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Typical Needle Damage Areas
(and what causes it)
Alan Eccles sent in this scan of "Mink's" 64,000 km
old, stock non-US model TRX 850 needle - Ouch! :-)
(That's about 35,000 miles for the miles parts of the world)
Got another winner? Throw in in a scanner,
send a pic and we may put it on this page -
Send bike, mileage and your name -
Descriptions and Causes
|Spinning E-clips (also
known as C clips):
When installing E clips, make sure that they are a snug fit in the needle groove. If the clip rotates freely in the groove, it will "erode" the base groove and will eventually saw the needle into two pieces or the clip will actually fail. Replace distorted clips if available or, if absolutely necessary, gently pinch the clip to decrease its diameter. Replace the clip as soon as possible.
|Slide Hole Area:
If the needle rotates when it is installed, it will wear into a "funnel" shaped cross section. If it is prevented from rotating when installed, it will wear as shown in the diagram. Eventually, in either case, the needle will mechanically fail, but this wear, unless the needle physically breaks, usually doesn't cause a huge change in richness.
This needle is from a Legend Series fj1200 and is excessively worn, very fragile and should be replaced now.
If the diameter is only .002"-.005" worn at the slide, it won't appreciably affect jetting.
If the needle is worn and the needle jet is made of brass, you should inspect the needle jet for wear - especially if there is a problem with excess richness at low rpm. See Needle Jet Wear.
|Emulsion tube rattling
If the needle is prevented from rotating when installed, the needle will often show wear or at least a "witness mark" on one side of the needle. Usually, it's not the most significant wear area - with other areas of the needle or the needle jet being much more significant, as far as wear causing excess richness is concerned.
Steps in the needle, as manufactured, do increase wear in needle jets and also cause part throttle inconsistencies.
Emulsion tube damage (tip):