Tank Slap - Motorcycle Forum

I've noticed brown soot in my end can on my bike. I'm unsure why this is. Is my bike running rich or lean, I've never noticed this before or not as brown as it is now.

Going to give it a full oil and filter change soon, parts arrived today.

Also will check my air filter to make sure it is clean.

Anything else I could check?

Any ideas of why?

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Best why to get an idea of how she is running without an analyser and a dyno is whip the plugs out and have a look at them.

The exhaust deposits on most healthy modern petrol engines seems to be pale beige these days.?
So if your tailpipe appears more like a deeper brown, that would suggest something being deposited in addition to the normal combustion residue.?
Imho the likely suspects would seem to be; too rich a mixture, or oil inclusion.

Too rich or a mod/faulty exup valve is causing fuel to be burnt in the exhaust would be my best guess without seeing it.

All not.sounding too good.

I Will give it a full oil and filter change. Don't fancy having to take out the plugs to be honest as don't want to overtighten used ones, these only got changed last year plus don't have a gauge to measure the set distance for my bike plugs.



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This is just an image from.google but it looks like this. You can wipe it off but doesn't look good!

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Rossgo wrote:This is just an image from.google but it looks like this. You can wipe it off but doesn't look good!

Does it feel greasy when you wipe it off, or dry & crusty.?

StMarks wrote:

Rossgo wrote:This is just an image from.google but it looks like this. You can wipe it off but doesn't look good!

Does it feel greasy when you wipe it off, or dry & crusty.?

Just fingered my hole

This is it. It's a dust. Not oily when wiped it goes back to normal colour. I did out some.red ex in it just before Wales ride out maybe I out too much in then I filled up with 99 shell. Could this be an issue?

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Could well be the Redex. I use to put it in my car as a kid and rev it and it was like a smoke machine at the exhaust . I would just clean it off and monitor. If you haven't made any mods and it's only just started doing it then a very good chance it could just be the Redex or possibly additives in the Shell VPower and nothing to worry about.

I'm.really hoping that's it. I only just thought about the Redex as it's not a normal thing- my dad had some and I thought to myself, Wales, long ride, at times at speed, perfect opportunity!

Going to give new oil and filter change. And check my air filter. Hoping that's still as clean as the day it went in as it hasn't covered many miles and last time.it came out it was spotless!



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I’d its dry and light, it’s pretty much normal imo

If it’s oily or heavily crusty then that indicates unburnt components and a bigger problem.

Also in addition to the redex if you’ve moved onto Shell V-Power from a cheaper fuel, the cleaning agents in the V-Power will be removing some deposits.

The oil and filter won't be related to the combustion process unless something major has gone wrong internally, like a ring has gone and then you would expect black colouring and an oily residue to be present which you don't have any evidence off.

Could run a little rich if air filter is blocked / dirty but if recently changed very unlikely tbh.

If no recent mods have be made that could effect the fuel ratio, I would be dismissing the Redex and use of VPower as the most likely causes first as ease none evasive tasks.

Yea, it's defo dry and light. It's like a layer of dust

Those pics I attached were taken this morning. Pics don't show just how bright it is though!

I usually use 97 BP Ulitmate. I'm.really hoping that's all it is. Just seems a strange colour. I understand a dark colour but not bright brown!

I shall take a little time and keep an eye on it

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Ok i was thinking that too. I can't see any evidence of oily deposits which is good. I'm expecting to see an EML on if it was bad like a piston ring or something letting in oil and a bad idol and piss poor acceleration, which I certainly don't feel!

That's for your comments.

Just took be back when I saw bright brown instead of a dark colour just looked strange lol!

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Wipe it off and fill with your regular fuel and monitor for a couple of hundred miles Rossgo and see if it comes back.

In my experience sometimes we can worry and look for problems that are not there been there don't that

Iirc from back when I was an apprentice:

Black - too rich (carbons up engine & exhaust)
Biscuit brown - Correct mixture (running clean)
Light grey/white - too lean (can burn out valve seats and spark plugs)

I’d guess your bike has the usual exhaust sensor and catalytic converter Rossgo, if your engine management light isn’t on, the chances are there’s not much wrong with your bike and it’s just a side effect of the Redex.

IMO it looks like oxidisation of the exhaust material given that it is only from the drilled/lasercut areas.

Am I right in thinking this is a standard car exhaust? ***EDIT*** I was looking at the image Roosgo got from the internet. They don't use the highest quality materials if they don't have to

It's the damp in the Welsh air, rusting yur engine from the inside.

If you’re really worried nip over to the MOT station and get them to put the probe in the exhaust, compare the reading with your last MOT and you’ll see if there’s anything odd going on. If nothing else it’ll put your mind at rest.