KDX220 won't idle when warm

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lemmy
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Post by lemmy »

Ok, I dipped the carb and then blew it out with 90PSI air. Then reassembled and reinstalled with an inline fuel filter (not much room for even a small one). I started the bike and let it idle for about 5 minutes. Then I rode it back in forth in my neighborhood 6 times (about 0.1 mi each way) then let it idle another 5-10 minutes. I thought the problem was fixed. But then out of the blue it started wanting to die. Then I screwed in the idle screw a bit (I didn't have it anywhere near all the way in) and it idled ok after that. I finally shut it off and immediately checked the compression. It was about 150+. I thought that was high, so I released the pressure and did it again and got the same results. And that was with the CEL needle. Air screw about 2 turns out.

Also, it seems to be smoking much more than I remember.
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Post by canyncarvr »

Is there a question?

'..it idled ok after that.'

Sounds good to me. It would NOT have before, right?

Nothing wrong with 150psi. That's a good number.

Sounds like you made it all better!

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Post by lemmy »

Yeah, I have never been able to replicate the not idling at home. Only after riding for a while. So it very well may be fixed. I will have to wait until I ride this weekend. But it may be fixed.
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Post by lemmy »

I starte the bike up today and it was about 70 degrees. It wasn't idling that great even when cold. I had to screw in the idle screw all the way. I let it sit for about an hour and put in a new spark plug and it is idling better now and I am able to back out the idle scew some because it idles too high now. But the thing that I am confused about is the bike is smoking quite a bit now. I ride down the street (0.1 mile) and turn around and I am riding through a cloud of smoke. It never did that before and all I have really done since it wasn't smoking that much is fix the kips, put new o-rings where the exhaust joins the head, dip the carb, and replace the CEK with the CEL needle. After letting it idle for 5-10 minutes spooge is starting to run down the end of the pipe.
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Post by Mr. Wibbens »

One gallon can pretty much last you forever



On my KDX, the warmer the bike gets the less it wants to idle. I remedy this by turning in the idle screw

Just need to remember before starting again when it's cold to turn the idle out or it revs to the sky on start up
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Post by Colorado Mike »

Are you sure the added smoke is not coming from a failed clutch-side crank seal?

Is it possible you doubled the oil in your mix?

You could put the original needle back in and see the effect. It could be the new one isn't the taper you think.

Also less likely, there have been cases of the main jet falling out and the bike still runs, but obviously very rich. I haven't seen that though.
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lemmy
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Post by lemmy »

I went back to the 1173L needle (#2 clip), 152 main and 42 pilot. According to the spreadsheet this leans everywhere compared to what I had except at 0-1/16th throttle and that is much richer. however it seems to be idling better and smoke is less.

how can i tell if i have a failed clutch side crank seal? it would have been a sudden failure because this smoked just started in the last week or two.
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Post by Colorado Mike »

You could do a leak-down test. There are threads on here that explain how to rig up your own tester.

Sounds like you may have solved it with the needle though.
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Post by canyncarvr »

Your transmission oil level should not change over the course of a couple rides. If it does change (assuming you don't have a puddle under the bike after it's sat in the garage for a week), that's a pretty good indication that oil is getting sucked into the crankcase via a bad seal, then 'burned'.

Does your oil level change?

If it's a bad enough leak to cause an obvious smoke problem, you should be able to smell it. Whatever you use in the tranny, it's not going to smell like 2T oil if it comes out the exhaust.

Never jet by spooge. Or smoke. That your bike is dripping out the exhaust is not necessarily a 'too-rich' indication.

My bike idle changes from time to time...I've never figured out why. Fuel quality or a bit of junk somewhere it shouldn't be I suppose, as it doesn't seem related to whether it's hot, cold, or anything else. Sometimes it won't idle reliably even with the idle screw all the way in, most of the time the idle is as solid as a rock all day..hot, cold, or indifferent. It generally idles differently when it's good-n-warmed up than it does when I first start it. ...don't know how that would not to be expected.

A BTW...'cuz there have been mixups before on this board (and took weeks to get sorted out), but we do agree that the idle screw is the black nylon one, right? :wink: You did say you determined the idle screw to be lifting the slide (throttle valve)...I'm just checking.

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Post by canyncarvr »

>|<>QBB<
lemmy wrote:

Consider a CEK vs: a DEK. Both have the same L-1 (42.20mm), but the 'D' needle has a steeper (1'45") slope.

