KDX220 won't idle when warm

[lemmy]

Yeah, I think you are right, but I just can't figure out what to do about it. I guess I cold increase the float height to something like 20mm which is 2mm over the max and 3mm more than what it is now. I have the bowl off now and turn on the fuel and verified that when I push the float up, the fuel flow stops. I guess I could try to find an extra drain and drill a hole in and expoxy a nipple on it for a clear hose.

The only other thing I could think of is the fuel filter on my fuel line:

The filter is somewhat horizontal and I could see more fuel flowing while going uphill than going downhill. However I tested it in the garage (just raising the rear wheel about 10 inches) and the fuel flowed fine. Also, it seems to be too rich when going downhill, not too lean.

 

[lemmy]

I tried another method of measuring the float heigh. Using calipers accurate to 0.01mm I made a mark on the jet block exactly 18.00mm blow the base of where the float bowl o-ring contacts. Then I put the float on and put a long piece of fuel line on the fuel inlet of the carb and I was blowing through this line. I hold the carb upright and lower the float as I blow through the fuel line. As soon as air starts coming through I notice where the lowest point of the float is relative to the mark. It was about 1mm above it (I had measured at 17mm before so this is about right). So I bent the tab on the float and now it is about 19mm. This is beyond the maximum specification. But I really don't think that small of a change is going to make that much of a difference. I thought I had read that carbs are made where the fuel is supposed to begin to flow into the bowl when the mold line in the plastic floats is parallel to the edge of the carb body. If it was parallel it would be a float heigh of about 15mm.

 

[julien_d]

I have used like a rubber stopper for a beaker, and put a clear hose in the hole in the stopper and then stuff that stopper in the large drain hole in the bottom of the carb bowl. If the carb is actually flooding the engine when you're going downhill, then I would think the fuel level is too high. Does it sputter and die, or does it "lean out" like it would when you are running out of fuel? If you have raised the float level, you would be increasing the fuel level in the bowl. There's a fine line between enough and too much fuel in the bowl.

J.

 

[lemmy]

When I am measuring the float level the carb is upside down. So increasing the distance between the carb and the bottom of the float when fuel begins to flow is what I call increasing float height measurement. But it is actually lowering the float in normal operation with the carb upright. Currently at 19mm the float is 1mm lower than specification (which would make less fuel in the carb bowl).

That is a good idea with the rubber stopper and tube. Now if I can just find where to buy something like that locally. Thanks.

 

[lemmy]

I found a brewing place that may be able to fix me up with a stopper. Thanks for the idea.

The only reason I don't think my fuel level is too high though is that I rarely see my bike spew gas out the overflow, even when leaned over.

 

[julien_d]

I found a brewing place that may be able to fix me up with a stopper. Thanks for the idea.

The only reason I don't think my fuel level is too high though is that I rarely see my bike spew gas out the overflow, even when leaned over.

yeah. i saw that earlier in the thread. And you're sure the overflow is not stopped up or anything, right?

 

[lemmy]

yeah. i saw that earlier in the thread. And you're sure the overflow is not stopped up or anything, right?

Yeah, I just checked that about 10 minutes ago. I blew through the hose and no restrictions at all.

BTW, I got the stopper and hose. Do you know what the fuel level is supposed to be relative to the float bowl mating surface? I have heard 0mm to +2mm (but not -2mm) but I don't know if +2mm is above or below.

 

[sr5bidder]

my factory kdx manual says 0 to +2mm above matting surface ...it is the 95 kdx manual

 

[sr5bidder]

oh and that fuel filter you have there in the picture, well let me tell you I had one just like it on my 1973 xl175 and it caused me alot of trouble tuning the carb ALOT!! seems to airlock the fuel to some extent. I went to another stytle and it fixed me up.

Please try a straight section of tubing or a better filter like the flat round style that they sell for riding lawnmovers.

That would be great if thats all it was all along!!

 

[lemmy]

You mean one like this:

I was going to take that filter out, but I can't find any other good fuel line around here. The stuff I got at cycle gear was 1/4" on the inside like it is supposed to be, but much smaller on the outside than what I have. So the little clamp that tightens it up around the petcock wouldn't seal and it would drip.

 

[lemmy]

I checked the float level at it was right at the mating surface. If I tilted the carb forward about 45 degrees then tilted back to flat it was about 1mm above. Also, if I tilted forward 45 degrees then after 10-20 seconds it dripped a couple of drops of fuel out of the intake side of the carb, but not very much at all. So I put everything together with new fuel line (no filter). I warmed it up to 150 degrees, took it up on a small hill in my backyard and as soon as I pointed it slightly down it would start to die. I tried it again with the fuel turned off and it wouldn't die. So I assume this is definitely a fuel level issue. So I am going to set the float height to about 23mm and then go up in pilot and main jet a bit so that hopefully it won't get too lean. It may seize on me, but at this point I really don't care. This bike is unrideable and I couldn't sell something like this to someone and feel good about myself.

