Sym DD 50 Service Manual (English)

Questions and Answers:

L
Laura WilliamsJul 27, 2025
How to troubleshoot a Sym Scooter that is hard to start?
- T
  Tyrone PetersonJul 27, 2025
  If your Sym Scooter's engine is hard to start or won't start, begin by checking for fuel in the fuel tank. You can do this by loosening the carburetor drain bolt to see if there's gasoline inside the carburetor. Also, the spark plug might be the problem, so remove it, install it into the spark plug cap, and perform a spark test against the engine ground. Low compression pressure could also be the culprit, so perform a cylinder compression pressure test. Also check the spark plug to see if it is wet or dry.
J
Jennifer KlineAug 4, 2025
Why does my Sym Scooter engine run sluggish, especially at low speed and idling?
- J
  josephvelezAug 4, 2025
  If your Sym Scooter engine runs sluggishly, especially at low speeds and while idling, the ignition timing may be incorrect due to a malfunction of the CDI or AC generator; in this case, check the ignition timing using an ignition lamp. Also, the mixture may be too rich or too lean, so adjust the air screw of the carburetor. Air may be getting sucked through the carburetor gasket, so check the fuel supplying system in the automatic fuel cup. Finally, a poor spark could be the issue, so remove the spark plug, install it into the spark plug cap, and perform a spark test against the engine ground.
G
Gwendolyn AllenAug 11, 2025
What to do if Sym DD 50 Scooter engine runs sluggish and lacks power?
- D
  Darlene HillAug 11, 2025
  If your Sym Scooter engine runs sluggish and the speed does not pick up, or if it lacks power, the air cleaner might be clogged. Try gradual acceleration and check the engine speed. Also, the ignition timing may be incorrect, so check it using an ignition lamp. There may be no compression pressure, so check the cylinder compression pressure using a compression pressure gauge. The carburetor may be clogged, so check it. The spark plug may be fouled or discolored, so remove it. Finally, the engine may be overheating, so check it.
D
Danielle BoyleAug 18, 2025
Why does my Sym DD 50 Scooter engine run sluggish at high speed?
- S
  Shannon WilliamsAug 18, 2025
  If your Sym Scooter engine runs sluggish at high speed, the CDI may be malfunctioning, so check the ignition timing. Also, the fuel supply system in the automatic fuel cup may be poor, so check it. Finally, the carburetor may be clogged, so check if it is clogged.

Sym DD 50 Specifications

General

Fuel System	Carburetor
Ignition	CDI
Front Suspension	Telescopic Fork
Rear Brake	Drum
Engine Type	2-Stroke
Transmission	Automatic
Starting System	Kick start
Brakes	Drum

Summary

FORWARD

Manual Overview

Introduction to the service manual and its purpose.

HOW TO USE THIS MANUAL

Manual Navigation Guide

Instructions on how to navigate and use the manual's features.

MODEL ILLUSTRATION

Scooter Component Identification

Visual identification of scooter parts and their locations.

1. GENERAL INFORMATION

Symbols and Marks Explanation

Explanation of symbols and marks used in the manual.

General Safety Precautions

Essential safety guidelines for operating and servicing the scooter.

Specifications Overview

Key technical specifications for the DD 50 scooter.

Torque Values Reference

Standard torque values for various bolts and nuts.

Troubleshooting Common Issues

Diagnostic guide for common engine starting and performance problems.

Lubrication Points Diagram

Illustration showing all lubrication points on the scooter.

2. SERVICE MAINTENANCE INFORMATION

General Information and Specifications

Basic specs and maintenance overview for the DD 50.

Periodical Maintenance Schedule

Recommended maintenance intervals and tasks for the scooter.

Fuel & Oil System Maintenance

Procedures for servicing fuel lines, filter, engine oil, and oil pump.

Brake System Maintenance

Steps for checking and adjusting brake free play and wear.

Engine Adjustments & Timing

Procedures for checking and adjusting ignition timing and throttle.

Headlight Adjustment Procedure

Steps for adjusting the scooter's headlight beam.

3. LUBRICATION SYSTEM

Lubrication System Diagram

Diagram illustrating the lubrication system components.

Lubrication Precautions and Lubricant

Important precautions and recommended lubricant for the system.

Oil Pump Maintenance Procedures

Steps for removing, installing, and bleeding the oil pump.

Oil Tank Service

Procedures for removing and installing the oil tank.

4. ENGINE REMOVAL

Engine Removal Procedures

Step-by-step guide for removing the engine from the scooter.

