793569 793685 Air Filter Tune Up Service Kit Replacement for Briggs Stratton Intake 20-21 HP

What It Is

This kit includes an air filter, pre-cleaner, spark plug, and fuel stabilizer for 20-21 HP Briggs & Stratton Intek V-Twin engines. It’s used for annual tune-ups on riding mowers, zero-turn mowers, and tractors with those engines.

Fitment & Compatibility

Check your engine model number – this kit fits Briggs & Stratton Intek V-Twin engines (20-21 HP, typically 540cc to 656cc). Look for a model number like 31P977 or 31R907 on the engine shroud (not the mower deck). The OEM air filter part numbers are 793569 (main filter) and 793685 (pre-cleaner). This is an aftermarket replacement, not OEM. Measure your existing filter – the main filter is roughly 6.5” long x 4” wide x 2” thick. Does not fit single-cylinder or older Briggs engines. Spark plug gap should be set to 0.030” before installation.

Key Things to Know

• Quality is decent – users report good filtration and fit, though the pre-cleaner foam may be slightly thinner than OEM. Works fine for residential use.
• Easy install – swap air filter and pre-cleaner (no tools), replace spark plug with a 5/8” socket, add fuel stabilizer to tank. Takes 15 minutes.
• Common gotcha – the spark plug included may not be pre-gapped. Check gap with a feeler gauge and adjust to 0.030” to avoid misfire.
• Fuel stabilizer – the included packet treats up to 5 gallons. Don’t pour it into an empty tank; add after filling to mix properly.

Should You Buy It

If you have a 20-21 HP Briggs Intek V-Twin and want a cheap, complete tune-up kit for one season, this is a solid value. Skip it if you prefer OEM parts or need a longer-lasting pre-cleaner for heavy-duty commercial use.