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...but we can't find what's wrong with this '07 KLR 650 with only 5k miles.

It DID sit for a year with 900 miles on the odometer before my husband bought it this January, but it was running great for months and months and then it just stalled out a couple weeks ago and wouldn't start. Neither he nor I is a complete slouch at home-wrenching, and we've both done all we know to do.

After he pushed it home, we emptied the tank and put in fresh gasoline (had just been to TN where water in the gas is more common.) Then we pulled the carbs and he cleaned them twice, and I cleaned them again, finding a barely bad float valve needle, which we replaced. The lines are clean, the vacuum is good, the carb is in great shape, no kinks in the fuel lines. The air filter is clean (stock). There is good spark. But it still won't idle without the choke on, and it stumbles badly. Adjusting the idle screw doesn't help. Opening the fill hole on the tank doesn't help. There are no intake leaks that we can find, it's basically a new bike with nice clean supple boots and air box fittings. Re-gapped the plugs, disconnected the coils and cleaned the terminals--no love.

This should be the idle circuit in the carb, right? I've been through it with carb cleaner and lots of compressed air, we have the manual so I was able to make sure it was flowing right. I polished the seat of the float valve needle, checked the diaphragms (including the vacuum diaphragm). Nothing has happened to the bike, hasn't been dropped or abused. It just sat for a long time between when the original owner scared himself and when the hubby traded the Harley for it (hooray!) back in January.

Could a low-miles, new bike be having timing problems? Could it really be a CDI? It revs up fine, but it won't idle. It's a fast stumble for as long as the choke is on. It backfires through the exhaust a little if you rev it, with the choke on. When you turn off the choke it sputters out and dies very quickly.

I would swear the carbs are not clean enough. But I put the cleaner to it and saw it shooting out the appropriate end of the idle circuit myself. Is it still dirty? And if so, then what can I do to clean it more?

We'd appreciate any information, the poor fellow dearly loves the bike and hasn't ridden it in weeks. I've rebuilt several four-cylinder racks of carbs but this little single is kicking my butt, too. Thanks for anything ya got....

Well you covered the stuff it should be, so it may be time to look at the possible-but-unlikely.....

I'd have a really good re-check of the carb diaphram, just to be sure...

and re-blow the idle circuit, both directions if possible. and maybe give it a gentle scrub with some sort of soft pokey device, like heavy fishing line or a floorbrush bristle, while blowing..... if possible.

It could be the CDI, but usually they fail completely or in the upper RPM's, but not always.....

Does the idle adjustment just set cable pull or is there a tapered screw that limits the actual slide height?

The fact that it 'just happened' to a newer bike sounds like something failed or clogged, not went out of adjustment. The timing is not really adjustable, but pull the ignition cover and make sure a hold down screw didn't back out.

I'm out of ideas......... uuuhhh, sorry?

I'm with Buzzz on this one. Sounds like something failed on it.

I'm assuming (knowing that you've rebuilt lots of stuff) that you've checked spark and compression. Only thing I can suggest is to crank it over holding a paper towel over the spark plug hole and see if you get fuel on it (choke off).

After that I'd say either your pilot circuit got something big jammed in there or the CDI box failed.

OK he's here and just read the thread, we know what to try next. Our other mechanic buddy also says the sudden onset of the trouble likely means the idle circuit is clogged, but also suggests checking the intake valve. He's been wrenching since before I was born, he said at this many miles, the intake valve, if it's off far enough, can cause this kind of erratic running.

So...pull the carbs and stick one of my violin bow hairs backwards through the circuit and push it along with carb cleaner...and a 5k mile valve check.

Can do...

Thanks folks, I know you two will always offer good advice.....

Wrider I'm goin' to CO!!!!

Hope it works out for you. Since I once had a problem like yours on a set of Kaw Z-1 carbs in the 80s, I've sworn by fishing line through the idle passages. Like you, I went through the carbs several times, but it turned out that there was a gob of gunk that just wasn't coming out with compressed air. It took some flossing with the fishing line to break it up enough to be blown out.

Best of luck!

You'd better come out! Can't wait to meet ya!

...doing valves. Intake is within spec, but exhaust is very tight.

Had my buddy the old wrench look behind me, he adjusted the float level and pronounced the idle circuit as clean as he can see it. We'll get the right shims in there since it needs to be done anyway, and then if it doesn't help we'll go back to the carb....

clean your carbs properly and dip them, shots of carb cleaner doesn't do the job!

I fixed the KLR!

The bike hadn't run since July, bad idle still, we tried everything but nothing helped.
Husband David finally got work, it's temporary but hey anything these days is good....

So it was a good time for me to tackle the bike myself. I went behind him and tested everything in the Clymers, buttoned it all back up, still no idle.
Then I got a compression tester to see if maybe it was a bent valve. But when I took out the spark plug it had almost no gap and the terminal was bent all up. Re-gapping it didn't help, I think it burned out. David said he gapped and installed a new plug months ago?...?

I snatched a plug out of my faithful CB750 (same kind) and gapped it and installed it and WENT FOR A RIDE ON HUBBY'S BIKE! It's running great and idling just fine. It was sitting in the driveway waiting for David to come home and take a ride on it when he got home last night.

He is properly chagrined at missing something so simple, and swears he gapped and installed a new plug, but I'm just happy to see him back on the bike. He missed it so much, he really likes that KLR!





AND, I have earned MAJOR "marital rewards" points....






If the emoticons worked I'd be having a field day right now.....