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General Category => General Discussion => Topic started by: Dirk_S on June 11, 2026, 05:14:18 PM
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What purpose do double-walled headers provide besides preventing you from seeing blue pipes? Would my V9 cafe suffer consequences if I cut off the outer pipe?
Edit: The “why”: I’m assuming that the outer wall is stainless, which leads me to presume the inner pipe may be as well. Would be nice to shed weight and get to a bare stainless.
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Yes, aesthetically, the outer covers prevent you from seeing the thin blue/gold/rust colored exhaust pipe. Similar to removing the side covers on the bike or the outer door skins on your car.
Functionally, the exposed exhaust pipe will shed heat much faster and 'could' hurt exhaust gas scavenging.
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Double wall headers are more than aesthetics, Double wall header help keep exhaust temperatures high by trapping heat inside the primary tube, exhaust gas velocity remains high. This improves overall scavenging.
I cannot imagine the weight savings being all that much omitting the outer jacket as the exhaust tube is very thin and small diameter making t pretty lightweight stuff to begin with. You might shave to a few ounces per linear foot?? The down tubes to the collector or H-pipe are the only double walled portion making it maybe 18 inches each side is double walled? That would be like throwing a deck chair off the Titanic hope in would sink slower.
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My V7 Classic came with double walled headers. Not only did the outside discolour & pit eventually, but the tack weld stabilising the inner pipe failed in due course, resulting in a constant rattle. The usual fix was to drill a hole through the outer pipe (from the inside to hide it) & tack weld it again.
My pipe was so far gone, I replaced the headers with the Agostini stainless ones available back in the day. They are single walled & a little fatter, and a lot easier to clean & polish. Every so often I remove the whole system & polish up on a wheel. They do start going brown again almost immediately, of course. If I had sprung the extra dollars for the titanium ones, they would be going blue instead of brown.
It seemed to me at the time that the bike ran better with the Agostini pipes, but that could well be influenced by their cost.
If or when I have to replace the pipes for some reason, I would prefer to have the pipes made up in steel & have them ceramic coated (properly in the ovens).
I did manage to clean up the original headers - assiduous application of a slap disc on the electric drill took the surface back to the metal.
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Hardly worth it to save a pound or so but Jet Hot ceramic coating is supposed to give a similar insulating effect to keep the gasses moving using a single wall pipe.
Pete
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I had a few exhaust parts/covers ceramic coated. Absolutely love the result. A local powder coater did them. I'd absolutely do it again if need be. My parts were flat/satin black. No idea how other colors would come out. But the black is terrific.
Not having a cup, or a second cup, of coffee before a morning ride would likely save more weight than removing a Moto Guzzi exhaust cover.
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It seemed to me at the time that the bike ran better with the Agostini pipes, but that could well be influenced by their cost.
Kudos to you sir!
One of the most honest statements I have ever read on the internet. Once we spend our money, we can easily rationalize that our money was "well spent" due to our superior judgement.
Been there, done that... many times!
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My V7 Classic came with double walled headers. Not only did the outside discolour & pit eventually, but the tack weld stabilising the inner pipe failed in due course, resulting in a constant rattle…
Malik, I thought pre-V7 III used single-walled headers. Or were yours aftermarket?
Regardless, I suppose I’ll hold off trimming down the chunky bastards.