I was out riding yesterday and pulled up at a pub for a break. While there, I noticed the inside of my pipes had a light tan colour to them. I’ve never really noticed this on vehicles before. They’re usually a sooty black, yes? What does tan mean? Is it running lean? It was Dyno tuned only a month ago. 

98, 95 or 91 unleaded?

The 98 fuels have more 'cleaners' in them which could contribute to the pipe color and you mentioned a recent tune? .
Could just be that the bike is running at optimum burn with correct VE values from the dyno rather than unburnt fuel / too rich which is not good for the bores and oil.
A check of the plugs can set your mind at ease, light gray to tan in color
Is the bike behaving normally & well?
Did you notice it after a long ride and constant throttle, eg Highway?
Unleaded fuels can show a light color in the exhaust pipe after long highway runs at cruise and then darken up (sooty)  in stop / go driving / riding
 

If the SE intake was put on after the dyno tune, Id advise that you get it checked as in re-tuned to allow for the extra air being drawn into the motor as the VE values will most likely be out. 
the ECM can only compensate so much for changes like that

Nah, I bolted on the SE and then had it tuned :-)

This is what my pipes look like after a 400k ride ,obviously the flash on the camera skews the images , but the residue is light in colour and minimal.
Some fuel additives leave different colors , i use 98 octane from any service station that is available on a ride , i would say i always try to use high turnover servos at all times purely on the premise that their tanks are being cycled regularly .
After around town use the pipes blacken up due to on/off throttle use and extended idling  ,it is not an indication of state of tune .
Tail pipe color is not to be used as a guide to state of tune ,as modern fuels leave practically no residue that can be indicative of a running/tune condition ,but i would expect pipes to be very light on residues no mater what the colour after an extended ride.
And yes they are a very light grey just like the old leaded fuel residue! and the plug porcelain reads off white/ yellow to hint of tan with no residue, the motor runs perfect as it has done since Lushy tuned it some years back,[tune was done after all mods were completed]  it even gives excellent fuel economy when used steady state at posted speeds.

heard 95 is the best fuel to use ..  when I run 98 the bike pings.. try a few tanks of 95 see what happens

I use 95
I can get 95 most places and my bike is tuned with TTS on 95
If I can't get 95, the other options are a minor shift up or down.
Don't agree with running 98. a slower burn, rarely a complete burn with the engines that we have.
All that happens is the heads and pistons carbon up.
My plugs and pipes are telling me the combustion is right where it should be.
The same with my carbed bike.
If the 98 is not turned over often enough, all the goodies are lost from the fuel anyway.

I have a friend that owns/runs his own workshop building and tuning anything that comes in the door, very knowledgeable bloke.

Now you have got me in ,,,,,  can he explain why the combustion event is incomplete?

Carbon build up has two common origins , oil contamination and too rich a mixture , i am at a loss to see how octane rating effects these. 98 fuel actually burns cleaner than lower rated fuels ,i would suspect the tune not the fuel grade , but that's just me.

I know we are not talking about cars , but if 98 is used instead of 91 the vehicle will return better fuel economy .Better combustion efficiency is one factor ,this is not a opinion it is a fact.

Cheers.

older bikes & cars, eg non efi without all the smarts to ensure optimum mixture's based on sensor burn data when running 98 type fuels can run excessively rich. it  washes bores, contaminates the oil, etc.

   

That is a tune fault not an octane fault. I ran 98 for tens of thousands + of km in carburetor Evo's for years ,never had a bore wash or carbon issue ,,,,but then again it was dyno'd ,that might have been the problem.

As a mater of fact i have used premium fuels in all my bikes i have owned since 70 ,and that is every bike , there used to be a pure benzine pump at BP Outbound Darlington  that you could have half avgas and half benzine ,made the Bonnie run just fine. I also used to work for a race team at the time and got half used BP100 drums to pour in anything i owned [including shitbox cars] and wash parts in , i still remember my hands being bone white  .Problem was lead fouled plugs .

Cheers.

There was a fuel discussion some weeks ago (with some interesting insights), haven't quite mastered the navigation of this site...suffice to say
I've been running Caltex 98, every time I use BP98 I get the same issue, I thought it was their BS advertising re two tanks and clean???

Would be nice to hear some sound mechanic's thoughts!

My Apologies Hilly/Hoodeng

When I replied to this post...it was the first one I'd Read....bad me for not scrolling through...or bad red wine...lol