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Discussion Starter #1
The last couple days, the KLR has backfired loud as hell when starting up in the morning. Sometimes more than once. I start it full choke, don't touch anything but the starter button like I always have. This morning it backfired twice, and then it was wanting to die. Needle wavering between 1K and 3K rpms for about ten seconds. Once it is running, no problem. Before I mess with the mixture or spark plugs or anything complicated, any thoughts?

This happens on and off. Usually when we get the cold, crud weather.

The only thing I can think is maybe I need to readjust the idle mixture screw or the wet, damp weather is upsetting her. It has been raining every day lately and the bike lives (covered) outside. Or maybe I need to start turning the petcock off after every ride? Usually, I leave it on unless it is going to be more than a few days.

Any ideas that don't require me sitting in the cold for a long time? ;)
 

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Discussion Starter #2
Oh yeah. After I tried starting it and shut it off the ol gas cap was whistling. It's not hot, but the tank was pretty full. I have no idea if this would make a difference, but I believe in full disclosure. ;)
 

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Backfiring "usually" means lean fuel mixture. Second could be unburned fuel in the pipe and lighting off.

the whisteling of the cap happens first off when you start and shut-off first thing in the morning?

Your not filling up past the first lip in the tank neck are you?

I'd double check the idle-mix screw and make sure it's out the required amount.. ( I dont remember what that is now.. 2.5-3.5 turns?) and while your at it. pull the seat and side panels and check the fuelline and C.A.R.B. hoses for a pinch or kink somewhere.

I've been out of the bike for awhile now... it's all starting to come back to me ...slowly..:46:
 

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Discussion Starter #4 (Edited)
Backfiring "usually" means lean fuel mixture. Second could be unburned fuel in the pipe and lighting off.

I was thinking unburned fuel might be the culprit. It's so sporadic. And it's only in the morning really.

the whisteling of the cap happens first off when you start and shut-off first thing in the morning?

Yeah, that was just this morning though. It whistles for sure on hot days. I don't overfill. That's why it struck me as so weird that it would whistle on a cold morning???

Your not filling up past the first lip in the tank neck are you?

No.

I'd double check the idle-mix screw and make sure it's out the required amount.. ( I dont remember what that is now.. 2.5-3.5 turns?) and while your at it. pull the seat and side panels and check the fuelline and C.A.R.B. hoses for a pinch or kink somewhere.

Sigh. That's what I figure, too. I was just hoping someone had a magic cure so I could go fishing today. ;)

I've been out of the bike for awhile now... it's all starting to come back to me ...slowly..:46:
Welcome back. To the forum, too. I was wondering if you got ate by one of them Petaluma lunkers. ;)
 

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Dan -

Just for gigles and grins, drain the carb bowl. It will take you but a minute and then you can be sure you've got no water in the bottom of the bowl.

It might be unburnt fuel in the pipe, so maybe you're getting it overly rich on the cold, cruddy, typical San Francisco morning - will it start at half choke?

Kinda warm and sunny here in LA...

Tom
 

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Double A did the 22 cent mod on his KLR last spring and while it ran pretty good for the first couple rides, it started backfiring at startup. We changed the plug and it was OK for a short while and then started again, as well as starting hard.

We un-did the 22 cent mod, changed the plug and that's the way it's been since, and has run perfectly, too.

What's good for one bike doesn't mean it'll be the same for the next, even though they're the same bike.. Double A's and my bike have the same plug, air cleaner, and carb settings, and my bike will start without a choke as long as the bike's even just remotely warmed up, where his requires a choke most of the time. He also gets 6-8mpg better fuel mileage than I do. The only difference is that his is a '98 and mine's a '02.. Other than that, they're identical..

Saying that, just because the 22 cent mod works well for other bikes, doesn't mean your's requires it.

Have you done this to your bike? I'd change the plug, first..
 

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the choke doesnt really choke it down... like the old auto carbs. It just opens an enrichment circuit to add fuel and incorporate a high idle.

Good Idea on draining the carb Tom.
 

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the choke doesnt really choke it down... like the old auto carbs. It just opens an enrichment circuit to add fuel and incorporate a high idle.

Good Idea on draining the carb Tom.
I know, but "idle enrichment circuit" doesn't roll as trippingly off the tongue as "choke".

If I'm getting this right, Dan's bike, which I believe has the 22 cent mod done, was running great until the weather turned wet and cold. He has also recently played with plugs and had an adventure thereby, so his plug is new.

What it seems like to me is that the choke enrichment circuit in full enrichment position is too rich for...

Aw crap, let's just say full choke is too rich for the damp conditions.There's unburnt fuel in the pipe, which ignites, causing an after-fire(s). Then it tries to settle in, as it warms up, with too rich a mixture and the idle hunts up and down.

Maybe half to three quarter choke would make all that go away.

Tom
 

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If i havent started my KLR for any amount of time.. not to mention every morning when I ride daily. I pull the choke on... hit the starter and immediately turn it down so I'm Idling it around 2,000 rpm.or there abouts so it's just running smoothly. winter /summer. dry/wet.
I've never had it backfire. both with and without the 22cent mod.
It currently is back to stock. it's been sitting for 3 weeks. I just started it like I always do.
no backfire.

Undo what ever you have done last. see if it changes .

thats all I got .:63a:
 

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Discussion Starter #10
Thanks for all the responses guys. OK, so I did the KLX needle kit a year ago or so and it ran fine and has since. I changed to an Iridium spark plug, but that was a ways back, too. I haven't done anything lately except dump some seafoam in the tank.

Tom, I dig what you're thinking about half choke. I'm gonna start there. If that doesn't work I'll drain the carb...I agree, good idea. It has been wet and damp and I live about a block from the bay. And it definitely seems like it is a cold, damp morning issue. So, I'll start with the half choke idea...that makes good sense. One way or another that iridium spark plug is coming out eventually, but one of my neighbors bitched about me working on my bike (in the lease it says I can't apparently), so I can't strip her down.

If lessening the choke doesn't work I guess it's off to Mom in laws house to do some wrenching. Or maybe I'll bring some beer up to Mark or Dave.

Thanks fellas. I decided to forget about it today and took a nice ride on the KLR and took the old Honda out for a spin. Man, at 5K RPM, that 450 has gotta be the prettiest sounding bike I've ever heard.
 

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No...

You need to bring beer, and wrench. It could be the muffler bearings or sumthum, no really... bring beer, oh and Frankie, and I have a score to settle too!!!
 

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Discussion Starter #12
You're on. I'll try to convince the girls. Hopefully the bike will be running fine and we can just drink beer and look at the bikes and grunt. ;)

I gotta check with Karen. I'll hit you up.
 
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