Spark Exhaust Bent Tube 45° Ø 70 × 1.2 mm Stainless Steel Universal G9157

Seventy millimetres at forty-five degrees, in a wall a fifth thicker than the sizes below. A genuine corner at a diameter where most benders give up.

Key Features

• Mandrel-formed 45° bend, AISI 304 stainless steel.
• Ø 70 mm outside, 1.2 mm wall thickness.
• Thicker wall than the 32 to 60 mm bends.
• Matches Spark's 70 mm straight tube, article G9009.
• Spark part number G9157, made in Mantova, Italy.

A Sharper Turn in a Large Section

At seventy millimetres a forty-five degree bend is a substantial piece of metalwork: the sweep is long, the section is large, and the assembly it belongs to is usually a box or a silencer body rather than a pipe.

Where a thirty degree bend gives a shell a gentle curve, a forty-five turns it — around the back of a swingarm, up behind a subframe, into a space the straight section could not reach.

The Limit of a Mandrel

Every mandrel has a minimum radius below which it stops supporting the wall and starts dragging it. At seventy millimetres in 1.2 mm that limit is reached sooner than at forty, which is why large bends sweep wide — not a design choice but a consequence of what the tooling can do without wrecking the section.

Room for the Sweep

Measure the arc, not the angle. A forty-five degree bend at this diameter occupies a great deal more space than the number suggests, and on a motorcycle that space is usually shared with the rear wheel.

Heat Input at 1.2 mm

Thicker material takes more heat and takes longer to reach it. Settings carried over from the thinner diameters give a cold bead that sits on the surface instead of fusing — visible as a raised, shiny line that has not wetted in at the edges.

Cutting a Large Bend Square

Half a degree of error across seventy millimetres is more than half a millimetre of gap at the far side. A bandsaw with a proper vee support beats an angle grinder here by a wide margin, and a paper template beats freehand marking.

Storage Before It Is Used

A large thin bend is easy to spoil in a workshop. Keep it off concrete, away from grinding work, and capped at both ends — embedded steel dust from an angle grinder is what makes stainless rust in spots that look like a material fault and are not.

Ordering

One bend per article. Spark builds 30°, 45° and 90° at this diameter.