...................................Kymco scooters do seem to disproportionately suffer from starter relay issues and that could be what you're experiencing.
Thanks for your comment. By having a close look at the starting problem above, your comment (quoted above) reminded me about a similar problem we experienced quite some time on some engines at work before I retired.
I short - for almost two decades I was involved in building industrial High Pressure and drain cleaning machines for local municipalities and private companies. On certain engines we experienced similar starting problems - as described above. Engine quality was good, but we kept on having come-backs with starting problems. The symptoms were exactly the same as described above.
After a proper investigation at work, we discovered that the starter solenoids on the engines actually needed a separate relay just before the starter relay. The reasons were very simple:
1.The engines came from the manufacturer with wiring which were too thin for starting purposes.
2. Voltage tests at the starter solenoids proved that there was a substantial Voltage drop at the starter Solenoid whenever we hit the starter button.
In short - the problem has been solved permanently just by installing ordinary 4-pin Relays just before, and quite close to the starter Solenoids.
The reasoning for this modification was as follows:
1. The "switch part" of an ordinary Relay ( terminals 86 and 85 ) only draws low Amps to activate the relay Switch.
2. Terminal 30 on a Relay usually gets connected directly to the Battery, with a fuse in between.
Terminal 87 on a 4 pin Relay is the " Positive Power Supply) to whatever component needs proper power supply.
So this is what actually happens when a Relay gets installed:
1. When the Starter Button gets pressed, the "switch part" (86 and 85) of the Relay never pull much Amps, and the switch can even cope with a voltage drop to get activated.
But important:2. When the switch part get activated, the solenoid actually gets proper Volt feed
directly from the Battery - via terminal 30, and the starter motor draws proper
proper Volt feed from terminal 87.
This means whenever an additional Relay gets installed, the starter Solenoid does not get a voltage feed via the starter Button any longer - the Solenoid actually draws
proper Voltage directly from the battery.
Modifications like this also protects the starter buttons, as well as solenoids itself. Since we started doing this modifications at work, all starting problems disappeared and we never had any come-backs again.
To my mind the starter button on my scooter is probably not suitable to handle the Voltage feed to the starter Solenoid for too many years. The wiring to the Solenoid is also quite thin and although I haven't done a Voltage test at the Solenoid, I am absolutely convinced that these scooters
will have a substantial Voltage drop at the starter Solenoid.
Although I have not experienced any similar starting problems yet, I am absolutely convinced that a Relay medication as described above can only have benefits on these scooters. Therefore I decided to do a similar modification on my scooter - just to try and expand the lifespan of the starter Button and Solenoid on my scooter.
If anyone might be interested, this is a drawing of how to install a separate 4 - Pin Relay to ensure proper Voltage feed to a starter Solenoid / Starter motor:
