KDX220 won't idle when warm

[sr5bidder]

Lemmy
Maybe the spreadsheet is not as reliable as you thought
I would start back at stock like i think you may have already or at least with something proven.
I am no expert on the kdx, I have been working on motorcycles and 2 tokes for 14 years, and just thinking out loud

 

[G. Gearloose]

Not to be argumentative but its my opinion JD's worksheet is the bomb. Lemmy's bike just has something out of order. I concur trying to correct it with jetting well outside the norm is not productive.

 

[lemmy]

Well I mentioned that I went back to 42 pilot, 1173L needle and 152 main and the smoke was much less. The next day I started up, and again low smoke. I then started it the next day and it smoked like crazy. Same fuel, same everything. I am about to give up on this bike. I am going to actually go ride this weekend and see how things go. And then I may try doing a leakdown test if I can round up the parts to build a tester.

 

[Eric B]

My 220 had a leaky petcock(It leaked in the off position). Made the bike run rich for the 1st 10 minutes. You might want to check that..... and the needle valve. Replacing the 2 rubber pieces(in the petcock) fixed the leak.

 

[lemmy]

The needle valve looked fine when I took it out. I really don't know how to test if it is working or not. But something like that would make sense. The petcock doesn't leak though. I have had the tank off for hours or days and it hasn't leaked a drop. But I admit it doesn't sound something like that is going on.

 

[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.

 

[G. Gearloose]

Perhaps Try dropping the float level some more.

Wish you could take a rip on a good running machine so you could see what your aiming for,

 

[sr5bidder]

my factory manual says turn the air screw all the in and then out 1.5 turns from there it should make noticable changes in the engine to turn the air screw within a half turn either way

if it does not seem to make alot of difference to adjust the air screw go up on the size of the idle jet
and be sure there is only a small gap under the slide (meaning make shure your throttle stop is not all the way in)

gearloose has a point to, if your fuel level gets high enough it could cause havoc

man I'm really hate'n this for you lemmy

 

[lemmy]

The air screw adjustment does make a big difference. If I screw in 1/2 - 3/4 turn from where it is, it dies instantly.

I know the range for the float height is something like 15-18mm, and I think mine is right at the limit of 18mm. But doesn't higher float level measurement equate to lower float level during normal operation? Maybe I will try the 15mm end of operation and see how that works.

Thanks. I really appreciate the ideas. I have also replaced the RAD valve with the stock reed cage and reeds just as an experiment.

 

[sr5bidder]

good idea

tell me though, did you buy this bike with these problems, or did you have it for a while and then change some things (carb) to come to the piont your at with the runability problems.

 

[lemmy]

I bought the bike on July 12th. The same day I was injured in a track day at Barber Motorsports on my R6. So I didn't get to ride it for a long time. I rode it one time nad thought it had no low end power. I am pretty sure it had the idle problem them. I did some jetting but later found out the lack of low end power was due to the kips valve being open all of the time due to the claw being put on the wrong way. The kips works now and then I really started noticing the idle problem more. Then I went back to the jetting it had when I got it except for much leaner main (165 to 152) and a little leaner pilot (45 to a 42 and then a 40) and the stock 1173L needle with the clip in the 2nd position. Also, I noticed that the guy had no slack in the throttle. So much so that the accelerator was held up slightly. So I think it was having this problem when I bought it and that was why he had it adjust that way.

 

[sr5bidder]

Lemmy

just looked over everything, the whole post, again

And I dont see where you dunked the carb (cleaned) and used air to blow out all the circuits. I see where you said you might but not that you did

Also does the idle and air screw have the proper o-rings on it

 

[lemmy]

I did dip the carb in Berryman's for about 3 hours. Then blew everything out with compressed air. The idle screw is a plastic screw with a spring and I don't see where any o-rings would go, but there aren't any. The air screw doesn't either. I don't even know where they would go. There is a spring on the air screw too. Is it possible the seat for the air screw is messed up? That would take a new carb wouldn't it?

 

[sr5bidder]

does air or carb cleaner flow through the hole on th left rear face of the carb where it picks up air for the idle circuit when appart it should flow out the air screw hole then plugg with your thumb then it should blow out the idle jet hole plug with your idex finger then it should flow out a tiny hole in front of the slide (intake side)

the RB website says they clean up the idle circuit with thier 165 buck carb mod but i dont know if they would mess with the seat..

