Spark Exhaust Bent Tube 90° Ø 54 × 1.0 mm Stainless Steel Universal G9109

Fifty-four millimetres through ninety degrees. The corner immediately after a litre-class collector — the one with the least room and the most heat in the whole system.

Key Features

• Mandrel-formed 90° 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 G9109, made in Mantova, Italy.

The Corner Nobody Has Room For

On a big four the collector sits close to the engine and is surrounded by things that cannot move: the swingarm pivot, the shock linkage, the rear brake master cylinder. The pipe leaving it usually has to turn hard, immediately, in a space measured in centimetres.

That corner decides whether a one-off system is possible at all. Everything after it is comparatively easy, which is why it is the piece to mock up in cardboard first.

Mocking It Up Before Ordering

Cut the outline of the bend from stiff card, including the straight tangents, and hold it where the pipe has to go. Five minutes of card answers a question that a drawing usually gets wrong, and the article cannot be shortened in any useful way if the answer turns out to be no.

Why Not to Reheat It Straight

The material in a formed bend has been work-hardened unevenly, and heating it to red to persuade it into a different angle undoes that unevenly too. The result is a soft patch on the outer heel, exactly where the wall is already thinnest from forming.

If the angle is wrong, cut it and rejoin. Never bend it further.

Two Mounts, Not One

A right angle carrying the weight of everything behind it needs support on both sides. One mount turns the bend into a hinge and puts every vibration cycle through the tangent weld; two make it a beam. At least one of them should be rubber-isolated.

Passivating After the Weld

Pickling paste removes the chromium-depleted oxide band beside a weld and lets the passive layer reform. On a bend right off a collector — hot, wet in winter, and never cleaned — skipping it is what turns a stainless system rusty in one season.

Ordering

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