It starts then stalls immediately on a Kawasaki ER-6n 2016

Clogged jets / idle circuit

Diagnosis confirmed: the idle jet (also called the pilot/slow jet) is clogged. This is the circuit that feeds the engine at small throttle openings; it has a tiny calibrated passage that's especially prone to deposits. The classic cause is winter storage: fuel left sitting in the float bowl evaporates and leaves behind varnish and residue that block this small passage. Typical symptom: the engine starts and holds up fine when you blip the throttle (the main circuit is working), but won't hold an idle and stalls as soon as you let off the gas, or starts and immediately dies. The fix: remove the float bowl, take out the idle jet, clean it thoroughly (the tiny passage needs to be fully clear), and clean the whole bowl and passages while you're in there. This is an intermediate-level job, manageable for a careful home mechanic. Safety: fuel is flammable, work in a ventilated space, away from any flame. Risk level: moderate. Cost: a can of carb cleaner (around 10 euros), a float bowl gasket kit (15 to 40 euros) if you replace the gaskets on reassembly; a fuel system cleaner additive helps as prevention for a few euros. Golden rule: never poke a jet clear with a piece of wire, you'll enlarge its calibrated size and throw off the fuel metering permanently -- use cleaner and compressed air instead. If several circuits are gunked up, a full carburetor cleaning is called for. This tool helps you understand what's going on -- it doesn't replace a certified mechanic.

How to make the repair yourself

🟡 Intermediate level: a few basic tools and a bit of method are all you need. Work with a cold engine, take your time, and don't hesitate to stop the moment you're unsure.

1. 1Work with the engine cold, in a ventilated space, away from any flame. Close the fuel tap (OFF position) if your bike has one.
2. 2Get access to the carburetor (removing the seat, tank, or covers as needed). Place a container under the bowl, unscrew the drain screw to empty the fuel, then remove the float bowl (screws or clips).
3. 3Locate the idle jet: it's the smallest one, distinct from the main jet. Note its position and size (a number is stamped on it) so you can refit it exactly. Unscrew it gently with a well-fitting screwdriver so you don't damage its slot.
4. 4Hold the jet up to the light: the tiny central passage should let light through. If it's blocked, you won't see any light through it.
5. 5Clean the jet with carb cleaner, then blow compressed air through the passage until it's completely clear. NEVER use a piece of wire: you'll enlarge the calibrated size and throw off the carburetion for good.
6. 6While you're in there, clean the whole float bowl, the passages, the main jet, and the channels with carb cleaner and compressed air: idle jet clogging usually comes with other deposits too.
7. 7Refit the idle jet, reinstall the bowl with a gasket in good shape (replace it if it's hardened), close the drain screw, reopen the fuel supply, and check for leaks.
8. 8Start the engine, let it warm up, and adjust the idle if needed: it should now hold a stable idle without stalling. As prevention, drain the float bowl before winter storage and use fresh fuel.