Adjusting the mixture on a carb.... Needle valve?

[dgk13]

I've got a 2004 TZR50, which is running to lean due to a resent addition of a K&N... i need to adjust the mixture to make it more rich...

Yes i know i need to adjust the needle valve... one problem... where is the needle valve on the carb generally?

I mean i've got 2 stroke models and the needle valve is near the fuel line entrance, but there are a few screws and knobs on my carb, not sure which one it is.

Hope someone can help me, thanks.

Dan
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Honda powwwwerrrr

[stinkwheel]

Get someone else to do it or read up on carburettors some more.

The needle valve controls how much fuel runs in to the float bowl of the carb. Don't mess about with it.

The throttle needle controls at what throttle position the main jet is fully open (this can be adjusted up and down by moving a circlip). The taper on the throttle needle controls the amount of fuel delivered at middle throttle openings.

The diameter of the main jet controls how much fuel is delivered to the engine at full throttle.

If you have fitted a more free flowing air filter, you will probably need to deliver more fuel at wide throttle openings, so you would need to fit a bigger main jet (but not always, they are funny things 2-strokes).

You might also need to fit a new throttle needle with a different taper on it to supply more fuel at 1/2 to 3/4 throttle (but not always).

You might need to alter the fuel:air mixture at tickover using the mixture adjustment screw.

You can roughly set them up by doing flat-out runs, stopping and checking the colour of the plug electrode. If it is running lean, fit bigger main jets. If it is running rich, fit smaller main jets. This is time consuming and not very accurate.

Best bet would be to leave it to an expert.
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