KDX220 Starts Fine & Idles but Dies If Give It Gas

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BossHoss333
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KDX220 Starts Fine & Idles but Dies If Give It Gas

Post by BossHoss333 »

Well, I have had this KDX for about 2 months now. I really like bike and it has been awesome up until this point. I took a ride through the woods about two days ago. Bike ran just fine with no problems at all. Came home parked and shut off the petcock. Then Yesterday I was gonna run up to the store so I pulled her out and she kicked right up on the 2nd kick with choke on. I went to twist the throttle and the bike bogged down and died immediately. I figured maybe she just needed to warm up or something so I kicked it again. Started right up first kick. Let it sit there idling for a few minutes, hit the throttle & she bogged down and died again. Then I tried with the same result about 10 more times before I gave up. When I say she boggs down and dies that's what I mean. It's not like running out of gas more like when you stall out going too slow in gear or like it's getting flooded. It will idle just fine but just the slightest turn of the throttle and bogs down and shuts off. Anyway, I disconnected fuel line from carb and checked fuel. Got plenty of fuel there. Pulled the spark plug and it was black and wet. Put a brand new plug in. Then I pulled the carb and went through the carb. It's a brand new RB designs modded carb that I have only had about 2 weeks but I pulled the jets and cleaned them out anyway even though they looked fine and I didn't see anything blocking any of the jet holes. Put the carb back on and same problem. Then I tried my original carb that worked perfectly fine when I took it off 2 weeks ago and started the bike only to have the same problem. I also pulled the air filter off and cleaned it. Same thing. Tried with air filter off altogether. Same thing. I'm not really sure where to go from here. I was thinking maybe the kips valve. I didn't really feel like pulling the top end yet so for the time being I took off the pipe, and the side cover on the right hand side that allows access to the gear which turns the kips. I looked in the exhaust port while I turn the gear and I can see the valve moving about I guess a 1/8" or 1/4". Not sure how much it is supposed to move as this is the first time I have been in there so far. Don't look like I can get the cover off the kips valve without pulling the top end? I know I can't get a socket in there and wrench ain't working either. Anyway, that is where I am at for the moment. If anybody got ideas I really appreciate it?
BossHoss333
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Re: KDX220 Starts Fine & Idles but Dies If Give It Gas

Post by BossHoss333 »

Also forgot to mention I pulled the reed out also. I'm still fairly new to 2 strokes so I don't know exactly what I am looking for there but it looked perfectly fine to me. I didn't see any tears or anything. Looks fine from what I can tell.
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Re: KDX220 Starts Fine & Idles but Dies If Give It Gas

Post by bufftester »

I can tell you absolutely that it's NOT your KIPS valve. Sounds like a classic fuel issue. Idle jet is working fine but main isn't. Ensure that your slide is indeed opening when you twist the throttle. You say you get plenty of fuel at the carb, but how did you measure it? There is a filter on the petcock in the tank, make sure that is clean. The other candidate could be a stuck or hanging float in the carb. As for reeds they should lay flat against the cage with no cracks or tears in them.
BossHoss333
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Re: KDX220 Starts Fine & Idles but Dies If Give It Gas

Post by BossHoss333 »

I thought fuel issue at first also, I disconnected the fuel line to the carb, turned the petcock on and watched fuel come out like water from a garden hose. I know the filter in the petcock is clean also because I just replaced the tank a couple weeks ago and cleaned/installed petcock at the same time. I'm glad to hear it isn't the kips valve though. You just saved me from pulling my top end for nothing. I thought carb too but I don't see having the same problem with two carbs that were both functioning perfect up until today unless it's gas getting to the carb which I ruled out. I held both carbs in my hand with the slide installed and twisted the throttle "at different times of course". Everything working there. I'm gonna go through the carb again tomorrow anyway and pull the reeds out again. Double check gas coming from the tank also. At least I know what direction to go from here. Thanks. Really appreciate it.
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Re: KDX220 Starts Fine & Idles but Dies If Give It Gas

Post by 6 Riders »

Did you check to see if that stock piston was ever replaced? Do you have a pipe plug in the silencer? Does the bike start on the first kick, 2nd, 3rd or more?
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BossHoss333
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Re: KDX220 Starts Fine & Idles but Dies If Give It Gas

Post by BossHoss333 »

Previous Owner said he replaced top end with wiseco piston not to long before I bought it. I haven't pulled top end so I can't say for sure that he did but he didn't seem like the type to make stuff up. I did pull the head and take a look in there and everything looks good. I couldn't see the skirt of the piston but I could see the cylinder walls, and the head of course. That stuff looks fairly new. I do have a pipe plug on the silencer which I actually had not noticed until today. I opened it and a bit of oil drained out. Not a lot but a little bit. As far as the kicking goes it usually takes anywhere from 2 to 4 kicks. Usually about 2 if I have the choke on when it's cold. But, thats not really a fair judge on how many kicks it takes. The kicker has an issue where it slips unless you push it down about half way until you feel some back pressure and then kick it. As long as you do that it kicks just fine but if you try to kick it from the top it slips. So because of that sometimes take me a few kicks to get a good kick on it. I think it would start after a couple kicks every time if wasn't for that. As long as I can kick it and it starts for now I'm not worrying about the kicker. Previous owner been doing it that way for a couple months and I been doing it that way for a couple months now without any issues so as long as it's starting like that I'm gonna wait on it.
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Re: KDX220 Starts Fine & Idles but Dies If Give It Gas

Post by BossHoss333 »

Ok problem solved! You were correct on it being fuel issue. Wasn't type of fuel issue I was thinking but it was a fuel issue. I keep a couple 55 gallon drums on my property full of gas that I use for my dirt bikes and 4 wheelers. Guess I must have not tightened the lid on one of them tight enough and it has gotten water in the gasoline. I had just switched over to a new drum after emptying the other one. I noticed that when I turned the petcock on with the hose disconnected for about the 3rd time and let it drip onto the floor that the first few seconds it was clear instead of premix color. Then I looked at the garage floor and it looked exactly like water looks when it puddles up on oily concrete. I had my Kx sitting there with some gas from the previous drum in it. Used that gas on the KDX and it started up second kick. Ran real rough for a few minutes but after that it cleared up and runs fine now. No more bogging everything back to normal. Thanks for the help guys. I appreciate it. I was really close to pulling the top end and going through the kips if you wouldn't have told me otherwise!
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