carb drain question

[Dave48]

[quote author=BBROWN1664 link=topic=21141.msg242779#msg242779 date=1475250261]
Petrol is NOT hydroscopic. Hydroscopic things absorb water. Petrol floats on water which is why some petrol tanks have rust holes in the lowest points.

Depending how long you plan to store it decides the plan of action.

If only a few months, fill the tank to the brim to stop any moisture getting in through the breather tubes etc and just leave it in the garage unti you want to fire it up. The battery will need to be maintained.
If it is for more than a few months, then yes, drain down the tank and coat the inside or fill it to the brim and be prepared to drain it before you want to use it again. The float bowls should be emptied too to stop any varnishing in the bowls.

Google Hydroscopic

Fuel will attract water molecules out of the air which will not mix but settle at the bottom of a tank mixing with oxygen to create rust.
Short term no harm but long term, rust

Water sinks in petrol which is why petrol floats on water.
[/quote]


If you really want to be pernickety the word is HYGROSCOPIC (from the ancient Greek).Yes they had a word for it before FAZERS were dreamt of :lol


There are 3 possible factors involved in water collecting inside fueltank:


1 Rain water entering past faulty fuel filler cap seal
2 Water condensing out of atmosphere due to temperature difference between air surrounding bike and air inside tank
3 Water vapour absorbed by the ethanol content of modern fuels(5% at present increasing to 10% eventually)


If you are going to store the bike for any length of time-say over winter-then it makes sense to either brim tank & add a fuel stabiliser so that bike will hopefully restart on this fuel after lay up, not forgetting to drain float bowls to avoid residue build up & damage to rubber seals OR, alternatively, empty tank and remove from bike, invert & swill some 2-stroke oil around inside-not sure how good this procedure is for fuel injected bikes with fuel pump built into tank itself?(Someone on here will know).


The bottom line of course is that the fuel tank is one of the more expensive components on the bike & well worth a little effort to avoid corrosion issues-doesnt take much to block filter & jets with consequent frustration,expense,poor running issues.


There are well publicised  articles on winter layup/long term storage of bikes.