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SYM · Two-stroke single, premix, CVT belt drive

Jet 50

Library entry covers 2002-2025

23 factory 35 guideline

Published source

SANYANG (SYM) Jet 50/100 and Jet Euro 50/100 Service Manual, Periodical Maintenance Schedule p.2-2 (factory PDF, copy on archive.org)

Factory workshop manual. Covers Jet 50/100 and Jet Euro 50/100 (two-stroke) service manual.

Open the source

58 items for a 2025 model, grouped by interval the way a factory chart is laid out.

How this bike is built (what the schedule is based on)

Engine cycle: Two-stroke
Engine lubrication: Two-stroke premix (oil in fuel)
Oil filtration: None (no filter)
Valve gear: None (two-stroke porting)
Ignition: Electronic (CDI / transistor / ECU)
Charging: Alternator / stator with rectifier
Battery: Wet cell (flooded lead-acid, needs topping up)
Fuel system: Fuel injection
Cooling: Air / oil cooled
Primary drive: Gear or chain inside engine, shares engine oil
Gearbox oil: Separate gearbox oil
Clutch control: Automatic or semi-automatic
Final drive: Belt CVT, scooter automatic
Front suspension: Telescopic fork
Rear suspension: Swingarm, single shock / cantilever
Front brake: Disc, hydraulic
Rear brake: Drum (or band / belt rim)
Wheels: Cast / alloy, tubeless
Sidecar: No sidecar

Maintenance schedule

2025 SYM Jet 50

On the road: every 150 mi

1 item

Check two-stroke oil tank / carry premix oil

Pre-ride / on the road

Guideline

Running a two-stroke out of oil seizes it. Injection bikes: check the tank. Premix: carry oil and a measure.

On the road: every 300 mi

1 item

Check lights, horn, brake light switches

Pre-ride / on the road

Guideline

On the road: every 621 mi or 1 month

1 item

Check tire pressures

Pre-ride / on the road

Factory

Manual: Tire pressure. Factory: I every 1000 km.

Every 621 mi or 1 month

6 items

Every screw tightening check

Engine

Factory

Factory: I every 1000 km.
Idle speed check

Engine

Factory

Factory: I every 1000 km.
Carburetor

Fuel and air

Factory

Factory: I every 1000 km.
Check / set ignition timing

Ignition and electrics

Factory

Manual: Ignition timing. Factory: I every 1000 km.
Clean battery terminals, check charge and strap

Ignition and electrics

Factory

Manual: Battery inspection. Factory: I every 1000 km.
Check brake pads and discs

Brakes

Factory

Manual: Brake & free play check. Factory: I every 1000 km.

Every 1,000 mi or 6 months

2 items

Adjust rear drum brake and rod / cable linkage

Brakes

Guideline
Inspect tire tread, sidewalls and date codes

Wheels and tires

Guideline

Every 1,864 mi or 3 months

7 items

Check / bleed / adjust oil injection pump cable

Engine

Factory

Manual: Oil pump linkage operation check. Factory: I at 300 km and every 3000 km.
Check engine mounting bolts and plates

Engine

Factory

Manual: Engine bolt tightening. Factory: I every 3000 km.
Decarbonize exhaust ports, pipes and baffles

Engine

Factory

Manual: Carbon cleaning for cylinder head, cylinder, piston head, and exhaust system. Factory: I every 3000 km.
Replace spark plugs (two-stroke)

Engine

Factory

Manual: Spark plug check or change. Factory: I at 300 km; R every 3000 km.
Check throttle cable(s) free play and return

Fuel and air

Factory

Manual: Throttle operation. Factory: I every 3000 km.
Clean / inspect air filter

Fuel and air

Factory

Manual: Air cleaner. Factory: I at 300 km; C every 3000 km. Cols 300; 1k/1mo; 3k/3mo; 6k/6mo; 12k/1yr. Two-stroke.
Replace fuel lines

Fuel and air

Factory

Manual: Fuel lines. Factory: I every 3000 km.

Every 3,000 mi or 12 months

5 items

Adjust automatic / semi-automatic clutch

Primary and gearbox

Guideline
Inspect fork seals, stanchions and fork boots

Front end

Guideline
Check footrests, pegs, rear brake and gear lever pivots

Rear suspension and frame

Guideline
Grease and check center / side stand and springs

Rear suspension and frame

Guideline
Check wheel bearings for play

Wheels and tires

Guideline

Every 3,107 mi

1 item

Change final drive (rear drive) oil

Final drive

Factory

Manual: Gear oil change. Factory: R at 300 km; replacement for every 5000 km.

