Introduction
Thank you for purchasing the NIBBI Carburetor and Air Filter kit. This manual provides essential information for the correct installation, operation, maintenance, and troubleshooting of your new carburetor. Please read these instructions carefully before using the product to ensure optimal performance and longevity.
Safety Information
NOTE
- This is a high-precision processed product. If you need to work on it, please do so in a clean environment.
- If, in the course of adjusting or disassembling, the carburetor is damaged, we as manufacturers do not accept responsibility.
- The carburetor function will be affected by factors such as air pressure, temperature, humidity, and height above sea level.
- This carburetor requires knowledge and understanding for its setup. If you lack either of these, contact a professional for advice.
EXPLANATION OF SYMBOLS:
- Note: Read information under this head carefully; it will help you understand the essential features.
- WARNING: Follow procedure accurately to avoid damage of the carburetor.
- NO FIRE: Make sure to stay clear of open flames and ignition sources to avoid unwanted fires.
- INSTALLATION CAUTION: Make sure all screws are tightened properly before starting the engine.
- READ CAREFULLY: If any information dealt with in the manual remains unclear, consult professional guidance.
Product Overview and Components
The NIBBI PE Carburetor kit includes the following main components:
- Carburetor
- Assembly Instructions
- Manifold
- Accelerator
- Throttle Cable
- Air Filter
- Main Jet (various sizes)
- Pilot Jet (various sizes)
- Fuel Filter
- Gasket
- Mounting Bolts and Nuts
Specifications
General Product Properties
| Attribute | Value |
|---|---|
| Brand Name | NIBBI |
| Item Weight | 0.6kg |
| External Testing Certification | CE |
| Origin | Mainland China |
| Air Filter | 45mm 49mm Foam Air Filter |
PE Flange Caliber Size and Jet Specifications
| PE Flange Caliber Size | Pilot Jet Options | Main Jet Options |
|---|---|---|
| PE17mm/19mm/22mm/24mm/26mm/28mm | #30, #32, #40, #35, #36, #45, #38, #42, #48 | #95, #112, #125, #140, #100, #113, #128, #145, #102, #115, #130, #148, #105, #118, #132, #150, #108, #120, #135, #110, #122, #138 |
Original Setting (Example)
| Carburetor | Stroke | Air Screw | Jet Needle | Main Jet | Pilot Jet |
|---|---|---|---|---|---|
| 24 | 15 | 3 | 3 | #105 | #40 |
| 26 | 15 | 3 | 3 | #110 | #40 |
| 28 | 15 | 3 | 3 | #115 | #40 |
| 30 | 15 | 3 | 3 | #128 | #40 |
Setup and Installation
Ensure all components are present and undamaged before beginning installation. Refer to the provided assembly instructions and diagrams for your specific vehicle model.
Installation Caution
- Make sure all screws are tightened properly before starting the engine.
- Always work in a clean environment to prevent contamination of the high-precision carburetor components.
Installation Video Guide
For a visual guide on the product, please watch the official product video:
Operation and Tuning
Basic Tuning Common Sense
- Air Screw: Turning the air mix screw will lean the mixture.
- Main Jet: The bigger the main jet, the richer the fuel mixture.
- Pilot Jet: The bigger the slow jet, the richer the fuel mixture.
- Jet Needle: There are five options per needle. The higher the number, the richer the mixture.
- Throttle Valve Opening: The throttle valve is inversely proportional to the fuel concentration. If the throttle valve is small, the fuel is rich; otherwise, the fuel is lean.
Tuning by Throttle Valve Opening
- For throttle closed to one-quarter throttle opening: According to the air input, change the slow jet to adjust the mixture. Running in a low speed, set the air adjustment screw to adjust the mixture.
- From one-quarter throttle opening to three-quarter throttle opening: According to the air input, change the jet needle position to adjust the mixture.
- From three-quarter throttle opening to full throttle: According to the air input, change the main jet to adjust the mixture.
- Half throttle to full throttle (high air speed in the carb): Adjust mixture by changing the main jet, jet needle, or jet needle setting.
Make sure to read the spark plug to check whether the setting is correct or not.
