Skip to main content
000000 000003 000006 000009 000012 000015 000018 000021 000024 000027 000030 000033 000036 000039 000042 000045 000048 000051 000054 000057 000060 000063 000066 000069 000072 000075 000078 000081 000084 000087 000090 000093 000096 000099 000102 000105 000108 000111 000114 000117 000120 000123 000126 000129 000132 000135 000138 000141 000144 000147 000150 000153 000156 000159 000162 000165 000168 000171 000174 000177 000180 000183 000186 000189 000192 000195 000198 000201 000204 000207 000210 000213 000216 000219 000222 000225 000228 000231 000234 000237 000240 000243 000246 000249 000252 000255 000258 000261 000264 000267 000270 000273 000276 000279 000282 000285 000288 000291 000294 000297 000300 000303 000306 000309 000312 000318 000321 000324 000327 000330 000333 000336 000339 000342 000345 000348 000351 000354 000357 000360 000363 000366 000369 000372 000375 000378 000381 000384 000387 000390 000393 000396 000399 000402 000405 000408 000411 000414 000417 000420 000423 000426 000429 000432 000435 000438 000441 000444 000447 000450 000453 000456 000459 000462 000465 000468 000471 000474 000477 000480 000483 000486 000489 000492 000495 000498 000501 000504 000507 000510 000513 000516 000519 000522 000525 000528 000531 000534 000537 000540 000543 000546 000549 000552 000555 000558 000561 000564 000567 000570 000573 000576 000579 000582 000585 000588 000591 000594 000597 000600 000603 000606 000609 000612 000615 000618 000621 000624 000627 000630 000633 000636 000639 000642 000645 000648 000651 000654 000657 000660 000663 000666 000669 000672 000675 000678 000681 000684 000687 000690 000693 000696 000699 000702 000705 000708 000711 000714 000717 000720 000723 000726 000729 000732 000735 000738 000741 000744 000747 000750 000753 000756 000759 000762 000765 000768 000771 000774 000777 000780 000783 000786 000789 000792 000795 000798 000801 000804 000807 000810 000813 000816 000819 000822 000825 000828 000831 000834 000837 000840 000843 000846 000849 000852 000855 000858 000861 000864 000867 000870 000873 000876 000879 000882
English French German Italian Spanish

Exhaust pipe bluing

Forums

My left side pipe is very yellowed and has significant bluing patches...probably a result of the previous owner running that cylinder a bit too lean. Who has successfully removed it? How?

 

Permalink

Hi,

Autosol has a liquid abrasive polish for use on chrome or stainless steel specifically for removing bluing or stainless brown staining.  It requires quite a bit of effort, but does work well with perseverance - an electric mop speeds things up.  The drawback is that it works by abrading the surface and if repeated often, or the chrome is already thin, it will eventually break through to the nickel.

Thin-walled tubing seems to suffer more from bluing and a lean mixture making the cylinder(s) run hot will not help.   Japanese double-skinned downpipes were one solution but heavy, and internally ceramic coating the pipe after plating to insulate it from the gas temperature is another option - at a price.  I had been told by a plater (S&T) that when first fitting newly chromed downpipes, to start the engine allow it to get up to working temperature, then shut it down and allow the pipes to cool completely before starting again;this was supposed to prevent future bluing.  I have not got to the engine running stage of my rebuild to try that yet, but plan to give it a go; it cannot do any harm, but I cannot help thinking it is just an old wives' tale.

Andy

Permalink

The very word 'chrome' denotes the multiple colours available from chromium oxides. Since cosmetic chrome is essentially only a microscopically thin transparent layer over the silvery nickel plate, any abrasion will risk removing it altogether. I'd like to remove the blue from my 16H. If someone not associated with the snake oil sellers has a solution, I'm sure we'd all be using it.

Permalink

I regard some exhaust blueing as an indication that the bike is used and used properly. If viewing a bike with immaculate shiny exhaust pipes, I would wonder if the engine is a runner or if so, if it has ever had more than a potter round the block. You used to see well thrashed Vincents where the exhausts were blued right round to the join but not any more. Too precious. A shame. 

But that's just me.

Permalink

Discolouration of the exhaust pipes near the exhaust outlet on any bike is perfectly normal. In fact its one of those fundamental science/physics things that occur when metal is heated and there is nothing that can be done about it. To be boring it is caused by the very hot exhaust gas heating the bend. The blue colour suggests that the temperature is somewhere in the range between 500 to 750 C range. A dark straw colour is somewhere around 200 to 400 C range if memory serves. These colours were used by blacksmiths as a guide when smacking bits of hot metal about on anvils, or for us more mature types when sharpening cold chisels and when hardening and tempering things in engineering workshops and the like.

As already mentioned if the exhaust it nice and shiny chrome it's either brand spanking new or it has not been used that much. 

 

Permalink

When I ride to Vincent meetings, I see a lot of them, some shiny pipes, some blue. Mine isn't blue, probably has always gone a tad rich. It's my preferred touring bike, more comfortable than any of my Nortons. Had to fit a new pipe to my Manx. Only took five minutes for it to get straw coloured, before I sorted out that it ran lean.

Permalink

Earlier in this thread Andrew stated "and internally ceramic coating the pipe after plating to insulate it from the gas temperature is another option". A few years ago I replaced the exhaust manifold and downpipes of my BSA Rocket 3 and decided to try Kreem Blueshield to see if it helped to prevent blueing. I poured the stuff in all of the pipes with one end blocked-off and 'tumbled' the pipes to coat all of the internals. I left each coat for 24 hours and then repeated the process about four further times - the end result was that the pipes and manifold remained fairly un-discoloured (perhaps a little straw-coloured). This process only works with brand-new unused pipes. It's a bit pricey - £25.00 for 16oz bottle.

Opinions vary, but I was pleased enough ...

Permalink

My Dommie has almost no sign of straw, and certainly no blue, after 20 years. My 16H went from bright chrome to dark blue in a matter of weeks. In fact it started to discolour from moment I first started it up after several decades of lay up. Side valves are notoriously hot, but the big issue at the beginning was that it was far too lean, and timing retarded, until the carb was sorted.

Permalink

I use stain magic by yoshimura it removes all blueing and straw colouring, with no effort, but then you would need to set up carbs

Permalink

Stain Magic by Yoshimura is an abrasive cream made for stainless steel exhausts and I for one, wouldn't use it on any chrome parts as it will almost certainly erode the surface.

Permalink

I have an old container of Chrome Magic which was distributed in the UK by Auto Cavityseal, Manchester. This is an excellent chrome polish which produces a lustrous finish. Is this still available? There was a version for alloy too, AluMagic.

Cheers,

Terry

 

Norton Owners Club Website by White-Hot Design

Privacy Policy