Spark Exhaust Bent Tube 180° U-Bend Ø 50 × 1.0 mm Stainless Steel Universal G9165

A hundred and eighty degrees at fifty millimetres. The larger of Spark's two U-bends, in the diameter most exhaust hardware is built around.

Key Features

• Mandrel-formed 180° U-bend, AISI 304 stainless steel.
• Ø 50 mm outside, 1.0 mm wall thickness.
• Straight tangents at both ends.
• One of two diameters Spark bends this far; the other is 45 mm, article G9115.
• Spark part number G9165, made in Mantova, Italy.

The Underseat Turn

An underseat system climbs behind the shock, runs forward under the tail unit and then has to come back to reach a silencer that exits at the rear. That return is the tightest part of the whole layout and there is no room in it for two corners and a weld.

Fifty millimetres is the size that section is normally built in, which is why Spark bends this diameter all the way round and stops at fourteen others.

Two Legs, One Plane

Both ends of a U leave in the same plane and point in opposite directions. That makes alignment simple in one axis and unforgiving in the other: rotate the piece a few degrees about its own axis and both legs move, together, in a way that is difficult to correct downstream.

Clock it on the motorcycle with tape before any tack goes in.

Fifty-Three Euro, and What It Replaces

Two right angles at this diameter cost seventy-six between them and need a straight, two welds and an afternoon of alignment. The U is one part, two joints instead of four, and a shape that cannot come out crooked because it was formed that way.

It is the clearest example in this range of a bought part being cheaper than the assembly it replaces.

Wall Thinning Over a Full Turn

The outer heel of a U stretches further than that of any other bend and loses more wall doing it. On a mandrel-formed part at a controlled radius that loss stays within sensible limits — but it is the reason a U should not be the section a bracket is welded to, and not the section a system hangs from.

Condensation at the Low Point

Installed with the curve downward, a U collects water and holds it between rides. That is how a stainless system rots from the inside out on a machine used in winter. Curve uppermost where the layout allows; a small drain hole at the low point where it does not.

Ordering

One bend per article. Spark also builds 30°, 45° and 90° at this diameter, and a 500 mm straight length under article G9005.