Basic Tuning Notes
- Basic jetting of the air screw is fully in, then 1 and a half turns out. If the engine runs too rich or too lean, try to adjust with the air screw. If this cannot be done within a few turns of the screw, change the slow jet.
- If the mixture is too rich between closed and half throttle, and this cannot be rectified with the air adjustment screw, go for a smaller slow jet.
- Running your engine too rich will result in your engine not running at its best. Running it too lean will eventually damage your engine's components such as the piston, cylinder, and head. We therefore recommend starting on the rich side when you set up your engine and work your way down to the proper setting.
- Check and read the spark plug to learn about the mixture your engine requires:
- Spark plug in black, or even wet: Your engine runs too rich. Unburnt fuel creates soot that builds up on the spark plug.
- Spark plug is dry and grey, or even white: Your engine runs too lean. This may lead to damage of engine components such as the piston, cylinder, head, and spark plug caused by overheating. Go for a richer setting, use larger jets.
- The spark plug is brown and looks clean: Mixture is as it should be.
- When changing to a larger main jet, this will affect your engine's performance at half to full throttle. Always change one factor at a time and assess the changes this has made to the engine's performance before changing something else.
- If you run an engine too lean for a longer period, it is likely to overheat and suffer damage.
Maintenance
Air Filter Cleaning
The foam air filter is designed to be durable and easy to clean. Regular cleaning ensures optimal engine performance and longevity.
- The sponge can be removed and cleaned with clean water.
- Allow the air filter to dry completely before reinstallation.
General Carburetor Care
- Keep the carburetor clean and free from dirt and debris.
- Periodically check all connections and fasteners to ensure they are secure.
Troubleshooting
Use the following table to diagnose and resolve common carburetor issues. If the problem persists, consult a professional.
| Problem | Mixture State | Setting Adjustment | Notes |
|---|---|---|---|
| When idling, engine runs erratic, RPM not stable | Lean | Turn air screw in clockwise to make mixture richer. Change to a bigger slow jet. | Possible broken reed petal or air-leak in inlet tract. |
| When idling, engine is stalled, exhaust fumes are black | Rich | Turn air screw out to make mixture leaner. Change to a smaller slow jet. Change to a larger diameter needle to make mixture leaner. | |
| When riding away, poor acceleration | Lean | Change to a bigger main jet. | |
| When riding away, engine runs erratic (between closed throttle and one-quarter throttle opening) | Rich | Change to a smaller main jet or thinner needle to make the mixture leaner. Turn the air screw in clockwise to make mixture richer. | |
| Rapid throttle opening, engine stalls | Lean/Rich | Check main jet and needle settings. | Could be caused by a broken reed petal or an air leak in the inlet tract. |
| Acceleration is hesitant or irregular (between closed throttle and one-quarter throttle opening) | Rich | Change the needle jet to a bigger one to make the mixture richer. | This may happen if the engine temperature is too high. Please check basic knowledge & adjustment. |
| Engine bogs (throttle between a quarter and half open) | Lean | Change the needle jet to a smaller one to make the mixture leaner. | Please check basic knowledge & adjustment. |
| Engine pings, detonation (throttle is fully open) | Lean | Change main jet to a larger one. | A piston could be out, or too much advance. Spark plug should be brown. An air leak in the inlet tract or a blocked air filter could also be causes. Check choke is not stuck. |
| Engine feels flat (throttle is fully open) | Rich | Adjust mixture by using a checking spark plug. |
User Tips
- Compatibility Check: Always verify the carburetor's compatibility with your specific engine model (e.g., YCF88S) before purchase and installation to ensure proper fit and function.
- Start Rich, Tune Down: When initially setting up, it's safer to start with a slightly richer mixture and gradually lean it out to find the optimal setting. This helps prevent engine damage from running too lean.
- Observe Spark Plug: Regularly check your spark plug's appearance as a primary indicator of your fuel-air mixture. A light brown color indicates a good mixture.
Warranty and Support
For detailed warranty information and further technical support, please refer to the official NIBBI documentation.
A comprehensive user manual in PDF format is available for download: NIBBI Carburetor User Manual (PDF).