Ninja 250 Carburetor Needle Information: Difference between revisions

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The needle is tapered, so that as it's pulled further out of the main

jet, it blocks less of the port, and more fuel is allowed to flow.

The needle in a carburetor is the main method of adjusting the mixture at partial throttle openings. It blocks some of the passageway to the main jet (the main jet size determines the carb's overall mixture), reducing the amount of fuel allowed to flow at part throttle. This keeps the mixture consistent through a range of throttle openings: as the throttle opens, raising the slide, the needle also raises (it's attached to the slide). The needle has a tapered profile, so that as it pulls out of the main jet port, it blocks less and less of the port, allowing more fuel to flow, ideally matching the amount of air flowing through the carburetor. By the time the carburetor is at full/wide-open throttle, the needle is completely clear of the main jet port, allowing it to flow without restriction.

The rate and positions at which the needle tapers, along with the

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the engine, correspondingly more fuel is drawn in as well.

~~Needles~~ only really ~~have~~ one adjustment: height. As you raise a needle

A given needle only really has one adjustment: height. As you raise a needle

(by moving the clip lower on the needle, or adding washers), you enrich

the mixture. As you lower a needle, you lean the mixture out, all at

partial throttle.

~~Another adjustment you~~ can ~~make with~~ needles ~~is to replace them with a~~

You can also "adjust" the needle by substituting other needles for the stock units, which have different taper profiles. There are two ways to

~~different needle~~, which ~~has a~~ different ~~profile~~. There are two ways to

do this: you can purchase a jet kit, or you can try needles from other carburetors. Enterprising riders with machining skills may also manufacture their own needles on a lathe, but this is beyond the scope of this article.

do this ~~with pre-made needles~~: you can purchase a jet kit, or you can

try needles from other carburetors.

The Factory Pro and DynoJet jet kits provide clip-adjustable needles,

The Factory Pro and DynoJet "jet kits" provide clip-adjustable needles,

and are misnamed: they're really a set of custom-made needles, with

and are misnamed: they're really a set of custom-made needles (into which FP or DJ has put a lot of work and research), with

some jets thrown in very nearly as an afterthought. They should be

called needle kits.

@@ Line 9: / Line 9: @@
 The needle is tapered, so that as it's pulled further out of the main
 jet, it blocks less of the port, and more fuel is allowed to flow.
+The needle in a carburetor is the main method of adjusting the mixture at partial throttle openings.  It blocks some of the passageway to the main jet (the main jet size determines the carb's overall mixture), reducing the amount of fuel allowed to flow at part throttle.  This keeps the mixture consistent through a range of throttle openings: as the throttle opens, raising the slide, the needle also raises (it's attached to the slide).  The needle has a tapered profile, so that as it pulls out of the main jet port, it blocks less and less of the port, allowing more fuel to flow, ideally matching the amount of air flowing through the carburetor.  By the time the carburetor is at full/wide-open throttle, the needle is completely clear of the main jet port, allowing it to flow without restriction.
 The rate and positions at which the needle tapers, along with the
@@ Line 16: / Line 18: @@
 the engine, correspondingly more fuel is drawn in as well.
-Needles only really have one adjustment: height.  As you raise a needle
+A given needle only really has one adjustment: height.  As you raise a needle
 (by moving the clip lower on the needle, or adding washers), you enrich
 the mixture.  As you lower a needle, you lean the mixture out, all at
 partial throttle.
-Another adjustment you can make with needles is to replace them with a
+You can also "adjust" the needle by substituting other needles for the stock units, which have different taper profiles.  There are two ways to
-different needle, which has a different profile.  There are two ways to
+do this: you can purchase a jet kit, or you can try needles from other carburetors.  Enterprising riders with machining skills may also manufacture their own needles on a lathe, but this is beyond the scope of this article.
-do this with pre-made needles: you can purchase a jet kit, or you can
-try needles from other carburetors.
-The Factory Pro and DynoJet jet kits provide clip-adjustable needles,
+The Factory Pro and DynoJet "jet kits" provide clip-adjustable needles,
-and are misnamed: they're really a set of custom-made needles, with
+and are misnamed: they're really a set of custom-made needles (into which FP or DJ has put a lot of work and research), with
 some jets thrown in very nearly as an afterthought.  They should be
 called needle kits.