393957 393957S Air Filter for Briggs Stratton 390930 393957 393957S 4106 7-18 HP Horizontal Engines with 271794S 270782 Pre Filter for John Deree PT9334 PT4301 LG393957 LG393957S Lawn Mower

What It Is

This is a dual-element air filter set (main filter + pre-filter) designed for Briggs & Stratton horizontal shaft engines in the 7-18 HP range. Commonly used on riding mowers, lawn tractors, and zero-turn mowers, it replaces OEM part numbers 393957, 393957S, 390930, and 4106.

Fitment & Compatibility

Before buying, confirm your engine has a horizontal shaft (not vertical). This filter fits Briggs & Stratton engines like the 28N707, 31C707, 40N877, and similar 7-18 HP models. It also works on John Deere models PT9334 and PT4301. Check your engine’s model number (stamped on the blower housing) and cross-reference with 393957 or 393957S. The main filter measures about 4.25” x 3” x 1.5” and the pre-filter is a foam sleeve. Not for vertical shaft engines or small push mowers.

Key Things to Know

• Dual-element design: The foam pre-filter catches larger debris, extending the paper filter’s life. Clean the foam every 25 hours, replace the paper yearly.
• Installation is easy: Remove the old filter, slide the pre-filter over the paper element, and press into the housing. No tools needed.
• Common gotcha: Some aftermarket versions may be slightly undersized, causing air leaks. This set is reported to fit snugly with no gaps.
• Quality note: The foam pre-filter is washable—rinse with soapy water, dry completely before reusing. The paper filter is dry-type, not oiled.

Should You Buy It

If you own a Briggs & Stratton horizontal engine lawn tractor or John Deere PT9334/PT4301 and need a cost-effective replacement for the OEM filter, this $7.99 set is a solid choice. It’s a direct fit, easy to install, and the dual-element design adds extra protection. Skip it if your engine uses a different filter shape or you need a vertical shaft model.