Clutch snatching Madass 125cc

A snatching clutch is the most likely reason, or a dirty carburetor.

Lots of help in the link

https://www.google.com/search?q=engine+runs+fine+until+I+engage+the+mowing+deck

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Clutches do wear out eventually especially if you 'slip' it regularly. First check the basics. These are usually the quickest, cheapest fixes.
Check it isn't something between the lever and gearbox 'sticking'. Sometime trail dirt can get into the levers and cables gumming everything up.
Do this with the engine OFF and the keys OUT.
If you can, remove the clutch cable from one end. Work the lever on the handle bar to see if it moves freely. Slide the cable backwards and forwards through it's sleeve to see if it slides easily. Next work the lever on the actual gearbox. This might be stiff but it should move smoothly and return to it rest position every time. If these all move freely the issue could be the clutch plates inside the gearbox.
Next pull the clutch in, start the bike, and put it into first gear. Only give it enough throttle to stop it stalling. Gently and slowly let the clutch out and feel to see if the bike rises evenly with the lever or grabs and lurches forward.
If it lurches and the levers and cables move freely you might need to replace the clutch components.

as per your description problem not clutch since able to start in gear and drive without stall problem sounds more like a fuel delivery not the clutch

Replace the Torque Converter Solenoid in
the transaxle

What you have is like coming to a stop with
a manual shift & not pushing in the clutch & it stalls
the motor

The converter clutch is staying locked & your
trans is connected to the motor

Back wheels often move when the lever is pulled in...this is due to hydraulic drag caused by the oil on the clutch plates and is totally normal. You should be able to stop the wheel by hand with the lever in.
With the lever out the clutch is fully engaged and the engine will therefore stall with the brake on...
As long as the wheel rotation can be stopped by hand with the clutch pulled in it's behaving normally...
Rocking the bike in gear is a method that's used to seperate the plates on a clutch that is dragging...usually if it's not been used for a while.

Check that the clutch is in, kick stand up, and neutral light ablaze. Then try your start button. When you had it running and hit the button, the starter engaged at a slower speed then the bike engine was turning, which led to the stall. The stall means your starter works. If the starter works when the engine is running then it is wiring. Check your kick stand wiring along with the clutch wires which plug in on the handlle bar or where the clutch cable enters the engine.

Hi and welcome to FixYa,

Initially, if the bike will be run without its own battery, the engine will really stall. This is because there will be no consumer for the voltage output other than the ignition system which will clamp down when the engine is revved and the voltage tends to go higher still.

Just a start, do postback how things turned up or should you need additional information. Good luck and Thank you for using FixYa.

sounds like the throttle cables need to be looked over .( he get everything back to where it was before the lubing?)as one may be out of sync with the other. the oil change has NOTHING to do with the sputtering and surging ,stall .it would only apply if the clutch was slipping and that would make the bike rev with the car oil.