how to check pick up coils on xt-250 1984?

Answer 1

You can check the electrical resistance with a multi meter, but I've found that doesn't mean a whole lot. The pick up coils short out internally when they go bad, and at first, they often times work fine when cold but poop out after they warm up.

There's a meterless way to check them. Remove and/or insert another spark plug into the plug wires and lay the metal part of the plug onto the engine. With the ignition turned on, you should be able to take the metal end of a screwdriver and momentarily (quickly) touch and then remove from the little metal tip protruding (towards the crankshaft) from the pickup. When you do, the plug should fire. If it doesn't, it could be either the pickup or the ignition coil. If your engine is multi cylinder and you have two pickups, swap the small wires on the two ignition coils, and then when you touch the pickup, the plug that previously didn't fire should do so and the one that didn't, should.

If you have only one pickup and ignition coil and still don't get any spark, disconnect the two small wires on the ignition coil. Ground one of them (doesn't really matter which one, but usually the black one is grounded) to the frame and momentarily energize the other wire and you should get a spark from the plug. If you're positive of which one is the ground wire, you should be able to leave it attached to the wiring harness.

To energize the other wire, you'll either need to run a wire from the positive battery terminal or, if you have a battery charger, connect its black ground terminal to the negative battery terminal or attach it to the engine or frame. Use the red charger terminal or temporary hot wire to touch the other small wire on the ignition coil for just an instant and you should get a spark. If you don't, then it could be the ignition coil that's bad. Usually an ignition coil causes missing before going completely dead, but not always.