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?
If you take the cabs off, hold them the right way up and blow into the fuel line you can hear air passing though the jets and into the float bowls. That's good.
Turn the carbs over and blow into the fuel hose and you would explode your lungs before anything 'leaked'? That's also good?
Removing the float bowls and turning on the fuel sees the fuel pouring out though the float jets. Lifting the floats with your fingers to just the point where the (rubber) tip of the needle would touch the seat and the flow stops? Push harder and the spring loaded plunger in the back of the needle allows the float to travel further but the fuel is already off at that point anyway?
So, the only thing that doesn't seem to work is the floats turning off the flow of fuel when in the bowls as usual?
Now, the floats don't appear to have any leaks (and FWIW they both weigh the same at 8 grams), you can't see any fuel in them because they are translucent and don't *seem* to be in any way distorted where they might touch the sides of the bowls etc?
So, when the bike ran last it generally performed well on the road (and when it ran the few times today it sounded ok), the fault first showed itself by a raised tickover and it has been suggested that could have been fuel leaking into the crankcase (there was fuel in the oil) and vapour being blown back up into the carbs via the breathers and fuelling the engine that way (bypassing most of the carb functions etc)?
So .. I'm tending towards the thought that the floats have become distorted somehow and are sticking on the inside of the carb body / float bowl (when floating in fuel anyway) but I'm not sure how I would check that.
Or what else could it be?
It *could* be intermittent because we tested it after cleaning and calibrating by rigging up a temporary fuel tank and the carbs didn't flood at all?
Cheers, T i m