Spark Exhaust Bent Tube 45° Ø 45 × 1.0 mm Stainless Steel Universal G9105

Forty-five millimetres through forty-five degrees. The angle most exhaust routing is made of, in a diameter that carries a large twin on its own.

Key Features

• Mandrel-formed 45° bend, AISI 304 stainless steel.
• Ø 45 mm outside, 1.0 mm wall thickness.
• Straight tangents at both ends.
• Matches Spark's 45 mm straight tube, article G9002.
• Spark part number G9105, made in Mantova, Italy.

Crossover Pipes

On a large V-twin, or a parallel twin with widely spaced headers, the two runs have to meet somewhere. A pair of 45° bends is the usual way of bringing them together into a collector without either pipe arriving at a hard angle.

Equal lengths matter more than short ones. Unequal primaries on a twin change the character of the engine, and not usually in the direction the owner wanted.

Fitting to a Header Flange

Where a fabricated run meets a factory header the joint is a flange or a sprung slip fit, and neither tolerates a bend welded hard against it. Leave a short straight before the flange so the joint can be aligned independently of how the bend is clocked.

It also means the flange can be replaced later without cutting the bend out.

Weld Sequence Around a Curve

Tack four points, check the assembly against the motorcycle, then weld in opposing quarters. On a bend the pull as the weld cools acts along the curve rather than along a straight line, so the distortion shows up as a change of angle rather than a step in the joint — harder to spot and harder to correct.

Two Bends and a Straight

Two of these facing the same way, with a straight between, give a right angle with a built-in offset. Facing opposite ways they give an S. Almost every routing problem on a motorcycle is one of those two shapes, and both are built from this article twice.

Springback, and Why It Is Not Your Problem

Stainless returns four to eight degrees after a bender releases it, which is why hand-made bends come out shallower than intended. A production bend has that compensation built into the tooling: it arrives at forty-five measured, not forty-five attempted.

Ordering

One bend per article. Spark builds 30°, 45°, 90° and 180° at this diameter — the widest choice of angles in the range.