Prima Keihin PB Main Jet Kit (4mm, 10 pcs); 139QMB, Gen 50cc
Prima 4mm Main Jet Tuning Kit – Keihin PB & CVK Carburetors
$25.46
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Product Details
Description
Prima 4mm Main Jet Tuning Kit – Keihin PB & CVK Carburetors
Key Details
- Original Parts For Scooters SKU: 114-49-10PCS
Specifications
- Overall Length: 7mmnnJet Body Diameter: 5mmnJet Thread Size: M4 x 0.7mm fits 4mm main jet ports.n70 Main Jet Inner diameter: 0.70mm (70) nn75 Main Jet Inner diameter: 0.75mm (75) nn80 Main Jet Inner diameter: 0.80mm (80) nn85 Main Jet Inner diameter: 0.85mm (85) nn90 Main Jet Inner diameter: 0.90mm (90) nn95 Main Jet Inner diameter: 0.95mm (95) nn100 Main Jet Inner diameter: 1.00mm (100) nn105 Main Jet Inner diameter: 1.05mm (105) nn110 Main Jet Inner diameter: 1.10mm (110) nn115 Main Jet Inner diameter: 1.15mm (115)nnPackaging may vary from product photosnCompatibility:nnGenuine Buddy 50nGenuine Roughhouse 50nnnGenuine Rattler 50nGenuine Black Cat 50nnnChicago Scooter Co. go. 50nChicago Scooter Co. go. Max 50nnnChicago Scooter Co. Nitro 50nChicago Scooter Co. Bella 50nnnKeihin 50cc carburetorsn50cc CVK Style CarburetorsnnnPD18J CarburetorsnAnd many other PB and CVK-style carburetorsnnJetting takes trial and error to obtain optimal performance from your scooter. Many scooters are jetted lean from the factory to meet emissions requirements. Learn more on our Carburetor Jetting 101 page. Additionally, there are many good tutorials on how to properly jet a carburetor and you should refer to them to ensure you do not damage your engine by jetting too lean.About Prima: Prima is the industry leader in premium scooter accessories, service parts and scooterist protective apparel. Prima brand products are designed direct-fit for all popular scooter brands including Honda, Yamaha, Genuine, Vespa, SYM, Lance, KYMCO, Royal Alloy and GY6 / QMB powered scooters.nnSPECIFICATIONS: Specifications:nRound, Keihin PB style jetsnKit contains 10 different jet sizes: 70 – 115nOverall Length: 7mmnnJet Body Diameter: 5mmnJet Thread Size: M4 x 0.7mm fits 4mm main jet ports.n70 Main Jet Inner diameter: 0.70mm (70) nn75 Main Jet Inner diameter: 0.75mm (75) nn80 Main Jet Inner diameter: 0.80mm (80) nn85 Main Jet Inner diameter: 0.85mm (85) nn90 Main Jet Inner diameter: 0.90mm (90) nn95 Main Jet Inner diameter: 0.95mm (95) nn100 Main Jet Inner diameter: 1.00mm (100) nn105 Main Jet Inner diameter: 1.05mm (105) nn110 Main Jet Inner diameter: 1.10mm (110) nn115 Main Jet Inner diameter: 1.15mm (115)nnPackaging may vary from product photosnnnCOMPATIBILITY: Compatibility:nnGenuine Budd
Compatibility / Fitment
Use the fitment details below to confirm this part matches your scooter before ordering.
- Engine Size: 50cc, GY6
- Fits Models / Common Applications: Genuine Buddy and other compatible models may apply.
- Fitment Notes: Performance, Auto Transmission
Fitment Guide: This compatibility information is based on manufacturer and supplier data. Listed models are common known applications and may not include every compatible scooter. If your scooter has multiple versions or production changes, confirm the correct match before ordering. Check photos, measurements, original part numbers, engine code, model, and related fitment information whenever possible.
Common Fitment Questions
Q: Will this fit a Genuine?
A: This SKU is listed with Genuine model fitment where the scooter also matches the listed engine or fitment notes.
Q: Is this for 50cc scooters?
A: This SKU is listed with 50cc engine-size fitment. Confirm exact model, year, and part style before ordering.
Additional information
| Weight | 0.3 lbs |
|---|---|
| Dimensions | 3 × 3 × 1 in |
| Condition | New |
|---|
Fine-Tune Your Fuel: 10-Piece Prima 4mm Main Jet Kit
Standard factory jetting is almost always "lean" to meet emissions standards, which can leave your scooter feeling sluggish. The Prima 4mm Main Jet Kit is the essential tool for riders installing big-bore kits, performance exhausts, or high-flow air filters. With 10 precision-machined sizes, you can eliminate "flat spots" and find the perfect air-fuel ratio for maximum throttle response.
The Tuner’s Advantage
- Complete Range: Includes 10 sizes (#70, #75, #80, #85, #90, #95, #100, #105, #110, #115) to cover everything from stock to fully-modified builds.
- Precision Machined: Every jet is stamped with its size and built to strict tolerances, ensuring consistent fuel flow across the entire RPM range.
- Universal 4mm Thread: Specifically designed for Keihin PB, CVK, and PD18J carburetors commonly found on 50cc–125cc scooters.
- Value Bundle: Buying a kit is 60% more cost-effective than purchasing individual jets during the trial-and-error tuning process.
Comprehensive Fitment Guide
This 4mm kit fits most 50cc to 125cc "retro" and performance scooters using a 139QMB engine or Genuine 2-stroke platforms:
| Brand | Compatible Models |
|---|---|
| Genuine Scooter Co. | Buddy 50, Roughhouse 50, Black Jack 50, Buddy 125 |
| Kymco | Agility 50, Super 8 50, People 50 (4-Stroke) |
| SYM | Orbit 50, Fiddle II 50, Jet 50 |
| CSC / Wolf / Amigo | Bella Classic, Lucky, Avenza, and most 139QMB builds |
| Honda | Metropolitan (CHF50), Ruckus (NPS50) - *Check thread first* |
Technical Specifications
- Thread Size: M4 x 0.7mm
- Jet Body Diameter: 5mm
- Overall Length: 7mm
- Material: High-Grade Brass
- SKU: 114-49-10PCS
Pro Tuning Tip: Always start with the largest jet first and work your way down. A "rich" mixture (too much fuel) is safe, but a "lean" mixture (too little fuel) can cause your engine to overheat and seize. Look for a "toasted marshmallow" brown color on your spark plug for the perfect tune.
Note: Not compatible with Mikuni or Dellorto carburetors. Please verify that your current jet has an M4 thread before ordering.
Original Parts For Scooters SKU 114-49-10PCS, 114-85-10PCS
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