How does that effect the straight section of the needle (keep in mind the straight diameters..the 'E'... are the same, 2.645mm)? Which needle is leaner than the other..and where in the throttle range..and which needle is RICHER than the other...and where?
But with two needles with same L1 and straight section diameter (d1), I would think the needle with more taper (D taper) would have a longer straight section. in other words the taper would begin later on down the needle because it has more taper, it would get to the 2.515 magic number sooner after its taper starts. Since the D would stay straight longer, it would be leaner at this point (1/4-1/2 throttle), after they both hit the 2.515, the D would be richer because it is tapering faster (i.e. getting smaller faster).
I missed this earlier reply altogether.

Absolutely. That you are aware of that is what I was curious about.

The point at the time was simply to get to an understanding of what an L-1 was (it is not the straight section length) and how tapers effect that...that a needle can be more lean than another in one throttle position, and more rich than the same other needle in another.

..the diameter/L-1 code swap notwithstanding. :neutral:

Now...go build your linearly regulated, low ESR capacitated, WHS rectified, krypton radiated power supply.......... :wink:

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Post by Mr. Wibbens »

>|<>QBB<
canyncarvr wrote:
A BTW...'cuz there have been mixups before on this board (and took weeks to get sorted out), but we do agree that the idle screw is the black nylon one, right? :wink: You did say you determined the idle screw to be lifting the slide (throttle valve)...I'm just checking.
Sorry I donut agree!

Mine aint black

Aint nylon neither
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Post by lemmy »

Yeah, the idle screw is the black one :grin:, definitely better to make sure we are talking about the same thing!

Yesterday I started it up and road it in the neighborhood and it didn't smoke that bad. Today, I have changed absolutely nothing. Pull it out and start it up and it is smoking really bad again. However it was idling very high. Warmed up to about 150 degrees and was still idling great. I had to back the screw way out to get it down below 2200 rpms. I guess I will try the leak down test and if that turns up good, I give up.
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Post by lemmy »

I actually went for a ride today. It idled and ran great for a while. It smoked some, but not a really bad amount and the guy behind me said it didn't smoke much at all while riding. I did get a pretty good amount of spooge. Anyway, as usual on the slow technical downhills where I am using engine breaking if I pull in the clutch and it will act like it is going to die. And then from then on on the rest of the ride it doesn't idle well. I get back to the parking lot and I put it in N and let it idle. It is steady at 2500 (maybe it is 1250, but I have the Vapor on the setting that gives me the least rpms and it is still 2500). It idles very steady for about 8-10 seconds and then over 2-3 seconds it will drop from 2500 to about 1000 and start to die if I don't rev it. Then it is steady for 8-10 and drops again. I finally turn off the gas and it idles fine and the rpms slowly started to rise until it died. So I assume turning off the gas makes it leaner. So maybe I should go smaller on the pilot or continue to back out the air screw some?

I get it home, heat it up to the same engine temp that it was in the parking lot (145) and ride up and down my street a couple of times and it idles great. It seems like it only happens after I do some engine breaking on down hills, then it is bad for a while. Outside of the leak down test, I have nothing else to try.
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Post by Mr. Wibbens »

I dunno sounds like its running normal to me
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Post by KarlP »

Sounds pretty normal to me, too.
A bit more tinkering may be in order but nothing drastic.

I don't think mine idles very well either. I've never really worried about.
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Post by lemmy »

Ok, I got to ride it after putting the stock reeds back on. At first heading up the mountain the thing was running great. Maybe better than ever. But it was about 40 degrees so I thought maybe it just made it leaner and so it was running good. Well, I get on up there and suddenly it starts dying on me again. Really bad. Then it would be really hard to start. One time I even replaced the plug and it took me 15-20 minutes to get it going again. Then at the end I was coming down and I put it in neutral and let it idle. It would start to die. Then I would immediatly ride up on the side (a bank) which would make the bike be pointed up hill. Then it would smooth out and and slowly increase to a very very high idle. Point downhill and it would die again. I got in the parking lot and messed with it and found that it didn't take much. Just a slight downhill and it would die, slight uphill and it was fine. I would think this points to float valve, but the float valve looks like brand new. Maybe it is the seat, but it looks great too. Any ideas?
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Post by TWMOODY »

As long as you can ride up the hill all is good cause you can always
coast down the other side right ? :lol:
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Post by lemmy »

Well, yeah its definitely better than the other way around. I swear it seems like a fuel level issue, but I have measured 4-5 times and it is right at 17mm. If I raise the float (lower the fuel level) more than 1mm then it will be beyond the maximum specification.
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Post by canyncarvr »

In an attempt to kind'a try to sort'a straighten this out, please note:
lemmy wrote:The "won't idle when warm" was a misdiagnosis of the problem. It has nothing to do with warm or cold.
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