Spark Exhaust Stainless Steel Tube Ø 48 × 1.0 mm 500 mm Universal G9012

Forty-eight millimetres. Past the point where a tube is a link pipe and into the diameters used for collector sections and the run behind them.

Key Features

• Straight exhaust tube, AISI 304 stainless steel.
• Ø 48 mm outside, 1.0 mm wall thickness.
• 500 mm long.
• Fabrication stock, supplied uncut.
• Spark part number G9012, made in Mantova, Italy.

Collector Territory

On a four-cylinder engine the header runs meet at a collector and everything after it carries four cylinders' worth of gas. That section is typically between forty-five and sixty millimetres, and forty-eight sits comfortably inside that band for a middleweight.

On a large twin it works as the whole run from the header junction back.

Deburring the Inside

Every cut leaves a burr on the inner edge, and on a 48 mm tube that burr sits directly in the gas path. It costs flow, it collects carbon, and on a slip joint it stops the two pieces going together cleanly.

A round file and thirty seconds fixes it. It is the step most often skipped and the one that shows up later as a joint that will not seat.

Thermal Movement

Stainless expands roughly seventeen microns per metre per degree. Over half a metre of tube going from cold to five hundred degrees, that is more than four millimetres of growth — which is why a system welded rigidly at both ends cracks, and why Spark's own systems use sprung slip joints.

Build in one sliding joint per run and the problem disappears.

Ovality

Tube arrives round and stops being round the moment it is clamped hard. On a thin-wall 48 that matters at the joints: an oval end will not slip into a round sleeve. Clamp on a mandrel or on a wooden vee block, not in a bench vice.

Bends in This Size

Spark offers 48 mm as a ready-made 30°, 45° and 90° bend. There is no 180° at this diameter — only 45 and 50 are bent that far.

Clamp Sizes

Spark's own clamps are listed at 43.5, 47.5, 53.5 and 63.5 millimetres — sizes chosen to close around a joint rather than to match a nominal tube. A 48 mm tube inside a 52 mm sleeve sits inside the 53.5 clamp; the 47.5 goes directly around bare 48 mm tube.

Ordering

One 500 mm length per article, no cut-to-size service.