Ktm problems

When a bike is running at a good rpm and dies like somebody threw a switch, it means something is badly wrong. As an old mechanic once told me, an internal combustion engine runs on air, fuel, and fire, plus compression. I've never seen a bike stop running because of air supply, so it's not that. And they don't stop suddenly from a fuel failure; more likely, it would have done a panic-rev as the fuel supply dried up. So it's not fuel. That leaves spark and compression, and either one will cause a sudden failure. Is the bike excessively easy to kick over? If so, you've lost compression and will have to rebuild the top end or the valves. If compression seems good, pull the plug out and attach the lead wire. Ground the plug on the engine head and kick it over in the dark. You should see a hot spark. If no spark, you need to test the stator, the pulse pickup, and the coil. One of those is probably bad; that happens to KTMs sometimes. Hint: check your spark plug lead wire first, though, to make sure it's not broken. That's a cheap fix.

Check all your electrical connections and make sure there is no dirt in any of them. That would be my 1st idea.

Maybe check the kill switch to make sure its not killing the motor ie grounding out the ignition.

From there its on to the CDI and stator. The stator is inside the flywheel inside the motor. But you should be able to test that via the leads coming out of the motor. IF you know someone else that has the same bike you can compare stator output readings to see if you have a bad stator.

It could be the coil. I've seen the go bad on ktm 4Ts before.

Have you pulled the stator cover off yet and checked for water, loose wires? Did you check the primary and secondary sides of the coil? Not sure but is there a resistor in the plug wire cap? Check that if so. Getting a book may help with your troubleshooting. If it gets deep you'll need to know which leads to check the pulser coil, CDI, charge coil, etc. You may only be able to check resistance readings unless you vae a multimeter with peak V output. I'm just guessing since I don't work on katoomers.

Check the plug wire connection at the plug cap. The wire is pushed into the cap (not glued). Very easy to loose that connection. Check both ends.