float height 23mm?

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kdxdazz
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float height 23mm?

Post by kdxdazz »

still trying to get my awful running kdx220 running right. when i bought it the float height was set at 19mm, it ran terrible,would barely idle,had black smoke pouring out of it,tons of spooge and used so much fuel. after trying every possible combination,including setting the float height to 16mm in which case it barely ran i set the float height at 23mm with a 35mm pilot jet,air screw at 2.5 turns out and it runs the best it ever has although it is still too rich. i'm going to try raise the float height to 24mm tomorrow and see what happens. strangely enough at 19mm it would ping very badly at half throttle and at 23mm float height that has stopped. at its current settings it still will not idle well although before the idle screw was turned all the way in.
any thoughts on why this float height is so high, the carb is 36mm with rb mod done but pretty sure its a chinese copy
1999 KDX220SR (KDX220-B5)
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doakley
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Re: float height 23mm?

Post by doakley »

I'd suggest trying to find someone with a stock carb to swap for a test run. That will at least tell you if it's the carb or something else.
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Re: float height 23mm?

Post by KDXGarage »

Is there a coffee stamped into the side of the carb by the float bowl?

What else have you checked and not checked?
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Re: float height 23mm?

Post by bufftester »

+1 on what doakley said. A stock pwk33 will tell you a lot. Is the rest of the bike mechanically sound? Reeds, boots, compression, etc. A 36 is a big step up in carb size for the 220, you will sacrifice some bottom end. But if it is a chines clone it may never run right, hence looking for a stock carb to borrow makes good sense.
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Re: float height 23mm?

Post by kdxdazz »

i thought the 36mm carb with rb mod was the done thing,i changed the the jet block o ring a few days ago and that was about a 5 percent improvement. borrowing anything is not possible here in thailand. the previous owner said the motor was rebuilt not long ago but i haven't done any leak down checks. is it possible the float is in upside down? i have the flat edge of the float facing upwards to inside the carb body and the curved side facing the float bowl. when i get back to australia i will try source a genuine pwk33 as most of the riding i do is single track. tuning this bike has proved to be impossible both by the previous owner and me but now i know the float height is the issue it might start to get easier. i have a bung welded in the exhaust so i can put in my wideband sensor but reluctant to do so until i can get it running half decent.
the carb right now has a non genuine 35 pilot jet but will try source a genuine pilot jet today just so i can rule that out
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Re: float height 23mm?

Post by bufftester »

I don't think you can get the float in upside down and close up the carb, at least I have never tried. Regardless, float height alone is not your problem, you don't get black smoke and pinging from a misadjusted float. I would suggest setting it to 18 and then go through the jetting guide. All that is based on the motor and exhaust/intake tracts being serviceable of course.
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Re: float height 23mm?

Post by kdxdazz »

today i sourced a genuine 35 pilot jet and raised the float level to 23.8mm. ran well but still winding the air screw all the way out had no effect. i had the JD blue needle clip 4 in, i tried the JD red needle clip 4 and for the first time it would stall when the air screw is turned all the way out,the bike rain smooth but very little throttle response,for the first time the smoke output was an acceptable level. i put the blue needle back in and left it at that until i come up with fresh ideas. i think i know what is going on with the float but difficult to explain with out photos,the tang looks like it is very out of shape compared to a new float. at 16mm fuel would just gush out of the overflow with the slightest of lean angle,18mm would see fuel gush out of the over flow at a 45 degree angle. tomorrow i will use the clear tube method and try and determine where the fuel height is
1999 KDX220SR (KDX220-B5)
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Re: float height 23mm?

Post by kdxdazz »

just an update. checked the float level using the clear tube method. float height set at 23.8mm gave a fuel height 5mm below the mating surface. 20mm float height gave a fuel level flush with the mating surface. after a bit of research the consensus seems to be that the number 5 slide that i have is too rich for the 36mm carb with rb mod and a number 6 slide should be used. can anybody shed some light on how these slide are measured and is a possible for me to modify the slide i have now so that its the same as a number 6
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Re: float height 23mm?

Post by bufftester »

Hate to say it again, but your problem is not just float height, or even throttle valve cutaway size. Until you get the right pilot jet in no amount of tuning is going to make it run right. Run through the jetting guide, changing only 1 thing at a time, don't skip around, don't change the order. If nothing you do makes any difference you may have a bad carb (high chance with the chinese clones). As far as slide cutouts go, slides are numbered based on the cut portion on the back side. A 5.5 has a .315 taper where a #6 is .365. I know guys have taken the grinder wheel to them to change it but there's not a lot of room for error and you can make things worse in hurry.
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Re: float height 23mm?

Post by John_S »

I had a pwk 36 that was puking rich near idle that I spent way too much time trying to jet and changing the float heights. I bought a brand new pwk 38 and decided to put the slide in the 36 to test (same number slide) and from the second it kicked over I knew it was fixed. If the bore that your slide runs up and down in is out of spec or the slide is out of spec you could be chasing your tail. Being a clone carb I wouldn't trust that the tolerances are the same as a genuine. Look at what a big difference practically microscopic changes to jet hole sizes or needle tapers/diameters make on the way a bike runs. Even jetting a brand new carb can test your patience. Time is money as they say and you've put a lot of time into that carb. I would take the hit and go with a new genuine carb.

Edit: Did you check or change the reeds?
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Re: float height 23mm?

Post by kdxdazz »

i think you guys are right. will source a carb when i get back to australia, only checked the reeds by putting my hand over the inlet boot to check for no blow back,when i get time i will pull the reeds out and check them but from what i read hard starting is more a cause of bad reeds than rich at idle and my bike starts second kick
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Re: float height 23mm?

Post by 6 Riders »

Have you checked the petcock?


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Re: float height 23mm?

Post by kdxdazz »

6 Riders wrote:Have you checked the petcock?
checked the petcock for what? i know when i turn it on fuel comes out

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Re: float height 23mm?

Post by 6 Riders »

kdxdazz wrote:
6 Riders wrote:Have you checked the petcock?
checked the petcock for what? i know when i turn it on fuel comes out

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Does fuel come out when the petcock is off?

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kdxdazz
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Re: float height 23mm?

Post by kdxdazz »

no fuel comes out when petcock is off
1999 KDX220SR (KDX220-B5)
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