Collection: Genuine Keihin 393 Series Main & Main Air Jets

Genuine Keihin jets, direct from the source. As an authorized Keihin distributor, we guarantee these jets are the real deal  — never aftermarket reproductions or "Keihin-style" copies. You get the exact part, machined to Keihin's specifications in Japan.

Same-day shipping. Orders placed by noon ship the same day, so you're not waiting to get back on the road or the trail.

Main jet or main air jet? The 393 series serves double duty. Depending on your carburetor and setup, these jets meter fuel as a main jet or meter air as a main air jet. Many Honda models use these as main jets. The physical part is the same — your application determines its role. A larger main fuel jet will richen your mixture.  A larger main air jet will lean your mixture. If you're unsure which you need, check your carburetor's specifications or contact us before ordering.

Finding your size. Jet sizing depends on your specific engine, modifications, and conditions. If you already know your size, find it in the list above. If you're matching to an existing jet, measure or reference your current part number. When in doubt, reach out and we'll help you confirm.

A note on cross-references. Some Honda part numbers shown are inferred from historical catalog data and OEM supersession patterns, and are provided to help you cross-reference. We recommend confirming fitment against your application before ordering. If you need help verifying a number, contact us.