Mikuni Large Round Main Jets - 4/PK #90

Genuine Mikuni large round main jets in #90 size, sold in a 4-pack for carburetor tuning on V-twin motorcycles. These jets meter fuel flow through the main circuit and are essential when rejetting a carb for different air filters, exhausts, or elevation changes.

Features

• 4-pack quantity
• Genuine Mikuni OEM jets
• Large round body style
• #90 size for main circuit tuning

Specifications

• Brand: Mikuni
• Manufacturer Part #: FN100604-90
• Jet Size: #90
• 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 using large round main jets.

Frequently Asked Questions

What does a #90 main jet do?

The main jet controls fuel flow in the main circuit — used at cruise and part-throttle RPMs. Upsize for richer mixture, downsize for leaner.

Why would I need to rejet?

Air filter changes, exhaust upgrades, altitude changes, or engine modifications often require rejetting for proper fuel-air ratio and smooth running.

How many jets are in a pack?

Four jets per pack — enough to try different sizes or stock a spare set.

Will these fit any Mikuni carb?

These are large round jets — verify your carb uses large round jets before ordering, as some Mikuni models use different jet body styles.