Every 3,728 mi or 6 months

5 items

Clean oil strainers / mesh screens

Engine

Factory

Manual: Engine oil filter cleaning. Factory: C at 300 km and every 6000 km.
Replace fuel filter

Fuel and air

Factory

Manual: Fuel filter. Factory: C (clean, replace if necessary) every 6000 km.
Check steering head bearing adjustment

Front end

Factory

Manual: Steering handle check. Factory: I every 6000 km.
Frame lubrication

Rear suspension and frame

Factory

Factory: L every 6000 km.
Inspect rear shocks for leaks and damping

Rear suspension and frame

Factory

Manual: Cushion operation check. Factory: I every 6000 km.

Every 4,000 mi or 12 months

3 items

Inspect, clean and gap spark plugs

Engine

Guideline
Inspect CVT drive belt, rollers / sliders and clutch shoes

Final drive

Guideline

Typical scooter interval. Your owner's manual figure governs; check belt width against the service limit.
Lubricate brake cam spindles, check linings and drums

Brakes

Guideline

Every 6,000 mi or 12 months

4 items

Check charging voltage and regulator / cut-out

Ignition and electrics

Guideline
Check swingarm bushes for play

Rear suspension and frame

Guideline
Lubricate control cables and lever pivots

Controls and cables

Guideline
Lubricate speedometer / tachometer cables, check drive

Controls and cables

Guideline

A dry speedo cable whips the needle and eventually kills the instrument.

Every 7,456 mi or 12 months

3 items

Check cylinder head bolt torque

Engine

Factory

Manual: Engine screw torque. Factory: I every 12000 km.
Replace air filter element

Fuel and air

Factory

Manual: Air cleaner. Factory: R every 12000 km / 1 year.
Inspect drive belt, pulleys and tension

Final drive

Factory

Manual: Driving belt check. Factory: I every 12000 km.

Every 10,000 mi or 2 years

2 items

Compression test (or leak-down)

Engine

Guideline
Change gearbox oil

Primary and gearbox

Guideline

Every 12,000 mi or 2 years

3 items

Synchronize throttle bodies

Fuel and air

Guideline
Clean and grease rear suspension linkage

Rear suspension and frame

Guideline
Grease swingarm pivot

Rear suspension and frame

Guideline

Every 12,000 mi or 3 years

1 item

Replace CVT drive belt

Final drive

Guideline

Typical scooter interval, or sooner if the belt is cracked, glazed or below its width limit.

Every 15,000 mi or 3 years

1 item

Change fork oil

Front end

Guideline

Some early telescopic forks are grease filled or use very small oil quantities. Check your manual.

Every 15,000 mi

1 item

Replace brake linings / skim drums (wear based)

Brakes

Guideline

Every 16,000 mi or 4 years

1 item

Replace spark plugs

Engine

Guideline

Every 20,000 mi or 4 years

2 items

Repack / replace steering head bearings

Front end

Guideline

Many old machines use loose balls in cups and cones. Taper roller conversions are common.
Repack / replace wheel bearings

Wheels and tires

Guideline

Cup-and-cone and taper roller hubs need periodic repacking and adjustment.

Every 25,000 mi or 6 years

1 item

Replace swingarm bushes / bearings

Rear suspension and frame

Guideline

Every 30,000 mi or 6 years

1 item

Rebuild forks: seals, bushes, springs

Front end

Guideline

Every 2 years

3 items

Inspect wiring, bullet connectors and ground points

Ignition and electrics

Guideline
Inspect frame, welds and lugs for cracks

Rear suspension and frame

Guideline
Replace brake fluid

Brakes

Guideline

Every 4 years

2 items

Inspect brake hoses; replace old rubber

Brakes

Guideline
Rebuild calipers and master cylinders (seals)

Brakes

Guideline

Every 6 years

1 item

Replace tires on age (regardless of tread)

Wheels and tires

Guideline

Guideline lines: Intervals here are general guidelines for the machine's era and layout, compiled for this app. They are not factory manual figures. Check your workshop manual, and edit any interval in the bike's Schedule tab.