White stuff...

[TigerWil]

Anybody seen this white stuff in his inlet ?

It might be the result of the 20 year old plastic fueltank that is slowly dissolving....

Anybody other ideas ?

[Sin_Tiger]

They don't really dissolve. They do manage the neat trick of morphing shape as soon as you put them on the deck and turn your back on them

Could be some effect of methanol or an additive but I'm guessing.

[TigerWil]

Could be right Sin_Tiger, but some if the needles were also polluted 

[TigerWil]

Reminds me that in some countries like France they add Ethanol to the fuel. Guess that wont be any good to the plastic tank 

https://en.wikipedia.org/wiki/Common_ethanol_fuel_mixtures#/media/File:Common_ethanol_fuel_mixtures.png

[BruKen]

Is it sooty? If so and I saw that the first thing I'd be looking at is if the intake valves were seating correctly. i.e. not worn, recessed or with incorrect valve clearance and that valve timing was correct because I'd put that as being caused by blowback if indeed sooty

[Mustang]

 
I had a gas tank for a spare that had the white crap in it but the intakes never looked like that , probably cuz the bike would die far before that could happen as all the jets were totally clogged with white gas soaked plastic like slime

[nickjtc]

If this is looking up stream from the carbs to the airbox I don't see how there could be deposits from the tank there?? Maybe its ash from the Iceland volcano that got through the air filter??

[Mustang]

If this is looking up stream from the carbs to the airbox I don't see how there could be deposits from the tank there?? Maybe its ash from the Iceland volcano that got through the air filter??

that shot is looking into the intakes from DOWN STREAM of the carbs

when if ever was the last time valve clearances were checked , and does it backfire sometimes out the intakes .cuz I have to agree with BruKen , looks like blowback from valves
A compression test will show immediately if that's the problem.

[nickjtc]

As always Mustang is the man 

[TigerWil]

Thankx for all you're answers; much appriciated 

Some others are also talking about aluminium oxidation in the carburettors 

[BruKen]

If you have had water in the fuel system the float bowls can corrode. They will block jets and coat needles but I've never seen them coat the bore of the intake like that. A common problem in mercuiser carbed engines of the 80's, but that's boats. I've not really witnessed it in bikes before with any severity. Pop of a float bowl and inspect. I still think it's a valve / valve timing issue.

[fishnbiker]

Is it a thin coating of white powdery dust? Wipes off fairly easily?

Maybe you might check the fuel specs for your location. My '95 had what looks like the same issue. Several years ago, the Yahoogroups Tiger threads tracked it down to Methyl tertiary butyl ether, (MTBE) an additive in some North American fuels.

If I remember right, it was associated with higher ethanol content fuels. It was an issue with this additive attacking the nylon of the tank & dissolving into the fuel.

Changing to a different fuel company without this additive ultimately fixed the issue, after cleaning out the carbs. Before finding it was the ethanol connection, I first solved MY problem by lining the tank with KREEM, an epoxy pour-in & swish mix to coat the tank innards. Later, changing to another fuel brand was discovered.