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Bought a 99 KDX 220 in the fall. I have to continuously crack the throttle to keep it running. It will idle for a few seconds, but will die out. It runs fine when I am on the throttle. The idle adjustment screw is all the way in. The air screw doesn't seem to affect the idle speed. I have noticed that when the bike is about to run out of gas, the idle speed seems to increase before dying. Runs rich throwing spooge out the silencer.

Stock Carb
Stock Jets
Boyeson 607 reeds
About 30 hours on top end
FMF desert pipe, stock silencer, no airbox mod yet

Can you guys think of anything to help me?

Are you sure the pilot jet is clear? Has the bike been sitting unused for a while? Sounds like maybe the pilot jet, or some of the small passageways in the carb, are clogged.

Jim B wrote:Are you sure the pilot jet is clear? Has the bike been sitting unused for a while? Sounds like maybe the pilot jet, or some of the small passageways in the carb, are clogged.

I put a brand new 45 pilot jet in today, but it didn't change. I ride it almost every weekend. I may try taking the carb off again and see if I missed something while cleaning. Would the needle or float cause this problem?

Thanks.

Running out of gas creates a lean condition so your RPMs will rise. That's normal. If you haven't cleaned the crab (remove jests and really clean) then you are just guessing. With a clean carb, fresh gas, good flow from fuel valve, correct float height, clean filter and new plug you should't have any issues. If you do, then let's hear what they are and go from there.


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claybo wrote:I may try taking the carb off again and see if I missed something while cleaning. Would the needle or float cause this problem?

I'd make sure the body of the carb is clean. Like I said previously, make sure all the small passageways/orifices are clear. Try (carefully) spraying carb cleaner up through where the pilot jet goes, after removing the pilot jet. There are a few more places; make sure you have a good look at the carb body and clean everything you see. Use eye protection and gloves.

The needle or float could cause the problem. Do you have the float height set correctly?

It sure sounds like a carb problem, as it runs okay at larger throttle openings.

I'd say it's to rich. Spooge, no response to air screw,sounds rich to me. Replace jet block gasket and follow jetting guide.

Okay I have ordered a new jet block gasket. I'll also deep clean the carb and attempt to set the float height and see if this changes anything. Thanks for everyone's help.

claybo wrote:Bought a 99 KDX 220 in the fall. I have to continuously crack the throttle to keep it running. It will idle for a few seconds, but will die out. It runs fine when I am on the throttle. The idle adjustment screw is all the way in. The air screw doesn't seem to affect the idle speed. I have noticed that when the bike is about to run out of gas, the idle speed seems to increase before dying. Runs rich throwing spooge out the silencer.

Stock Carb
Stock Jets
Boyeson 607 reeds
About 30 hours on top end
FMF desert pipe, stock silencer, no airbox mod yet

Can you guys think of anything to help me?

after chasing my tail for a year with my old worn out carb, i ordered a new pwk35.

i don't konw wether it was the slide or needle seat, or a combination of both, but the old carb was not metering fuel as it should. the new carb is nearly perfect.

while you have your carb apart, clean all the passages very carefully, and use the jetting guide to try and dial-in your jetting, one step at a time.

I got the new jet block gasket put in today. It really woke the bike up. I don't think it has ever been in good shape, because I've never seen the bike run like it does now. However, the idle adjustment screw doesn't seem to change much. The bike idles high when it is cold, but when it gets hot, it only idles with the screw all the way in. Does this sound right? With a 40 pilot in (the smallest I have), I got a slightly faster idle at about 2.5 turns. Do I need a smaller pilot jet?

I'd throw a 42 in and see if your idle continues to raise as you adjust the air screw.