GY6 Maintenance

You will often hear that chinese scooters are just “junk” but you will notice that there are a few that continue to be able to ride their scooters without problems. Understanding your scooter’s needs and flaws early on will avoid you from becoming strayed on the side of the curb.

Below you will find the basic maintenance and schedule one should perform on their scooter. Please understand that as scooters differ some from manufacturers to manufactures, the information below is purely for references only. The site is not liable for damage caused due to misinterpretation of information provided.



WARNING: Always make sure you are in a well ventilated area before the engine starts. Never start the engine in an enclosed area. Gasoline powered engine exhaust fumes are poisonous and can cause loss of consciousness and death. Do not smoke or allow open flames or sparks in or near the area where refueling is performed or where gasoline is stored.

3-2 Frame

  • Front brake lever free play: 10-20mm
  • Rear brake lever free play: 10-20mm


Tire type

    • Front: 3.00 x10
    • Rear: 3.00 x10


  • Front wheel axle nut 4.0-5.0kg/m
  • Rear wheel axle nut 8.0-10.0kg/m

3-3 Maintenance Chart

Perform regular maintenance, according to maintenance handbook.

1: Inspect, clean, lubricate, add fix or replace when necessary.

A: Adjust B: Clean C: Replace D: Tighten



  1. For mileage higher than what is specified in the chart, the maintenance should be repeated at the same interval listed.
  2. More frequent maintenance is required if the vehicle is used in dusty areas or in rain.
  3. More frequent replacement is required if the vehicle is subjected to severe use, such as heavy load operations, long trips or when operationing in rain.

3-4 Fuel Filter

  1. Remove luggage box (2-2)
  2. Check fuel line for ageing or damage.
  3. Replace with a new one in case damaged or leaking.

3-4 Throttle Lever Operation

  1. Check throttle for proper operation.
  2. Check throttle grip free play.
      • Free play: 2-6mm (.078 in.-236 in.)
      • Free play refers to the amount of “twist play” you have before the actual throttle cable is engaged to begin giving fuel to the engine.
  3. Adjust free play by using the adjusting nut in the throttle cable and the adjuster at the carburetor.
      • Major adjustments should be performed at carburetor.
      • Adjust it by loosening the jam nut by the carburetor and rotating adjuster nut.
      • Fine adjustments should be performed by the throttle grip.
      • Remove outer rubber dust and element cover, loosen jam nut and rotate adjuster nut to adjust throttle tension.

3-5 Air Filter

Filter Replacement 

  1. 38aRemove air filter cover by unscrewing necessary bolts.
  2. Check filter for dirt or damage.Replace if necessary or in accordance to maintenance schedule.

Do not attempt to wash the filter element unless using aftermarket reusable filters. Cleaning disposable filters risk filter elements to eventually fray or tear, enter into engine, and cause costly damage.

Below you will find a video of how to change air filter on a Kymco 200i. In theory most scooters are similar other than the process of removing body plastics to have access of the air filter.

3-5 Replacing Frequency

  1. More frequent replacement is required if vehicle is driven in dusty roads or in the rain.
  2. Make sure the air filter cover is securely in place to ensure filter is properly sealed against rear cover. Loosely or incorrectly placed filters may allow outer elements to enter into engine and cause internal damage or excessive unnecessary wear.

3-5 Spark Plug


  1. Remove spark plug.
  2. Check spark plug for burning, dirt or deposit.
  3. Clean it with a spark-plug cleaner or steel brush in case of dirt or carbon deposits.
  4. Check spark plug gap Gap: 0.6-.07mm (.022-.024 in.)
  5. Check plug for dirt, carbon build-up or cracking of insulator.

3-6 Valve Adjustment


  • Always check and adjust with engine temperature lower than 35·c {95″F)
  1. Remove cylinder head cover.
  2. Rotate cooling fan to camshaft. Locate mark at center top, aligning magneto fly wheel mark with that on crankcase.
    • Magneto “T” mark and box crankshaft mark.
    • Valve gap checking and adjustment valve gap:
      • IN: 0.05mm (.00197 in.)
      • EX: 0.05mm (.00197 in.)
  3. To adjust the valve gap, loosen arm nut and rotate adjusting nut.

Valve Adjustment Wrench

Be sure to check valve gap again, after locking jam nut.

3-6 Carburetor Idle Speed

Idle adjustments should be performed after engine is sufficiently warmed.

  1. Remove cover.
  2. After the engine warmed, connect it to an engine revolution counter. (RPM gauge)
  3. Adjust idle screw until specified revolution is obtained. 
      • Minimum idling speed: 1900r/m±190r/m
  4. Readjust the screw if the idle speed is not steady or fuel cannot be properly applied.

3-7 Ignition Timing

  • Because GY6 engines are all equipped with a CDI (Capacitor discharge ignition), there is no need for ignition adjusting.
  • Check ignition system if ignition timing is incorrect.


  1. Remove right fan cover or
  2. Remove rubber ignition timing inspection cover.
  3. Check ignition timing by using a timing light. Crankcase mark must be aligned with mark “F” on flywheel while engine is at idle speed. The timing should advance as the RPM is increased.

