September 17, 2014

Converting Nsr250 carb needles to adjustable.

There is an issue with the stock Nsr250 carburetor needles, the clip position is fixed and cannot be altered. This is fine for dead stock engines but may cause some troubles if any modifications have been done to the engine, e.g exhausts, derestriction of the PGM unit, opened air filters etc. 
Of course, it's still far away from owning the complete HRC jet kit but a good option for people with mild tuned bikes. Anyway, let's make some chips... 
The fixed clip removed...

The fixed clip was positioned at 1.8mm from top of the needle and Keihin needles have clip positions about 0.8mm apart. So, I made three groves in total. That is, one groove for a leaner position, stock position and one richer position. For the grooves I used an HSS lathe tool grind to the correct dimensions for stock Keihin clips. 
 And here is the end result...

As the fixed clip was thicker, a washer should be welded or pressed to the needle holder to accommodate for the thinner Keihin clips. Otherwise there will be some float on the needles. 
Well, that's all... have fun.

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