Forum

[Jim]

Looking at the chrome on my down pipe and it's discoloured and crazed with a brownish pattern. My other EFI went the same way. Is it crap chrome or because they're lean burners and thus run hotter?Are there better alternatives?

[Forrest]

Common problem it appears, just look at the pipes on a Hinckley Triumph Thruxton or Bonneville. Lean running usually does it. The Japanese solved the problem in the 70's by double skinning the downpipes. I found that the stainless steel exhausts on my old BMW R100RT also suffered from 'browning', but I always managed to remove it with Solvol. Chrome is harder to clean. There are some cleaning products around which claim to prevent this blueing or browning, but I haven't tried any yet. I've removed the Air Injector from my Thruxton, up jetted it slightly, used Solvol on the pipes and fitted finned exhaust clamps, which they say helps keep the pipes cool. Haven't had a chance to test the bike yet. Maybe fitting finned exhaust clamps to the EFI Enfield might help.


 

[Scalyback]

Same on Thunderbolt my EFI too! Shiny chrome, shitty exhaust!

[Gwilly]

Finned exhaust ring would help but not sure if such a thing is available for the EFI..

Possibly because of the O2 sensor in the way.. Why not ask hitchcocks if they have a remedy..

Definitely due to lean burn heat more than crap chrome.. Solvol is ok as is autoglym metal polish..

Mine seems to stay a straw colour around the first bend which i find ok and not too much work to keep in check.

[simon]

The crazing is caused by the difference in the expansion rates of the base layers of the chrome. Generally the first layer is copper which is used as a filler then nickel then chrome. In a high temperature situation the copper should be avoided as it expands more than the nickel or chrome. I have a good chrome plater (no cheap but good) so I have no crazing. The bluing is simply from excessive heat. Most pipes will discolour eventually especially on long runs. However as mentioned a double skin helps as does a properly tuned engine.

[Forrest]

Just noticed that our hosts sell a product called 'Blue Shield' (Page 26 of their catalogue). You apparently put it INSIDE the pipe and it helps protect against pipe blueing.

[Toddy]

My exhaust was looking pretty shabby, decided to put some gold colour titanium exhaust header wrap to cover it up all the way to the goldie exhaust, I reckon it looks great with stainless ties holding it together. and less chance of a nasty burn if you end up under the bike. They say it increases performance having the heat retained in the exhaust but I dont really buy it.