A few days ago to repair a Dayan DY100 motorcycle, according to the owner of the description, he this car cold start is unusually difficult, before the maintenance of the master suspected carburetor problems, suggested that he replaced the new carburetor, but the fault still exists, and did not use much.

After picking up the car, first test run, open the key switch, press the start button to try to start, feel the starter is very strong, battery power is also ok, but the starter runs, the engine is not started, even no signs of fire.

Continuous start, toss for a long time, the engine finally started fire, the car is really difficult to start the cold car, if it is started by feet, it must be tired out in a sweat.

Since the car can finally start, and start the operation is good, and the carburetor has been replaced not long ago, it can first rule out the oil circuit problems caused by the difficult to start.

It should be the engine ignition system, ignition timing, gas timing, gas phase inspection, these are also leading to some unpredictable factors that are difficult to start the vehicle.

Unplug the high voltage line, unscrew the high pressure cap, and test the fire against the cylinder block. When starting, the spark is bright, and the ignition energy is enough to ignite the mixture. Preliminary inspection shows that the technical status of the ignition system is good.

Take a socket wrench and slowly turn the magneto rotor in the normal rotation direction of the magneto rotor. Align the top TDC mark "T" on the magneto rotor with the timing mark of the engine viewing hole to check the timing.

It was confirmed by inspection that the "O" timing mark on the camshaft timing drive sprocket was aligned with the cylinder head timing mark, indicating that the engine timing was also correct. At the same time, check and adjust the inlet and exhaust valve foot clearance, so that it is in the best working state.

The next step is to check whether the valve phase is normal, how to check? The method is as follows:

Continue to rotate the magneto rotor slowly with a socket wrench, and closely observe the action changes of the inlet valve rocker arm. When the inlet valve rocker arm pushes down the inlet valve stroke by 1mm, that is, when the inlet valve is opened by 1mm stroke, stop rotating the magneto rotor immediately and keep the original position unchanged. Observe whether the timing mark of the engine viewing hole is aligned with the top dead center "T" mark on the magneto rotor. If aligned, the engine valve phase is correct.

No obvious abnormality was found in the inspection of the above mechanical parts, so we have entered a tangled area. What is the reason that makes the engine so difficult to start?

We reviewed the troubleshooting again, looking for missing parts and clues, and we found nothing, which is strange, based on our experience.

But also found in the inspection, three wheel motorcycle battery negative grounding wire is fastened on the frame, not directly connected with the engine body, electrical circuit grounding wire is through the frame and the engine communication electrical circuit.

In motorcycle electrical equipment, the working voltage output by the trigger winding is the lowest, the working current is the smallest, if the contact resistance in the electrical circuit increases, it has the greatest influence on the normal operation of the trigger winding.

The grounding circuit of the ignition system, one is through the public grounding line in the electrical line, the other is through the battery grounding line. Due to a variety of reasons, the three-wheel motorcycle frame is not a very good conductor, if there is an increase in the resistance of the grounding line of the electrical system, it will affect the normal work of the motorcycle electrical equipment.

The normal operation of the light ignition system is affected, and even the electric starting device cannot work properly.

After the analysis of this principle, according to the experience of the article, the battery grounding wire and a direct connection to the engine body, to ensure that the electrical circuit grounding wire unblocked. Turn on the ignition, press the start button, and the engine starts easily. It turns out that the failure is indeed similar.

After a few days of phone inquiry, the owner said that now every day the first ride is ready to start, thank me very much to help him solve this troubled problem for a long time, confirm that the fault has indeed been eliminated.