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!
Valve Guide Overview
Imported Chinese Scooters are typically based on clones of the honda GY6 QMB139 engine and transmission. These engines can suffer from
premature valve guide wear, particularily if regular oil changes are nit maintained. Valve guides are usually bronze or steel and are tubular in shape. The valve guides keep the valves straight and in position in
the cylinder head and if they wear oil can seep through into the cylinders causing blue smoke, a common sight on cheap import scooters and motorcycles.
Valve Guide Replacement Procedure, Chinese Import Scooter Clone
Applies to: Baotian, Sukida, Hoatian, Lifan, JMStar, Jinlun, Kymco, Tank, Quinqzi, PGO, Roketa, Strada and Taishan QingQi and many more...
Valve Guide Removal
Changing the valve guides on your chinese import scooter is a fairly advanced procedure but is achievable by a reasonably experienced amature. To do this properly you really need a press to press the valve guides out of the cylinder head.
Before starting, follow the instructions in this manual for Valve Removal as this will lead you to a suitable point to start this procedure.
- Remove the camshaft, Cylinder Head and Valves from your clone Chinese scooter. (Start here, Camshaft Removal for detailed instructions and then return to this page.)
- Once you have the valves and springs out of the Cylinder Head, ream any carbon or deposits out of the valve guides and measure for wear. Refer to your manufacturers specification, but an internal diameter of more than 5.3mm typically shows too much wear.
- To remove the guides, first heat the cylinder head to around 100 degrees centigrade, then remove the guides using a press, taking care not to burn yourself. NOTE: You may be able to pry the valve guide out but avoid damaging the cylinder head.
- Making sure the cylinder head is still hot, press the new Valve Guides into position taking care to oil the rubber O-Ring.
- Now, check the internal diameter of the valve guide and use a reamer to adjust if necessary.
- Carefully clean the cylinder head and remove any debis or swarf.
Notes
Tools such as a reamer and press are specialist tools. If you are unsure or wary about undertaking such a big job on your chinese clone 50cc scooter then it may be best to trust this job to a mechanic.
If you do decide to go ahead and fix your import scooter motorcycle yourself, then remember to use cutting oil when using the reamer and to keep the reamer spining even when pulling it out or pushing it in.