The timing mark should align with the crankcase mark at 3000 RPM.

3-7 Cylinder Pressure

  1. Measure cylinder pressure with the engine warmed up.
  2. Remove spark plug.
  3. Install cylinder pressure gauge.
  4. With throttle valve fully open, start starter motor to measure cylinder pressure. (213psi)
    • Compression pressure: 15kg/cm2-600rpm.
  5. If the pressure is excessively low, check for the following:
      • Valve leakage
      • Valve gap too tight
      • Cylinder head gasket damaged
      • Worn piston rings.
      • Worn piston or cylinder
  6. Check combustion chamber and piston top for excessive deposits if compression pressure is too high.

3-8 Final Check of gear engine oil reduction

In order to accurately check oil volume, place scooter on center stand or use a wood block to level the scooter so that the engine is leveled horizontally to the ground.

  1. Unbolt gear oil adjusting bolt after stopping engine.
  2. The oil level should be just under the regulation screw bolt hole. Add gear oil when oil level is too low.
      • Gear oil recommended weight: SAE 90W
  3. Build up gear oil regulator screw bolt.
  4. Confirm whether or not the packing washer is broken.

Changing Gear Oil


  1. Remove gear oil adjusting bolt and drain oil.
  2. Confirm whether or not bolt gaskets are damaged.
  3. Place drain bolt back on motor.
  4. Add recommended gear oil into the fill bolt hole level to top of fill hole.
  5. Place fill bolt back in place and clean surrounding areas of any oil residue.
  6. Check for leaks after work is completed.

 3-8 Drive Belt (Transmission Belt)


  1. Detach the left crankcase cover (9-2).
  2. Check whether there is wear and tear of transmission belt.
      • Continuous Variable Transmission(CVT) Belt.
  3. Replace CVT belt with new one when necessary or according to maintenance schedule.


3-9 Rear Brake Arm (Brake shoe drum brakes)


    • Replace rear brake shoes or if there is a metal to metal scraping sound when braking or when adjusting or tightening (1) nut does not aid in rear brake function.




 3-8 Adjust Rear Brake Lever


  • Check free gap of rear brake bar.
  • Free gap: 10-20mm (0.5 in.).


3-9 Brake System-Front Brake


  1. Check free gap of front brake bar.
      • Free gap: 10-20mm (0.5 in.)
  2. Rotate adjusting nut to regulate free gap of brake lever.


 3-10 Front Lamp Adjustment


  1. Rotate nut to adjust free gap when it exceeds proper adjustment.
  2. Turn main switch to “on” and start engine.
  3. Rotate adjusting screw of front lamp to aim the light.






3-10 Clutch Engagement

  1. Start engine and increase RPM slowly to check performance of clutch.
    • Clutch should engage at 2200 RPM.
    • Service and replace clutch as necessary should slippage occur.

3-10 Front Suspension

  1. Pull front brake bar tightly and compress front for up and down to check its performance.
  2. Check for leakage of front for and/or soft springs.

Rear Suspension

  1. Compress rear shocks up and down to check performance.
  2. Check for leakage of rear shock or soft springs.
  3. Suspend rear wheel and push it left and right to check engine suspension sleeve for wear.

3-11 Nut and Bolt Tightness

  1. Check all nuts and bolts for proper tightness.
  2. Adjust torque as necessary.

3-11 Collar Rim Tire

  • Check tire pressure.
  • Measure tire pressure when tire is cold. 
  • When tire is warm, the air inside expands and gives an incorrect reading. Tire manufacture’s recommended tire pressure (PSI) is set at an amount when tires are “cooled.” 

3-11 Air Pressure44

  • Front Tire 1.75kg/cm – 17psi
  • Rear Tire 2.00kg/cm – 23psi

3-11 Tire Standards

  • Front tire: 3.00 x 10
  • Rear tire:  3.00 x 10
  1. Check if front wheel axle has slack.
  2. Check if rear wheel axle nut has slack.
  3. Tighten when necessary to stipulated torque if there is slack.


Although 10″ rims are common, most Chinese & Taiwanese scooters with 125cc and 150cc’s run 12″ or larger rims. Refer to the information embedded on the walls of your tire to match to correct replacement tires. Running different size tires on wheels places riders highly at risk for falls and injuries.

Dennis Kirk online retailer has detailed information explaining tires. Choosing correct tires involve

      1. Correct rim size
      2. Correct height and width
      3. Correct tire compound (Type of rubber type) for the application of the vehicle.


  • Front wheel axle nut 4.0-5.0 kg-m 28-32 ft/lbs
  • Rear wheel axle nut 8.0-10.0 kg-m 55-65ft/lbs

3-12 Steering



  1. Swing handlebars left and right to check if there is interference from the wires.
  2. Grasp handlebars and rotate from left to right while holding the front wheel straight. There should be slippage.
  3. Check steering bearing adjustment. Fork should turn freely with play in bearing.


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