Motorcycle Repair: 1975 Honda XL250K2

Question
Hi Bill,
I recently restored a 1975 Honda XL250K2, and it looks and runs great... Most of the time!
On rare occasions, while riding on the street, the bike will start to sputter and die. This has happened twice on level roads, and the bike starts again after a couple of kicks... Neutral light still works when the bike dies, so I don't think it's an electrical problem, but since it's so intermittent, I don't know how to diagnose it.
Any ideas?
Rick

Answer
Richard, if the bike starts back up right away, it is probably fuel related, not electrical.
XL250s have an ET ignition which runs without a battery, as I recall, so unless your points are a little dirty or you have a loose electrical connection, that is probably not the area of issues.

Check the gas cap for blocked vent holes and or a gasket that covers them up. When the tank can't breathe the gas gets locked in a vacuum and the bike can run out of fuel before the tank can resupply the float bowl.

If you can catch it when it stalls, try to shut off the petcock immediately and drop the float bowl to see if you have sufficient fuel or not. If not, then either the cap vent is blocked or there are other fuel supply issues in the fuel filter, or fuel lines/float bowl. Check the float bowl for any signs of fuel contamination, like separated gas/alcohol from gas which is been sitting for more than a couple of weeks.

You might want to go over your tune-up, checking valve clearances, ignition timing and fuel system cleanliness after the restoration. New points will close down in the first few hundred miles causing retarded ignition timing, which affects the fuel metering in the carburetor.

Bill Silver