Bar Stock Needle Valve

needle valve
A valve closed by a thin tapering part
A needle valve is a type of valve having a small port and a threaded, needle-shaped plunger. It allows precise regulation of flow, although it is generally only capable of relatively low flow rates.
This is used to tune the fuel to air mixture on the engine carburetor. On most engines, the needle is turned clockwise to lean the mixture, and counterclockwise to richen.
Adjustment on a carburetor used to set proper fuel/air mixture. Some carburetors have separate needle adjustments for low and high throttle. Typically, turning the needle clockwise (screwing in) leans the mixture (less fuel), and vice versa.

bar stock
Bar stock, also colloquially known as billet, is a common form of raw purified metal, used by industry to manufacture metal parts and products.
The metal stock from which handmade horseshoes are forged. Typical steel horseshoe barstock is 5/16" by 3/4", but many other sizes are also used. Barstock is generally purchased by the linar foot.
Metal bars of various lengths made in the shape of rounds, squares, flats, hexagons, and octagons and from which parts are machined.