Mikuni Large Round Main Jets - 4/PK #137.5

Mikuni large round main jets in size #137.5, sold as a 4-pack for carburetor tuning on V-twin motorcycles. These genuine Mikuni jets dial in fuel delivery to match engine modifications and riding conditions.

Features

• 4-pack quantity
• Genuine Mikuni large round design
• Size #137.5 main jet

Specifications

• Brand: Mikuni
• Manufacturer Part #: FN100604-137.5
• Quantity: 4 per pack
• Length: 4.4 in
• Width: 2.2 in
• Height: 0.6 in
• Weight: 0.05 lbs
• Country of Origin: Japan

Fitment

Fits V-twin motorcycles equipped with Mikuni carburetors requiring a #137.5 main jet.

Frequently Asked Questions

What size jet do I need for my bike?

Jet sizing depends on your engine displacement, carburetor model, altitude, and modifications. Consult your carb manual or a tuning specialist to confirm #137.5 is correct.

Why buy a 4-pack?

Four jets let you experiment with jetting changes, keep spares, or outfit multiple carburetors on a twin-carb setup.

Are these OEM Mikuni parts?

Yes — genuine Mikuni manufacturer parts, not aftermarket copies.

How do I install main jets?

Main jets screw into the carburetor bowl. The carb must be removed and partially disassembled. If unfamiliar with carburetor work, have a shop handle installation.