Index
Overview
Tuning
Tuning Overview
Lighter Roller Weights
Remove Variator Restrictor
Stiffer Clutch Springs
Move Needle Jet Washer
Increase Fuel Jet Size
Carb De-restriction
Un-Restricted CDI Unit
Un-Restricted Air Inlet
Trouble Shooting
Compression Test
Fuel Enricher Test
Seized Brake Caliper
General Maintenance
Replace Air Filter
Check & Change Oil
Spark Plug Change
Idle Speed Adjust
Change Brake Pads
Adjust Valve Lash
Electrical
Testing the Battery & Charging System
Battery Change
Coil Change
HT Lead Change
Transmission
Remove Starter Motor
Refurb Bendix Gear
Engine
Camshaft Removal
Valve Removal
Replace Valve Guides
Engine Removal
Return to Transport Listings
Models Covered
Lexmoto, Pulse, Sukida, Baotion, Lifan, Direct Bikes, Huatian, JMStar, QT50, LF50QT, YH50QT,
BT49qt, 139 QMB, Honda, GY6, Motorbike, Taishan, Jonway, Peugeot V-Clic, QT-4, QT-7, QT-9, qt-11, QT-50
Kymco, Tank, Quinqzi, PGO, Roketa, Strada, Vento, Yamati, QMB139, SunL, SYM, QingQi, Volano Plus Many More Chinese Motorcycles, mopeds and
scooters!
Fuel Jet Size
The main fuel jet in a motorbike, moped or chinese imported scooter, controls how much fuel can escape into the inlet manifold to mix with the air. Larger main jets can increase performance of your scooter, but go too large and the engine will run rich, be inefficient and have stalling and running problems.
Steps to Change a Scooters Main Fuel Jet Size
Applies to: Baotian, Sukida, Hoatian, Lifan, JMStar, Jinlun, Kymco, Tank, Quinqzi, PGO, Roketa, Strada and Taishan QingQi and many more...
Changing Your Fuel Jet
Changing the fuel jet size is a common way for people to improve the performance of their chinese import GY6 scooters. By fitting too small a jet manufacturers can limit the performance of the scooter to comply with speed restriction laws. Do not assume that opting for a bigger fuel jet will automatically improve performance, the scooter may already have a suitable size main jet and be restricted in some other way.
For a stock 50cc GY6 engine, anything bigger than a 90 sized main jet will make the engine run too rich. Generally speaking, between sizes 85 and 90 is thought to be about right.
- Gain access to your scooters carburetor by removing the panel under the seat. You will need to disconnect the inlet manifold, air intake, fuel line, throttle cable and automatic choke connector.
- You can now remove the carburetor. Turn it upside down and remove the three cross head screws to gain access the float chamber.
- Your scooters Main Jet is shown in the picture below. Undo the jet using a flat blade screwdriver whilst gripping the outer brass jet holder with a pair of pliers.
Notes
There will inevitably be fuel spillage when changing your 4 stroke chinese scooters main jet. Have plenty of rags around to wipe up any spilt fuel.
The main fuel jet is very small and looks nothing like a jet, it is simply a small brass screw with a hole in it! The size of the hole determines its size.