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Author Topic: 03 kx125 carb issues.  (Read 2067 times)

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Offline Sapper

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03 kx125 carb issues.
« on: December 16, 2012, 01:14:25 PM »
Having major issues with this carb. Setting the float height has me pulling hair, tossing dammit-wrenches etc, etc.

Following the manual, I set it at 9.5mm. No fuel comes out. Set it at 9mm, it leans out by yhe 3rd hit of the throttle. Set it at 8.5 runs pretty good but then fuel runs out after bike is shut off.

The I did some research and found on jets-r-us site that TMX38 (late model) the float height is 6-7mm.  Huh, well I'll let you guess how much fuel cam rushing out.  :o

Anyone have any ideas??
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
If you want cheap & fast, it won't be good.
If you want cheap & good, it won't be fast.
If you want good & fast, it won't be CHEAP

Offline SachsGS

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03 kx125 carb issues.
« Reply #1 on: December 16, 2012, 02:55:56 PM »
Advertized float heights are really only guide lines meant to get you in the "ball park". If you think about it, if the float height is too high the floats will contact the underside of the carb unseating the check valve needle and flooding the engine with gas. If the float height is too low at full throttle the engine will draw the fuel level down to a point where the pilot jet is exposed and air is drawn in, leaning the engine.

With the float bowl removed, set the float level at point where the floats are horizontal (typically) when the float assy. just begins to contact the spring loaded pin on the check valve needle (make sure it isn't stuck or worn). At this point you can begin to fine tune jetting. ;D
« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline Sapper

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03 kx125 carb issues.
« Reply #2 on: December 30, 2012, 01:37:58 PM »
I think I got it 95% fixed.
Turns out the tab on the float that rides in the needle seat had a small wear dimple in it and was causing the pin on the needle seat to stick and not properly slide on it. So I cleaned it up and polished it with a dremel tool.

Don't ask me why or how but for some reason, the choke stated working properly too. (staying up) It NEVER stayed up on it's own. Now it clicks and stays up.

I made my own float height guage from some thin cardboard from a breakfast bar box and a dial caliper. I set the floats at 9.3mm. So far it doesn't over-flow & doesn't lean out. But with it being cold and snowy, I tried to ride it around and the cold oil in the trans was causing the clutch to slip real bad. So I'll wait until a nicer day or wait until we hit the indoor track and let the boy flog it and do some tuning then.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
If you want cheap & fast, it won't be good.
If you want cheap & good, it won't be fast.
If you want good & fast, it won't be CHEAP