On Wed, 8 Aug 2018 10:24:40 +0100, "Dan S. MacAbre"
wrote:

T i m wrote:
Hi all,

Trying to help a mate with an old but cherished Kawasaki ER-5 (500cc
twin).

Long short, as soon as you turn the fuel ('Prime') on it floods both
carbs.

Now, I'm very familiar with carbs and float jets etc so I've done most
of the usual stuff, and this is after the local bike shop has done the
same for him and suggested it needs a pair of good second hand carbs
(because the float valve seats may have worn oval?).

Now, it's only done 35k miles and the carbs seem in very good fettle
generally (throttle butterflies neat and tight, slides run freely etc)
and even with new float needles and the float heights set to stock
(17mm) they still leak (out though one of the jet holes and the carb
mouths). Even lowering the float heights to the max (19mm) doesn't
seem to help matters?


Wouldn't you need to raise the float heights?

Yes / no, I think this is just a terminology thing Dan.

The spec says 17 +-2mm so 15-19mm. We initially set them to 17mm and
that is really the *distance* (not 'height' as such) between the
bottom of the float (when the carb is the right way up) and the body
of the carb, when the float is dangling such as to *just* close the
valve. So making that a bigger number will cause a lower fuel level (I
believe). ;-)

I had an Amal concentric on me old Tiger Cub, and that had a punctured
float, but you've already checked that.

The best we can Dan. Luckily the floats are hollow plastic,
translucent and made of two 'sides', and neither side on neither
floats are leaking that we can tell?

I'd only add that the puncture
was tiny, and you couldn't hear the petrol splashing about.

Yes, I have experienced that in the past, confirm we tested for that
(sploshage) and couldn't sense any at all.

The floats
weren't clear like yours, though. In those days, there was a metal tab
that you needed to bend up to make the adjustment.

Same now days. ;-)

Maybe the floats have 'shrunk' with age and become denser?

I'm at the point where I'd consider anything possible!

Everything
else (blowing in the pipe while they're upside down) makes it sound like
they would be fine as long as the float lifted properly.

Precisely. The only issue I can think of with that test is that the
weight of the (very light) floats when upside down in air may offer a
grater closing force to the jets than the floats floating in petrol
(but really)?

snip

Apparently these Kawasaki ER-5's (and other makes and models no doubt)
suffer with issues of the automatic (intake vacuum driven) fuel taps
not closing fully / intermittently but I've only ever turned the fuel
taps of my motorcycles off when I've finished using them that day, not
because not doing so will see them flood? ;-(

Ok, I think the carbs on my old 'Airhead' BMW's have been know to
flood but all that does is soaks your boot, not flood the engine /
crankcase / airbox and a quick clean (and the float bowl clips on,
making that a roadside job). ;-)

Cheers, T i m