TOPIC: No start puzzle

I hope my Four Winds friends will forgive me for posting about a KLR.

This has got me stumped. My 2003 KLR can be very difficult to start once it warms up. It starts easily when cold (with a little choke), and runs well at all times, as long as I don't shut down.

I suspected a leaking float needle causing flooding. Replaced the needle, adjusted float level, and verified correct fuel level in bowl using a clear tube attached to the carb drain. No joy. Main and pilot jets were both cleaned (not needed) while the float bowl was off.

Now here is something I discovered yesterday that has me scratching my head. Even though it sometimes won't start at all (when hot) with the electric starter, I can push start it easily every time. The obvious explanation is that the the power draw from the starter doesn't leave enough juice for ignition, right? WRONG! On the first generation KLRs, the ignition system is isolated from the battery and starter. I can't explain why it starts first time every time when the rear wheel turns the engine over, but not when the starter does. Weird.

Any ideas?

Frank

It sounds like something is going on when the bike's hot that doesn't bother it when cold...which, if the carb is clean so the bike's getting fuel, might indicate too much fuel when hot? I.e. Flooding? ...Just a thought... If you have plenty of spark when the engine's hot, it would appear the trouble may well lie with the fuel system. If pushing the bike starts it, but the starter won't when hot, is there any connection on a KLR between the electrical system and fuel system? A fuel pump maybe? Just some thoughts.

Hi, Ralph.

Thanks for the reply.

The no-start-when-hot problem was cured by replacing the spark plug. The one that came out only had a couple of thousand miles on it.

Why the bike would push start easily but not start with the electric starter remains a mystery. There is no connection between the fuel system and electrical system. The only connection between the ignition system and the rest of the electrical system is one wire to the CDI that is powered when the starter button is pressed. Its purpose seems to be undocumented, but my guess is that it signals the CDI to retard the timing a few degrees when the starter button is pressed. Disconnecting that wire had no effect on the no-start condition.

Flooding was my first thought, but when I discovered that I could easily push start the bike, I started looking elsewhere.

Frank

That's interesting, Frank. Makes one wonder what about the old plug when at operating temperature would cause the bike to refuse to start via the starter, but would allow it to start by being pushed...unless by the time trying to use the starter and giving up, the plug had cooled sufficiently to fire properly when the bike was pushed. On the other hand, if, after enough non-starting one simply immediately pushed the bike to start it and it would start it wouldn't appear to be the heat, necessarily. Curious indeed! ...'Tis a mystery!

Hi Frank -

I haven't visited the forum in awhile otherwise I would have posted sooner. It appears you have resolved your issue with a new plug already. I have no idea why replacing the plug would have solved the issue other then possible hairline crack in plug isolator that expands when hot??? Still doesn't make sense that it would bump start fine with same plug? Did the magic button spin the starter same as when cold when hot or was it slower?

Don

That, Don, was my puzzlement too... Why would the bike bump start when hot, but not electrical start...and why would changing the plug cure the problem? It would appear to have something to do with the plug, but what? A short while hot should have made it equally hard to start whether with the starter, or bumping it... Though one curious possibility could have been a short that would render the plug unsparkable with a slightly lowered voltage when the starter was drawing current, which lowered voltage might not be there when bump starting...only thing I can imagine would cause the problem. Be interesting to know for sure!