Spark Exhaust Bent Tube 180° U-Bend Ø 45 × 1.0 mm Stainless Steel Universal G9115

A full U at forty-five millimetres. One of only two diameters Spark bends through a hundred and eighty degrees, and a part that replaces two right angles and a weld.

Key Features

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

Where a Run Doubles Back

Underseat exhausts, tight two-into-one work and the crossovers on some V-twins all need the pipe to turn completely around in a space where nothing else will fit. That is what this article is for.

The alternative is two ninety degree bends with a straight between them: three pieces, two welds, more length and a wider U. Where the room exists, the pair is more adjustable. Where it does not, only this works.

Fixed Width, and Why That Is Fine

The gap between the two legs of a U-bend is set by the tooling and cannot be changed. That sounds like a limitation and rarely is: the reason a run doubles back is almost always a physical obstacle, and the tightest possible U is what clears it.

If the design needs a wider U, that is the case for two right angles instead.

The Most Demanding Bend to Form

A hundred and eighty degrees is twice as much forming as a right angle, on the same wall and the same mandrel. The outer heel stretches further and thins more; the inner heel has more material to compress without folding.

It is the reason Spark makes this angle in two diameters rather than fourteen, and the reason a workshop bender will not produce one at all.

Cutting a U Into Two Corners

Cut at the apex and a U-bend becomes two right angles, each with one straight tangent. On a build that needs two corners in the same plane, one article can supply both — and at fifty-one euro against two bends at thirty-eight, the arithmetic is worth checking before ordering.

Draining It

A U installed with the bend at the bottom is a trap: condensation collects at the low point and sits there between rides. On a road machine that is where the system rots from the inside. Where the layout allows, install the U with the curve uppermost, or drill a small drain at the low point.

Ordering

One bend per article. Spark also builds 30°, 45° and 90° at this diameter, and a 500 mm straight length under article G9002.