Stage 1' to wake up the restricted Evo engine.
Common Replacement Parts
Parts that commonly need replacing on the 1990 Harley-Davidson Electra Glide Police FLHTP.
Inner Cam Bearing
The factory INA bearing used a plastic cage that can fail. Owners frequently replace this with a full-complement Torrington (B-138) bearing for engine safety.
Stator and Voltage Regulator
High-heat environments and age lead to stator failure or burnt regulator plugs, causing charging system loss.
Used Buying Inspection Checklist
What to look for when buying a used 1990 Harley-Davidson Electra Glide Police FLHTP.
Base Gasket Seepage
Check the area where the cylinders meet the engine cases for oil residue; a heavy leak requires a top-end teardown.
Air Seat Integrity
Pump up the seat and listen for hissing or check if it holds pressure overnight; bladders are expensive to replace.
Drive Belt Condition
Inspect for cracks or missing teeth. Replacing the belt on this era FLH requires removing the entire primary drive.
Your cart is empty