Engine Installation Procedures

Step-by-step guide for installing the engine back into the scooter.

5. CYLINDER HEAD/CYLINDER/PISTON

Cylinder Head Maintenance

Procedures for removing, inspecting, and installing the cylinder head.

Cylinder and Piston Maintenance

Procedures for removing, inspecting, and installing the cylinder and piston.

Cylinder/Piston Troubleshooting

Common problems and solutions related to cylinder and piston.

6. ALTERNATOR

Alternator Maintenance and Inspection

Information on alternator maintenance and coil resistance values.

Alternator Removal Procedures

Step-by-step guide for removing the alternator assembly.

Alternator Installation Procedures

Step-by-step guide for installing the alternator assembly.

7. “V” TYPE BELT DRIVE SYSTEM/KICK-STARTER

Drive Belt Maintenance

Procedures for removing, inspecting, and installing the drive belt.

Kick Starter System Maintenance

Procedures for disassembling and assembling the kick starter.

Clutch and Pulley System Maintenance

Procedures for servicing the clutch and driven pulley components.

8. FINAL DRIVING MECHANISM

Final Drive Mechanism Maintenance

Information on gear oil, special tools, and troubleshooting.

Final Drive Mechanism Disassembly

Step-by-step guide for disassembling the final drive mechanism.

Final Drive Mechanism Reassembly

Steps for reassembling the final drive mechanism components.

9. CRANKCASE/CRANKSHAFT

Crankcase & Crankshaft Maintenance

Overview of crankcase disassembly and crankshaft inspection.

Crankcase Disassembly & Crankshaft Removal

Procedures for removing crankcase and crankshaft.

Crankshaft Inspection Procedures

Methods for measuring crankshaft clearances and run-out.

Crankcase Installation Procedures

Steps for installing the crankshaft and crankcase.

10. FUEL SYSTEM

Fuel System Maintenance & Troubleshooting

Overview of fuel system maintenance and troubleshooting.

Throttle Valve & Carburetor Service

Procedures for servicing the throttle valve and carburetor.

Float, Jet & Reed Valve Service

Procedures for servicing float, jets, and reed valve.

Fuel Pump & Air Cleaner Service

Procedures for servicing the fuel pump and air cleaner.

11. BRAKE SYSTEM

Brake System Maintenance & Troubleshooting

Overview of brake system maintenance and troubleshooting.

Front Disc Brake System Service

Procedures for servicing the front disc brake system.

Front/Rear Drum Brake System Service

Procedures for servicing front and rear drum brake systems.

Hydraulic Disc Brake Bleeding & Caliper Service

Steps for bleeding hydraulic disc brakes and servicing the caliper.

12. BODY COVER

Body Cover Overview

Illustration of all body cover components for different models.

Body Cover Maintenance & Disassembly Sequence

General precautions and sequence for disassembling body covers.

Front Cover & Spoiler Service

Procedures for removing and installing front cover and spoiler.

Side Covers & Fender Service

Procedures for removing and installing side covers and front fender.

Other Body Panels Service

Procedures for servicing luggage box, floor panel, and inner box.

13. STEERING/FRONT WHEEL/SUSPENSION

Steering & Wheel Maintenance

Maintenance info, troubleshooting, and torque values for steering/wheel.

Steering Handle Service

Procedures for removing and installing the steering handle.

Front Wheel Service

Procedures for removing, inspecting, and installing the front wheel.

Front Shock Absorber & Fork Service

Procedures for servicing the front shock absorber and fork.

14. REAR WHEEL/SUSPENSION

Rear Wheel & Suspension Maintenance

Maintenance info, troubleshooting, and torque values for rear wheel/suspension.

Rear Wheel Service

Procedures for removing, inspecting, and installing the rear wheel.

Rear Shock Absorber Service

Procedures for removing and installing the rear shock absorber.

15. ELECTRICAL EQUIPMENT

Electrical System Maintenance

Overview of electrical system maintenance and specifications.

Electrical System Troubleshooting

Diagnostic guide for common electrical system problems.

Battery & Charging System Service

Procedures for battery removal, installation, voltage check, and charging.

Ignition & Starting System Service

Procedures for servicing ignition and starting system components.

Switches & Sensors Service

Procedures for servicing oil level switch, fuel unit, and switches.

16. ELECTRICAL DIAGRAM

Scooter Electrical Diagram

Wiring diagram for the DD 50 scooter's electrical system.

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