Leopard starting issues

As I posted in IAME starter I have a Leopard 125cc The kart was running in my first session out when I got it ,then wouldn’t turn over getting reedy for my next round, can home and traced the problem to a blown fuse in the powerbox ,replace the fuse. Now it turns over and I have spark at the initial hit of the button and then no spark, let it rest a second and again spark at the first hit and then nothing. Any Ideas?

Suspect that the battery is not up to starting your engine. I’m assuming that the engine is not flooded and the plug is not fouled. Also assuming that you do not have a battery tester. An auto parts store may have one and test your battery. If you have a digital volt meter, disconnect the battery after it you tried to start the engine. It should read at least 12.5 volts.
What is the rating on your battery. If you have one rated at 12v and 7.2 Ah it isn’t strong enough. Batteries like that are more for emergency exit signs than karting. You need a rugged 12v/ 9Ah and a good charger.

Does your engine fire up and run on its own if you use and external starter?

If you are now finding an intermittent spark issue, double check all ground wiring locations.

Is your Leopard a MY09, or earlier model? I’m wonder which electronics version you have. A photo would be even better.

Hi. probably have the same problem. I have the engine iame leopard 125. year 2005. when I hold the green start button, the engine starts, but as soon as I release it, the engine stops. on the pressed button works. relay rather ok.

How are you testing for spark? Listening for sound of Combustion or Grounding the end of Spark Plug Wire to Head?

I ran into an issue with a bad battery. I would charge it fully and it would turn over the engine, but did not have enough power to also fire the ignition. When jumped with another battery, it fired right up. Got a new battery and problem solved.

Like @Dedo said, check all your connections. Grounds, Connectors, Crimps at Connections, etc. A loose wire could play havoc on the Ignition System. Also make sure Plug is not fouled. Once they foul, they will give you trouble every time.

Not as sure about the pre-2009 Leopard. I have a MY-09. It uses a key switch with 3 positions: Off, On and On/Crank. The engine can be started from the On position with the aid of an External Starter. On/Crank trips the Relay to send power to the Onboard Starter.

If yours has only 2 buttons, I would think there is some kind of secondary switch inside the box that after pressing the start button, holds power to the system until the stop button is pushed. Otherwise the system would stay Powered the entire time the battery is connected. On a side note, the Off Button should also interrupt current from the Magneto to the Coil so you can stop the engine. Sounds to me, based on what you are describing, there is a switch in the box that opens (instead of staying closed) when you take you finger off the Start Button and breaking the connection to the Coil, killing the engine. You could test this with a simple test light or volt meter. Connect one end to battery Ground and probe the connections to the Coil. Hold Start button down and see what you get.

voltage is 12.6V. the spark was, now after trying, checking everything, it suddenly disappeared …! I check the spark by touching the engine spark plug. he was starting to walk, but it was going badly. after releasing the start button it went out completely. new fuel. carburetor after service, pop off very good.

Clamp the volt meter to the chassis/engine ground strap coming off the coil and the energized wire powering the coil. When you push the Green Button, you should see about 12.6V. If it goes to 0V when you let go, its a bad Start Button. Should only go to 0V when you press the Red Button.

I do not see a separate Ignition Module in the Wire Diagram. If there is one, it may be built into the Start/Stop box or mechanically triggered by a pickup on the Crank next to Magneto. That would be my only other guess.

I changed the power pack, I used a spare one. the spark is there but it doesn’t even ignite.

I bought a kart a long time ago. undressed. everything is after service. trying to run it but unfortunately nothing.

I see 17.5V . when I released it dropped to 0. the problem is in the power box, but I don’t know which element is wrong.

For those who have their carb off the motor and the motor will start but not run on its own. Removed the carb again and verify the gasket behind the carb is not block the pulse line hole in the block. The pulse line is needed to pump fuel into the carb.

Its ok, because engine starts when the start
bottom is pressed but it stops
when bottom is released. Engine running.

I check everything, I dont why and how, but I lost spark. Its horrible! In my opinion, power pack is damage. On second power pack, spark is weak. Engine can’t fire up. So now i have big problem.

That is strange. Battery voltage should be between 12.6 V and 12.9 V for a Sealed Lead Acid Battery. Are you checking voltage on the Supply or Trigger side of the coil?
One wire to the Coil should Energize it, the other should be a Pulse Trigger to Fire it.

Could be the battery is not fully charged and the act of cranking is dropping the Supply Voltage to the coil. Integrated power system should take over once engine is running. That is why External Starter will work when Battery is no good.

This is definitely a box issue. My suggestion is to use second box and replace the battery if it will not maintain enough amperage to crank and initially power coil.

I checked the coil, taking ground from the frame, and the signal from the coil power cable. this cable was connected to the coil.

On second box, engine still don’t want running. Spark is weak.
And when the starter spins on the second box, it makes a different sound than on the first. does not work smoothly only sometimes stops and interrupts.

Were you, are you able to apply throttle while you were recording the video? Does applying throttle while trying to start help.
I wouldn’t rely on the engine starting and idling on its own at start-up without having to use some throttle input.

Also, if the battery is weak it is effecting the cranking RPM. This my cause a weak spark. If you have a voltmeter, measure the voltage drop across the battery terminals while you are cranking the engine. Do this with the spark plug wire removed from the spark plug. That’ll keep the starter engage to the engine without a chance of the engine starting. Document the voltage at the battery terminals without cranking, and again while cranking. The difference is your voltage drop.

I recommend you ground the end of the spark plug wire if not attached to the spark plug or you could damage the coil.

Spark is generated by Coil and Magneto, so it should not become weaker with at different box unless there is a grounding issue in the box or somewhere else on the wire harness. You may want to remove and sand clean all the grounding points (bare bright metal). I am assuming you are only swapping boxes (unplugging one and plugging in another) not swapping the wire harnesses.

@MichaelPOL Do you know anyone that has an external handheld starter? If you could borrow and get someone with one of those, you could use it to start the engine and also evaluate spark. The battery IS NOT needed to run the engine.

I swap boxes with completly wire harnesses.

I don’t know anyone ho have handheld starter

The 2 cycle is such a simple thing, if it has spark, if it’s getting fuel and it has compression, it’s going to run. If it’s not running, those 3 things are all that can cause it not to run.