Did you try the stock reeds? I didn't see a ride report or notice rather if that was tried

 

[lemmy]

Ok, should I remove the pilot jet and air screw or leave them in? The hole where I should blow the air should be where the red arrow is right?

And it should come out where the air screw is screwed in, or where the black arrow is?


I have put the stock reed cage and reeds back in, but I haven't got to ride it. It has been raining every day since then. Even if I start it and ride it around the neighborhood and it runs ok, I won't know for sure until I get to go on a real ride. I have to be able to ride this weekend.

 

[lemmy]

Perhaps Try dropping the float level some more.

Wish you could take a rip on a good running machine so you could see what your aiming for,

I may have this backwards, but if I take the float level from 18 to 15, wouldn't that make the float sit higher and more fuel would be in the bowl, so it would run richer? I just want to make sure of the effect of what I am doing.

 

[sr5bidder]

if you got the bowl off and measure from the matting surface to the bottom of the bowl JUST as as the lever starts to touch the neddle valve that is the bowl hieght adjustment ..if you change that to 15 the level will be allowed to get higher in the bowl.

the way the factory manual says to do it is take the carb off empty the bowl attach a clear hose to the bottom of the carb ..clamp it level then attach a test bottle (mine is a 16oz aluminum bud light bottle w/ 1/4 inch nipple epoxied into the bottom, use test leads to hang on bars) hold the clear tube along side of the carb and open the supply valve to the bottle, then as gas fills the carb you will see the level on the tube and it should stop filling at 0mm or a maximum 2mm above the matting suface of the float bowl.
If not then adjust to make right

 

[sr5bidder]

Ok, should I remove the pilot jet and air screw or leave them in? The hole where I should blow the air should be where the red arrow is right?

.

yes that is the hole and take everthing out and apart blow air in all directions ,
in the sot you took the pilot out,
in the back side with finger over pilot hole and screw hole
in the screw hole with finger on back of carb hole , then again with finger on pilot hole
also make sure the air is coming out that tiny hole straight up through the pilot opening in th veturie of the carb body on the intake side of the slide

 

[lemmy]

I am confused. I thought the attachment on the bottom of the carb was for the overflow. So you are saying you are putting fuel from your test bottle, in to the fuel inlet (where the line from the gas tank normally connects) and then using the clear tube to see how high the actual fuel in the bowl is? It would make sense to me if the bottom attachment where you are hooking the line was drained from the bottom of the bowl instead of the over flow tube which is much higher than the fuel level inside the carb.

 

[sr5bidder]

yes clear hose =bottom carb says to remove the drain plug and use specail tool and the specail tool looks like the drain plug but with a nipple on it for the hose

sorry maybe the only way to do it this way is with the specail tool

 

[lemmy]

I took the carb apart tonight and blew through all of the holes. When blowing through the pilot jet hole, air come up through the tiny hole near the needle, and the tiny hole that is closer to the intake in the main body of the carb. I alse shined light up that hole and coule see light in both holes. Also air from the air screw hole would come out the pilot jet hole. The only thing is the air through the hole indicated by the red arrow in my picture seemed to come out through the choke circuit. Air through the hole on the bottom (indicated by the black arrow) was the one that had air coming out the air screw hole and the pilot jet hole. I think this is right.

I think the carb is as good as I can get it. It must be something else. I am thinking (hoping) that it is associated with that RAD valve. After all, it always seems to be a problem after doing some engine braking. I really don't know what kind of problem that would cause though.

 

[sr5bidder]

it would cause a high vacuum in the reed section of the intake and if the reeds aren't good then???
I may be wrong but aren't those rad valves adjustable tension? though I read somewhere that they where

Its raining here to ..if it don't stop soon it'll ruin my riding plans to

 

[lemmy]

so if it is a high vacuum, could it pull some fuel in the intake and cause it to be too rich? If they are adjustable, I don't see how to adjust them. I am planning on a ride tuesday, so I am hoping to try the stock reeds/cage then.

 

[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?

 

[julien_d]

It has to be the fuel level. Not necessarily the float valve itself though. I would re-check the fuel level again. Pull the drain off and find some way to stuff a hose in there and get it sealed off. I know you went through this already, but it can't be right if the angle of the bike is affecting it like that.

If I had to guess, the fuel level is too high and when the bike is pointed downhill it's loading up. When you get it pointed up the fuel level is ok IE fuel is no longer running through the carb into the intake boot. This would explain it taking you 15 minutes to get it cranked back up, the cylinder was full of fuel, most likely down in the crankcase as well.

There's my 2 cents