Spark Exhaust Bent Tube 90° Ø 42 × 1.0 mm Stainless Steel Universal G9122

Forty-two millimetres at ninety degrees. A hard corner with a forty millimetre socket at each end — the one bend in the range that is also a coupling.

Key Features

• Mandrel-formed 90° bend, AISI 304 stainless steel.
• Ø 42 mm outside, 1.0 mm wall thickness.
• Forty millimetre bore.
• Matches Spark's 42 mm straight tube, article G9008.
• Spark part number G9122, made in Mantova, Italy.

The Corner Most Likely to Need Moving

Right angles are where a system fouls. The clearance that looked adequate on the bench turns out not to be once the suspension moves, and the corner has to be re-clocked or shifted along the run.

Welded, that is a job for a saw. As a slip joint, it is two springs and five minutes. On the piece most likely to be wrong first time, that is worth designing in.

A U Without a 180

Two of these with a short forty millimetre pipe between them make a complete doubling-back, sprung, adjustable in width and removable. Spark makes no 180° bend at this diameter and, with this article, does not need to.

Which Way the Gas Should Meet the Step

A slip joint always leaves a small internal step. Assemble so the gas flows from the smaller bore into the larger — pipe inside, bend outside, in the direction of flow. Reversed, the step faces upstream and the joint becomes a lip for the gas to strike.

Deburring the Socket

The inside edge of the female end wants a light chamfer as much as the male pipe does. A burr in the socket picks up the incoming pipe, scores it, and is the reason a joint that went together once will not come apart cleanly.

Holding It for Tacking

Austenitic stainless is non-magnetic, so magnetic set-up blocks do nothing. Clamps, a vee block and a flat surface are the tools, and a slip joint at least holds itself in alignment while the tacks go in.

Matching What Is Already on the Bike

Forty-two is a size that exists because manufacturers do not build to round numbers. Where a factory header measures it, this bend meets it directly — no transition piece, no step in the bore, and no extra joint to leak.

Ordering

One bend per article. Spark builds 30°, 45° and 90° at forty-two millimetres.