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!
CDI Unit
The CDI unit is a simple computer module that controls basic engine timing on a chinese import 50cc scooters and
other scooters and motorcycles fitted with a CDI ignition. Because the CDI computer controls the timing of the ignition spark
it can be used to restrict the maximum revs that your GY6 Scooter engine can reach.
Changing the CDI Unit for a De-Restricted Unit
Applies to: Baotian, Sukida, Hoatian, Lifan, JMStar, Jinlun, Kymco, Tank, Quinqzi, PGO, Roketa, Strada and Taishan QingQi and many more...
Fitting a performance CDI
There is often confusion between a de-restricted CDI and a performance CDI unit. In most cases, unless you make other major modifications to your chinese 50cc scooter, a performance CDI unit will be a waste of money as your engine will simply not rev high enough to benefit.
However, on some imported chinese 4 stroke scooters, the CDI unit is restricted to limit the engines maximum possible revs. Fitting a de-restricted CDI unit simply allows the scooters engine to rev normally.
- The CDI unit is normally located in the battery box, underneath your feet as you sit on your scooter. Remove the battery cover to gain access.
- In many cases, the CDI unit can simply be pulled out and disconnected from the wiring harness. A replacement de-restricted CDI unit can then be plugged in!
- Note: We would recommend trying to remove any other forms of restriction on your scooter before buying a replacement CDI.
- On some scooters there is a sensor fitted to the variator cover that detects the rpm of the engine. Once the revs reach a certain limit, the CDI unit cuts down the spark, reducing power. Rather than buying a new CDI, cut the wires from this sensor and see if it does the trick!
Notes
Its hard to know whether your chinese GY6 clone has a restricted CDI unit or not. If you have removed any other possible performance restrictors (see our Tuning Guide) and your scooter is still very slow (sub 30mph) then it may be worth exchanging the CDI unit.