Precision Tuning: Keihin Style 4mm "Small Round" Main Jets Fine-tune your air-fuel ratio with these high-precision 4mm Main Jets . Designed for Keihin PB, PAB, and CVK series carburetors, these jets are the essential component for optimizing performance after installing a big-bore kit, exhaust, or high-flow air filter. These are "Small Round" (99101-116) style jets, featuring an M4x0.70 thread. Technical Specifications Jet Style: Keihin Small Round (99101-116 Style) Thread Pitch: M4 x 0.70mm Dimensions: 7mm (Total Length) x 5mm (Head Diameter) Material: High-Grade Machined Brass Available Sizes: #75 through #130 Comprehensive Fitment & Compatibility These 4mm jets are the standard for many OEM and aftermarket 50cc to 150cc carburetors: Carburetor Types Compatible Models Keihin Series PB, PAB, NCV, CVK (17mm, 20mm, 22mm, 24mm, 26mm) Genuine Scooters Buddy 50 (Stock #74), Buddy 125/150 (Stock #90), RoughHouse 50 GY6 / 139QMB Most Chinese 50cc & 150cc CVK Carburetors (TaoTao, Wolf, Ice Bear, Bintelli) Japanese Models Select Honda, Yamaha, and SYM 4-stroke models using Keihin CVK units. Tuning Advice: Always start with a larger jet than you think you need and "jet down." Running too small (lean) can cause engine overheating and permanent damage. For a comprehensive guide, visit our Jetting Instructions Blog . Note: Not compatible with Keihin "Large Round" (99101-393) or "Hex" (99101-357) styles. Please verify your jet dimensions before ordering. Original Parts For Scooters SKUs 114-36-75, 114-36-80, 114-36-85, 114-36-95, 114-36-100, 114-36-105, 114-36-110, 114-36-120, 114-36-125