Spark Exhaust Bent Tube 45° Ø 54 × 1.0 mm Stainless Steel Universal G9108

Fifty-four millimetres at forty-five degrees. A collector-section diameter in the angle that does most of the turning on a large four.

Key Features

• Mandrel-formed 45° bend, AISI 304 stainless steel.
• Ø 54 mm outside, 1.0 mm wall thickness.
• Straight tangents at both ends.
• Matches Spark's 54 mm straight tube, article G9003.
• Spark part number G9108, made in Mantova, Italy.

The First Corner After the Merge

On a litre-class four the collector is large, hot and close to the engine, and the pipe leaving it has to get past the swingarm pivot before it can do anything else. That first corner is the one with the least room and the most heat, and forty-five degrees is usually the sharpest turn that will fit.

Heat Near the Bend

Immediately after a collector the gas is at its hottest, and a bend there will radiate onto whatever is behind it — a shock body, a wiring loom, a coolant hose. Check what sits within fifty millimetres before the run is committed, and plan a shield rather than discovering the need after a melted connector.

Growth Along a Hot Run

Stainless expands about seventeen microns per metre per degree. The section right after the collector sees the largest temperature swing in the system, so if there is one sliding joint in the exhaust, it belongs downstream of this bend rather than upstream of it.

Bracket Placement

Not on the curve. A tab welded to the outside of a bend puts a hard point on the thinnest, most stressed part of the tube. Weld to a straight section and let the bend float between two supported points.

Filler and Technique

308L for AISI 304, square cut, tight gap, clean metal. The low carbon content of 308L is what stops chromium carbide forming at the grain boundaries — the difference between a joint that lasts and one that rusts along the heat-affected zone within a season.

Clocking It Right

A bend has a plane, and rotating it about the tube axis swings the far end through an arc. On a run with a collector at one end and a fixed mount at the other, that rotation is the only adjustment left — and it has to be right before the first tack, because afterwards the only correction is a saw.

Ordering

One bend per article. Available in 30°, 45° and 90° at this diameter.