Reply To: Gt125 Comet will not start
This is the process of the bike to get sparks and start it.
Key On
Press Start Button
CDI checks rider has held in the clutch lever = Make sure switch is OK or replace it.
CDI checks the neutral light is on = Make sure rear wheel is actually freely moving, since fake neutrals are rare but do happen some odd cases.
CDI checks side side stand switch = bypass this unit, remember what was said in previous comments above from myself and Simon
Now the Solenoid (Starter Relay) clicks to initiate the power to the starter motor to spin it & crank engine.
A bad solenoid or a bad starter motor will make the sparks weak.
Why? They are straining the battery in excess
As the engine starts spinning (cranking)
The “STATOR UNIT” tell the cdi how many revs it’s doing
(Hint, the rpm gauge will be bouncing 600 rpm as bike turns over)
Now the “STATOR UNIT” will also tell the cdi how much to spark
The CDI unit, then tells the coils to charge up & fire up 10,000 volts down the HT caps to fire the plugs
You will not see sparks or they will be very dull, if
– Coils are shot
– HT Caps are shot
– Battery is too old (volts dropping)
– Battery is too weak (AMPS aka Cold Cranking Amps isn’t sufficient to crank and power up the bike, electrics etc while engine is cold cranking)
– Plugs have given up (Replace them)
Once the plugs are sparking , the engine comes to life thanks to the pistons drawing fuel out of the carbs and creating vacuum for the tank taps & fuel pump to keep the fuel supply going.
If the clutch lever switch acts weird while bike is running, then it will cut the sparks off almost instantly or when dropping to 1st gear.
If any parts above ^ that were involved in starting the bike act funny while its running, the cdi cuts its sparks off.
If compression is WEAK, it will be hard to start.
If valve clearances are “too tight” or “too lose”, it will be hard to start.
But let’s cross this bridge if all electrics are sorted out first and its still not starting but i do pray the engine itself is OK.
Also, try this when it is safe to do so please.
Make the bike ready and connect everything and make sure battery is fully charged. Find a private road. Sit on the bike , and have someone push you till you get 10mph on the dash (jogging speed-ish) , then drop to 1st gear , have choke on. and be ready to twist the throttle to scream it to life.
If it starts by “pushing” the bike , then let us know. Don’t jump start a bike with jump leads with a live running van or car as they will 100% burn the electrics of the bikes.