Why won't it start?

It's a well-known phenomenon, and has always been thus, not related to
'modern' petrol at all. Standard part of pre-flight checks on small
aeroplanes, for instance, to open a drain cock and let the water out
before you even get into the pilot's seat.

 

Many years back, my mechanic drained a couple of pints of water from the
bottom of my Diversion's petrol tank after it broke down and the AA
couldn't find anything wrong.

Seems it had settled in the reserve bit of the tank, so only became an
issue if you were well into the reserve supply - which it why it never
surfaced until the day I was rushing to get home and couldn't be arsed
filling up.

 

That's not suspended water. That's just water at the bottom of the tank,
being denser than petrol.

The difficult bit to believe is that crn's petrol had ~10% water in a
suspension or emulsion without it being noticable.

 

It was probably in the bottom of the tank anyway - the result of
condensation settling on the sides of the cold tank then running down
into the petrol. Still doesn't show that the petrol has 'gone off' or
that the fuel was like that when you bought it.

 

It's in my Dad's garage. I'll bring it here when my Herald has been
restored.

I liked both. The black suited it better, but the red is more shiny!

 

This is a serious matter. You are doubting Bear's very eyes.

 

Who said 10% ?.
Around a quarter of an inch (ICBA to go out and measure in the dark) in
the bottom of a gallon plastic container[1] is rather less than that.

The Bantam has been giving grief if left standing for a few days, when
I carefully removed and examined the carb there were water droplets in
the bottom of the main jet cover. Draining the tank did not reveal any
water until it had been left to stand for 4 days so the water must have
been suspended in the fuel and then settled out. My guess is that the
shaking of a short ride would have mixed in in again.

I have no idea where the water came from, maybe it came from the pump,
maybe condensation, maybe rain getting in around the fuel cap, who knows.
The petrol tap takes fuel from very low in the tank so it would only
take a small buildup of maybe a quarter of an inch for it to get down
into the carb.

Most modern bikes have a reserve setting so the main setting would be
drawing fuel from a bit higher in the tank so the Bantam is maybe more
sensitive to this problem.

[1] Originally contained parafin, about the same shape as a gallon
metal can of oil.

 

Does it matter ?. The symptoms of difficult starting are the same and
many cases of "stale fuel" could actually be a drop of water in the carb.
The cure is also the same - clean the carb, empty the tank and refill
with clean fuel.

 

The pope has admitted making a mistake.

 

I haven't professed an opinion about the life of petrol.

 

Ye dinnae look that bonnie tae me, laddie.

 

They do? Not IMLE, my shite old bonneville has but the more modern
stuff has just had a warning light come on.

 

I suspect that you are neither bonnie, nor a prince.

 

I don't think I did, you know.

 

Oh. I always took the two things to be synonymous - going off is when
the volatiles evaporate and leave the varnish.

 

Yebbut there is a long intermediate period where the most volatile bits
go quite quickly, the moderately volatiles gradually go next, and in a
matter of years you eventually end up with a residue that smells like
turpentine. It is a long gradual process during which the remaining
fuel gets more and more difficult to start because the most volatile
parts are the easiest to ignite.

 

I thought going off was when you checked the level of the fuel in the
tank using a naked flame.

 

Yes. I. Know.

 

Yes, I know you know. My comment was for the enlightenment of certain
thick sods who deny that such a problem exists.
No personal offence was intended.

 

Naah, no way.

It must be at least 20.