How to repair a scooter at home - Scooter not starting.

Scooter repair guidebook

Before “starting”, let’s make sure you are not ignoring most basic things.

Because sometimes we forget simple things.

1. New Fuel is available in tank & holding left brake lever while pressing start switch.

2. Engine oil - No engine oil(even a small leak will drain whole engine oil in a period of few months), oil filled more than needed, less oil, dark brown or black colored engine oil etc. are common reasons of trouble in starting.

3. No fuse is blown. Have a look at the service book and locate the fuse box.

Usually these are located in a very accessible place. Then make sure that no fuse(charging main fuse, main fuse etc.) is burned.

Ultimate step-by-step guide to troubleshoot and repair a motor scooter/bike that won’t start.

When kick-starting, if you only hear the sound of mechanical parts moving, it means No ignition is there. Sound of mechanical parts moving only means there is no explosion sound.

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Scooter not starting and no sign of ignition is normal in cold weather.

1. Case 1 - Only mechanical parts moving sound(with compression). This sound will be similar to when we try to kick without turning on the key. Engine crankshaft & other parts are moving, but no ignition.

2. Case 2 - One or two power stroke sound and stopping. This sound can be identified as Deep “Teih, Teih” sound.

3. Case 3 - No compression. In this case, there is no ignition or compression. In this case kicker will be loose, and there will be no compression.

Means air pressure is loosing through some leaks. For example, we take spark plugs out of engine & turn motor over there will be no compression.

Case - Sound Sample - No ignition while kick-starting.

Case 2 - Sound sample - Engine starts but suddenly shuts off.

It is a bit difficult to differentiate this sound when starting with a starter motor.

But even with starter motor sound, the explosive sound of engine starting can be easily identified.

Scooter not starting - troubleshooting step by step.

First 3 things what mechanics check when a motor scooter is not starting are Fuel, Engine oil & spark(Spark plug).

Case 1- No ignition while kick-starting.

• Step 1 - Common reason for ignition system not working is spark plug. So remove spark plug from engine & inspect it.

• Step 2 - If spark plug is in good condition, check battery. If the brake light is not turning on, the battery is dead. While some scooters will start and run even without a battery, some ignition system will not work without a battery. If this is the case, try jump-starting it.

• Step 3 - Ignition coil in another important part of ignition system. Ignition coil is what provide very high voltage to spark plug.

• Step 4 - CDI unit is the brain of ignition system in most low-end motor scooters. There are 2 types of CDI systems, AC CDI & DC CDI. Here is how to spot and repair a CDI Unit.

• Step 5 - Regulator & rectifier is another part of ignition system in scooters, but these parts rarely get defective. You need to check this if scooter self-starter is not working, but scooter starts with kick-start.

• Step 6 - Check for Starter relay problems.

• Step 7 - Magnetic coil in engine, create current for charging battery and also for lights.

Case 2 - Engine starts but suddenly shuts off.

This is better than case one, because in this case the engine is working. Engine will shut off because of many reasons. Following are some step-by-step guide to figure out its problem.

• Step 1 - In this case also, remove spark plug from engine and inspect it. Make sure that spark is bright blue/ strong white, It is hitting at the center of spark plug center electrode. Clean or replace it.

• Step 2 - Make sure engine oil is in good condition & right amount. It should not be too dark. Do the finger test(take a drop of oil between thumb and index finger and move fingers apart. If the oil break between fingers very fast viscosity is low) on engine oil to understand its viscosity.

Other way to determine oil quality is taking a drop of oil in a finger and wiping it off. If dark color still exist inside the fingerprints then oil is bad.

• Step 3 - Clean and tune carburetor, dirty or clogged carburetor is one of the main reasons of this problem.

• Step 4 - Recharge or replace battery if dead. Try to jump start it with other battery.

• Step 5 - Make sure engine compression is there.

• Step 6 - Clean & replace air filter.

• Step 7 - Check for Engine spark timing(this will also cause compression loss)problems (Very low chance of this happening).

Case 3 - No Compression from scooter/bike engine

Loss of compression from engine can happen because of leak in valves, broken parts, defective engine head gasket, problem with timing belt etc. Or there is a hole in piston.

• Step 1 - Do a compression test. If sure about no compression avoid this step. You can do a DIY compression test by removing the spark plug and putting your thumb(closing the spark plug hole) on top of the hole. Kick the scooter and if your thump is pushed by the engine then compression is there. It is not the best way to test compression, but it is easy & quick way to test compression.

• Step 2 - No compression is a major problem with engine(Kind of). So if you are trying to repair it by yourself, open engine head & check for issues. This can be done without removing engine completely.