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Dies when warm, especially slow down hills

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99 kx250, runs good on everything but idle. When warm it constantly tries to die on steep down hills. Starts great when cold. Got some form of a rich condition but don't see why.

Riding is sea level to 2000ft.

pj:40

needle is stock, clip in 3rd(or 2nd from top, can't remember)

main:158(tad rich but I'm trying not to change multiple circuits at once, have a 155)

float height is the stock 7.5mm, new inlet needle had no change in running 

gnarly pipe, turbine core 2 silencer, clean no toil filter.

air screw does nothing. Floats have no leaks(both shake test and submerge tested). 

I thought the inlet needle would have fixed it, turns out it's a bitch to find 99 carb parts. Fuel inlet Needle is 35$(!!) for oem Kawasaki. I saw on a website the inlet valve needle was same part number as later year pwk's so I grabbed a kit for a later year(2000 inlet needle and rebuild kit for 22$). The inlet needle looked the exact same with maybe the little spring bumper inside a little shorter. Readjusted float level to compensate, problem still exists.

any suggestions? Anyone run a slightly lower than stock float height? The jetting should be lean on the low end according to my homework, but it seems pretty rich

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fwiw all pwk float needles are the same 36/38 mm

did you polish the seat where the needle goes into ?

does it leak out the over flow when bike is at less then a 45 degree angle ? ( almost upright )

when you set the float height was the float needle compressed ? 

also the standard needle is still rich at clip 2 at sea level and would be even more so at 2000 ft

search spanky's jetting guide and start from the bottom (pilot jet and air screw setting)

if the air screw does nothing your idle might be to high and it is bypassing the pilot circuit and is running on the rich needle

 

Edited by kxrob
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@kxrob

Thanks for confirming it's the same needle:thumbsup:

i had a wooden pencil with the lead removed, and used it to polish the seat, is that good enough? Il try your method if different.

i don't know, should I hoist the rear and check? Or just tip the carb?

the little bumper spring wasn't compressed I try to hold the carb at a 45 to eliminate that

i have a 38 pilot jet in my tool box, any needle recommendations? Maybe 1st clip position to try out?

i don't know the rpm but the idle sounds about right,  ting ting ting, instead of a smooth sport bike-ish sounding idle

Edited by RawbW

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1 hour ago, RawbW said:

@kxrob

Thanks for confirming it's the same needle:thumbsup:

i had a wooden pencil with the lead removed, and used it to polish the seat, is that good enough? Il try your method if different.

i don't know, should I hoist the rear and check? Or just tip the carb?

the little bumper spring wasn't compressed I try to hold the carb at a 45 to eliminate that

i have a 38 pilot jet in my tool box, any needle recommendations? Maybe 1st clip position to try out?

i don't know the rpm but the idle sounds about right,  ting ting ting, instead of a smooth sport bike-ish sounding idle

only ned to tip bike side to side to verify if over flowing no need to lift the rear 

i polish the seat with a cue tip and a small drop of car polish

i recommend the suzuki rm250 needles but before i give you a part number i need to know your temps where you ride summer and winter 

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@kxrob

Thanks for the tips:ride:

I've heard of using Suzuki needles before but didn't know numbers

summer temps are about 80-100 degrees

winter is 50-70 usually

elevation typically say 500ft - 2500. 2800 is the highest point of usual riding.

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ok ,

42-45 pilot

needles :

summer 65f plus NEDJ clip 2 ( may get away with this needle in winter , i have run it in 60 degree weather at sea level )

Winter Below 65 NECW Clip 3

leave main at 158 

google search the nedj and necw the part numbers pop straight up

 

 

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@kxrob

Thanks a bunch! That was some needle info I needed.

my winters are not very cold, no weather extremes beside summer heat where I ride in ca

now if I could pick up a whole rm250 for my stable too

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