 

[lemmy]

I adjusted it to 21.5mm. Then I checked the fuel level with the clear hose and stopper and it was at least 2mm below the mating surface. It was better. I could point the bike slightly downhill and it wouldn't die. However there is a short ~6 foot section of moderately steep downhill in my yard (I checked, its a 10-15 degree hill). I rode up to the top and pulled in the clutch and coasted down the hill. By the time I got to the bottom of the hill it was about to die. Since turning off the fuel helps, I think it is definitely a fuel level problem. However I don't think I can go much lower with the floats. I am already 3.5mm beyond the limit and I think the floats will be hitting the bottom of the float bowl soon. Is there anything else for me to try, or should I just try to sell this bike as a parts bike? Is there anything inside the engine that could be causing this?

 

[sr5bidder]

You mean one like this:

I was going to take that filter out, but I can't find any other good fuel line around here. The stuff I got at cycle gear was 1/4" on the inside like it is supposed to be, but much smaller on the outside than what I have. So the little clamp that tightens it up around the petcock wouldn't seal and it would drip.

yep like that one I know it sounds wierd but the filter you have on now coused me ALOT of problems in tuning

 

[lemmy]

yep like that one I know it sounds wierd but the filter you have on now coused me ALOT of problems in tuning

I believe it. I kind of noticed that vapor lock thing you were talking about. But unfortunately that filter was not the problem.

 

[sr5bidder]

does anyone you know have a carb you can borrow maybee cracked somehow internally.
did you say you rode at barber motosports if so where do you live? I have a minuki you are welcome to try.


Also have you removed the cylinder? I have heard alot of 220 owners speak of inspecting a running bikes piston and finding a crack all the way down the skirt on the intake side and it still was running.

Many replace the stock piston with weisco for this reason!

 

[lemmy]

I have not removed the cylinder. I have looked in the intake and exahust side and not noticed anything like a crack. I have no idea if this bike has a stock piston or the weisco.

I live in Knoxville TN which is about 4 hours away. I just met a guy that got rid of his KDX just one week ago. But everyone I know has a 4 stroke. Will just about any 2 stroke carb work? I don't mind buying a new carb if I really thought it would fix it, but I am not convinced it will.

 

[sr5bidder]

have to think the only thing that changes going down hill is the trans oil gets moved forward towards the crank case and of course the fuel in the bowl.

next time you get it running
In neutral lean it over to the left and hold it then right ..I'm talk'n till the handle bar is on the ground. I walked off the front of mine sunday and it ran fine laying over to the right long enough for me to put my shoe back on and scould my bike for taking it off!

As far as the carb from any bike not really two stoke carbs a a liitlle bigger to cc ratio than 4tokes

 

[sr5bidder]

does this happen when coastin g clutch in down hill or just engine braking

 

[lemmy]

My experiments recently were with clutch in coasting down the hill. This was when it would almost die and then turn it uphill and it would suddenly idle very high. However with clutch out and engine braking it will generally keep turning over, but it has died on me and locked up the rear. Also, if I am engine braking then pull in the clutch to blip the throttle (to get some lube in the engine) it will die if I am not really quick on the throttle. So to answer your question...it dies in both conditions.

 

[lemmy]

have to think the only thing that changes going down hill is the trans oil gets moved forward towards the crank case and of course the fuel in the bowl.

next time you get it running
In neutral lean it over to the left and hold it then right ..I'm talk'n till the handle bar is on the ground. I walked off the front of mine sunday and it ran fine laying over to the right long enough for me to put my shoe back on and scould my bike for taking it off!

As far as the carb from any bike not really two stoke carbs a a liitlle bigger to cc ratio than 4tokes

I just went out and tried it. When I leaned past about 55 degrees it started sputtering and acting like it was going to die. By the time it was fully over it was dieing so I gave just a bit of throttle and it cleared up and then with no throttle it slowly started idling higher than it had sitting upright. Same thing left and right. I am thinking that it was loading up (just like when it goes downhill) but then I gave it some gas and by then much of the fuel had gone out the overflow and so it started running lean (just a guess).

 

[sr5bidder]

well I live about 2 hrs from barber motorsports park so thats prob 2hrs from knoxville
you are more than welcome to bring your bike here and try my carb on saturday or sunday the only other thing i can do for you is get one of my minuki kdx carbs working on my 98kdx200 to make shure it works well and stick it on ebay for you private auction?? ship it to you, if it works ..you know if not send it back and I can refund you

I'm not trying to sell anything really just not giving away parts is all.

the 86 kdx uses the same reed valve assem and the same piston as the 98 so in theory the minuki will work.

Hell I think I'll try it this weekend on mine seeings how its going to be like freezing outside!!

 

[lemmy]

I may end up taking you up on your offer. If you do try it, let me know how it goes. Thanks!

 

[julien_d]

I was gonna try tuning the carb on mine a bit today, but I woke up to about 5 inches of snow :|. bummer....

J.

 

[sr5bidder]

5" thats great I'd love to ride in snow haven't done it since I was 12 on my minitrail 50

plus the cold air makes for more hp

 

[julien_d]

5" thats great I'd love to ride in snow haven't done it since I was 12 on my minitrail 50

plus the cold air makes for more hp

Well, I might be doing that today :). Awful cold out there though. about 19 and windy right now.