Main Jet for Keihin Style PB, PAB and CVK Carburetors- 4mm

Fine-tune your air-fuel ratio with these high-precision Keihin Small Round 4mm Main Jets. Designed for Keihin PB, PAB, and CVK series carburetors, these are the standard jet for optimizing performance after installing a big-bore kit, exhaust, or high-flow air filter. The M4x0.70 thread and 5mm round head match the Keihin 99101-116 style used across a wide range of 50cc–150cc scooters. Available in 15 sizes from #75 to #130 — select your size from the variant dropdown.

Compatibility note: These are Keihin "Small Round" (99101-116) style jets. Not compatible with Keihin "Large Round" (99101-393) or "Hex" (99101-357) styles. Verify your jet dimensions before ordering.

Jetting tip: Always start with a larger jet than you think you need and work down. Running too lean can cause engine overheating and permanent damage. See our Jetting Instructions for a full guide.

Key Features

• Keihin Small Round style (99101-116) — M4x0.70 thread, 5mm round head
• High-grade machined brass for precise fuel metering
• Available in 15 sizes: #75, #80, #85, #90, #95, #98, #100, #102, #105, #110, #115, #120, #125, #128, #130
• Fits OEM and aftermarket Keihin PB, PAB, NCV, and CVK carburetors (17–26mm)
• Not compatible with Large Round (99101-393) or Hex (99101-357) styles

Specifications

• Jet Style: Keihin Small Round (99101-116)
• Thread: M4 x 0.70mm (~3.9mm OD measured)
• Total Length: 7.0mm
• Head Diameter: 5.0mm
• Material: Machined brass
• Available Sizes: #75 through #130 (15 sizes)

Compatibility

California Prop 65 Warning: www.p65warnings.ca.gov

• Keihin Small Round style (99101-116) — M4x0.70 thread
• High-grade machined brass for precise metering
• Available in 15 sizes: #75 through #130
• Fits OEM and aftermarket Keihin PB, PAB, NCV, CVK carburetors
• Not compatible with Large Round (99101-393) or Hex (99101-357) styles

Jet Style: Keihin Small Round (99101-116) | Thread: M4 x 0.70mm | Dimensions: 7mm length x 5mm head | Material: Machined Brass | Sizes: #75, #80, #85, #90, #95, #98, #100, #102, #105, #110, #115, #120, #125, #128, #130

Genuine Buddy 50 (stock #74) | Genuine Buddy 125/150 (stock #90) | Genuine RoughHouse 50 | GY6/139QMB 50cc & 150cc CVK carbs | Keihin PB, PAB, NCV, CVK 17-26mm | Select Honda, Yamaha, SYM 4-stroke with Keihin CVK