Beware of potential engine damage from bad airbox refit after service
My 800GS is starting to show black soot in the tail pipe, it's even oozing out of the canister to pipe joint!
I suspect its the air intake pipe between the air box and the carbs, since after I got the bike i saw the right hand one was not seated properly (I was able to pry that loose and seat it properly last year)...but after removing the air box completely tonight I found this 
left hand one was also not seated properly, but in the middle where its hard to see!!
The Bike was sold by Donfords to the original owner before me, they have it on record as having being serviced there the last time at 20 000km before he wrote it off and I bought it. So sadly no more warranty on the Bike; so what is one to do now about the obvious damage due to poor service workmanship!?
What's more, the spark plug sockets look weird! Anyone have any idea what is causing this? (see below). There should be nothing in there, even if the plug was not tight it should be black not reddish brown in there!?
Photos are from my 2007 K72 model F800GS
Hi Alf
Clearly you know your way around an engine. When I got my 650 Fundoro about 100 000km ago, she had a huge hole melted in the bottom of the airbox just where the back wheel chucks its muck. It took me about 10 000km to realise this and to have it fixed.
Actually, I fixed it myself with aluminium sheet and exhaust gum. Suzuki South did not clothe itself in glory on this - they told me they could not fix it, and they failed to warn the noob me about the implications of riding with the hole.
It was only later that I discovered Shane at Atlantic Motorrad. He replaced the counterbalance shaft oil seal that was causing an oil leak into the airbox.
And Brenda Buttercup is still going sweetly.
Thanks for the quick reply Alf. Although I cant imagine how water would get in through the top of the plug's pencil coils, they seal pretty tight, may have been left inside when the plugs were changed at 20k service??
The bike does not seem to be using oil yet (I guess I would see smoke coming out of the exhaust while riding, especially on deceleration when the pistons draw a big vacuum and the rings are really bad)
But you are right, the compression test will confirm how serious the damage is, I will borrow a guage and check today.
Any idea of what the compression figures should be? PSI?
From the manual
Technical data 0219 - F 800 GS
Equipment trim-level variant:
0639
Compression test pressure
When new
15 bar
Wear limit
min 10 bar
Thanks Stu, then that might mean my pots / rings are still ok!
The left one measures between 14.5 to 15 bar on repeated tests and the right one measures between 15.5 to 16 bar.
I have in the meanwhile discovered that BMW does not make oversize rings or pistons for these bikes so one cant even rebore!? Would hate to have to buy new cylinder block etc...
Anyway, happy days, I seem to be ok for now.
My 800 also gave quite a black exhaust but came out with flying colours from a few mechanics so I would assume it to be ok based on that 
Alfs, I have a owned a few 800's (still have one), I think its correct to assume that the reddish brown colour on the coil stick is water/dirt, can get in there with jet wash if not careful, but a water crossing and not cleaned afterwards is the most likely. The 800's like fresh plugs because the heat/moisture attacks the porcelain rather than electrodes, fortunately the 800's plugs are cheap so i change them every 10k.
like all modern bikes the barrels are nikisal (or similar) coated which cannot be bored, but they don't just wear out without some serious abuse.
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