{"product_id":"spark-exhaust-bent-tube-90-degrees-35mm","title":"Spark Exhaust Bent Tube 90° Ø 35 × 1.0 mm Stainless Steel Universal G9131","description":"\u003cp\u003eThirty-five millimetres at ninety degrees. The tight corner in a small-twin diameter — the piece that gets an exhaust under a crankcase and out the other side.\u003c\/p\u003e\u003ch2\u003eKey Features\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eMandrel-formed 90° bend, AISI 304 stainless steel.\u003c\/li\u003e\n\u003cli\u003eØ 35 mm outside, 1.0 mm wall thickness.\u003c\/li\u003e\n\u003cli\u003eStraight tangents at both ends.\u003c\/li\u003e\n\u003cli\u003eMatches Spark's 35 mm straight tube, article G9011.\u003c\/li\u003e\n\u003cli\u003eSpark part number G9131, made in Mantova, Italy.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eUnder the Engine\u003c\/h2\u003e\u003cp\u003eOn a small twin or a single the exhaust drops from the head, turns rearward beneath the crankcase and climbs again toward the silencer. The first of those turns approaches a right angle, and it happens in the tightest space the system has.\u003c\/p\u003e\u003cp\u003eGround clearance decides how tight. Measure it with the suspension compressed and a rider on the machine, not with the motorcycle on a paddock stand.\u003c\/p\u003e\u003ch2\u003eFlow Separation on the Inside\u003c\/h2\u003e\u003cp\u003eGas going round a sharp corner cannot follow the inside wall. It separates, leaves a slow recirculating region behind it, and effectively narrows the pipe. That is where the loss in a right angle actually comes from — not from the change of direction itself.\u003c\/p\u003e\u003cp\u003eA larger radius reduces it, and so does a straight section afterwards in which the flow can reattach.\u003c\/p\u003e\u003ch2\u003eMagnets Do Not Help\u003c\/h2\u003e\u003cp\u003eAustenitic stainless is non-magnetic, so the magnetic clamps and angle blocks that hold mild steel for tacking are useless here. Set-up means clamps, vee blocks, tape and a flat surface — which is worth knowing before the first joint rather than during it.\u003c\/p\u003e\u003ch2\u003eCutting a Ninety in Half\u003c\/h2\u003e\u003cp\u003eCut at the apex and a right angle becomes two forty-fives, each with a straight tangent at one end. It is the reason the sharper angle is the safer article to keep on a shelf: the saw only works in one direction.\u003c\/p\u003e\u003ch2\u003eAfter Welding\u003c\/h2\u003e\u003cp\u003ePickling paste on the outside of the joint removes the heat-affected oxide and restores the passive layer. It is not cosmetic — the discoloured band beside a weld is chromium-depleted and it is where a stainless system starts to corrode.\u003c\/p\u003e\u003ch2\u003eOrdering\u003c\/h2\u003e\u003cp\u003eOne bend per article. Available in 30°, 45° and 90° at this diameter.\u003c\/p\u003e","brand":"Spark Exhaust","offers":[{"title":"Default Title","offer_id":53618247270666,"sku":"G9131","price":2300.0,"currency_code":"DOP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0949\/7831\/0410\/files\/6087d2fd97619_7693e1b9-a353-4267-8c97-940cf42b6664.png?v=1788348509","url":"https:\/\/inter-pace.com\/en-do\/products\/spark-exhaust-bent-tube-90-degrees-35mm","provider":"Inter-Pace","version":"1.0","type":"link"}