Norton 650SS blueing pipes

There can be several reasons for exhaust pipes going blue.

If they are cheap pattern items then the thin tubing and micro-thin Chrome coating will be top of the Blues list.  If they are only blueing in a couple of places then this could be a weak mixture or bad ignition timing.  I don't think the E5 fuel is a likely cause.

I bought a cheap set of pipes that went blue after just 20 miles.  The replacement set had better Chrome but broke at the head flange after 200 miles.

See attachments......

When I fitted brand new exhaust headers to a couple of my motorcycles, I thought I'd try 'Kreem Blue Shield Exhaust Pipe Blueing Protectant' (circa £23.00 for 1 pint). I sealed one end of the pipes, poured-in a dose, sealed the other end and shook the pipes occasionally for a few hours and then drained and allowed to dry - I repeated this a few times and then left the pipes for a few days prior to fitment. I found with both bikes, the exhausts did not blue during my subsequent (albeit short) period of ownership. I must point-out that this treatment is only suitable for brand-new, unused exhaust pipes as, as soon as the internals are contaminated with carbon etc. the treatment won't adhere and thus work.

Just my experience you must understand ... .

My first Commando when it had Amals just gave a slight tinge to the pipes. Fitting a Phoenix SU carb sent the pipes blue in five minutes. Same result 35 yrs later to my current Commando, fitted and SU and instantly blued pipes. Some bikes blue their pipes, others don't, Worked on a 1956 ES2 last year that had a blue pipe (monoblock carb), another in the club, a Pemberton 530 Model 50 that hasn't blued its pipe (concentric)

Original pipes could have been double or triple plated which might or might not have kept the blueing away. Replacement pipes can now just have the chrome plated direct onto the steel. Then there is how the pipe is fitted to the head, just how much of a heat path the pipe flange has in allowing heat from the pipe to travel back to the head itself, not a good thing to have. (read Tuning for Speed, page 26) Understanding that will show that having blued pipes is not a bad thing to have. It shows that the waste heat is getting removed from the engine. An internal heat barrier (a ceramic wash like the Kreem blue shield) will reduce the pipes temperature, help prevent blueing 

I've found it very difficult to discover what process is going on.  I put a shiny new nickel plated pipe on my big Single and accidentally ran it too far retarded for a few fast miles.  My nice new pipe was depressing black.

When I got back (and corrected the timing) I polished all the black back off using Autosol.

When chrome pipes go blue, it is permanent.

It seems the reason is that the famously thing layer of chrome is traditionally put onto nickel plate.  The nickel gives the shine, and chrome makes it look silver.

But chrome is porous enough to allow oxygen through, and a nickel oxide forms below it.  The hard chrome plate stops it from being polished away unless you remove the chrome first.

The solution (it seems to me) is to order pipes with nickel but not chrome.  And don't polish too hard too often. 

My Inter has nickel plated 'silencer'.  It gets caked with burned on caster oil.  Every so often I clean it with a rubber brush and dilute caustic soda.  It comes up like new, and I never polish it.

Maybe the caster oil is the secret?  

Caustic soda (I believe) damages chrome plate, but is safe on nickel.

Rubber gloves, goggles, bucket of water in case of accident, and don't get it on anything else.