Motorcycle Repair: No start, honda nx250, neutral switches

Question
My 88' Honda NX250 died when I didn't give it enough gas and then wouldn't restart. It happened twice so far. Once when I got to work it wouldn't start.Then five minutes later it started right up. Then on the way home at a stoplight. I had to push start it in a nearby parking lot. When I made it home I turned it off and it started right back up. When it happened I noticed that the light dimmed when I pushed the start button but nothing turned. I could put it in gear and feel the engine turning and all the fluids look good.
??
Alexander

Answer
Alexander, how old is your battery? Failing batteries often will take a "surface charge" which makes them look like 12v batteries, but they don't have a lot of actual current available to run starter motors and other electrical items.
In general, motorcycle batteries last about 2 years.

If the lights go out when you push the starter button there are two possibilities: Dying battery and/or many Honda starter circuits normally dim the headlights during starter motor operation, to allow full current to the starter motor. If there are safety switches in the starter circuit like sidestand switch, clutch lever switch and neutral switches, then if any of those are out of adjustment or not working and preventing starter motor operation. Make sure that the brake light circuits are not triggering the light to stay on all the time.

You could be having some venting problems with the fuel tank cap or other systems that are causing fuel flow issues. You could be having some fuel contamination problems in the float bowl of the carb. Fuel filters could be blocked and draining fuel slowly through them, so that the engine usage is greater than the flow rate needed/supplied by the fuel system.

So,
Check battery for full charge and check to see if it passes a load test.

Check fuel quality and filters/lines for any signs of blockages/restrictions. There is a fuel screen inside the fuel tank on the end of the petcock. Also check the small fuel cup on the end of the petcock for debris, water, rust or dirt.

Check the spark plug for signs of wear or contamination due to oil or excess fuel consumption. The spark plug cap should have about 5k ohms resistance when measured from the end where the plug wire goes to the end where the spark plug connects.

Other random failures like this can be due to improper electrical grounds, loose wiring connections and faulty ignition or KILL switches/connectors.

The engine should have a full tune-up, including valve adjustments, to ensure that you are getting full compression when the engine is HOT or COLD. Valve clearances can tighten up on these engines, reducing compression when the engine is hot, which can make them hard to start, as well.

http://houseofmotorcycles.bikebandit.com/Honda-Motorcycle-NX250-1988/o/m2461#
for reference illustrations.

Bill Silver