With the hose off there’s no way I can blow air through the little stubby pipe brazed to the top of the tank, is this normal? I’ve even tried to push net curtain wire through, it goes in to around 50mm then stops. I’ve taken the aluminium valve off that’s inline with the tube and found it was blocked but now passes air through with a little resistance in one direction. There’s a little arrow stamped on it, which way should it face? Cheers for any pointers.
My problem was with my rs 250 and I had to work hard to clean a really hard white residue out of the pipe I needed to keep turning a 3 mm drill bit by hand till I cleared the blockage and then could blow air back through the system
The one way valve will actually let air go through both ways, at least mine do, more one way than the other mind. The tank has 2 tiny holes inside it, the breather is a box welded on top. So when you poke something in, it hits the top of the tank. If you get a small mirror, you may be able to look inside the tank and see the holes. They are near either side of the breather rectangle. I hope this makes sense. You should be able to blow a little air into the tank, but not much due to their size.
That makes sense, I can blow air into it and as pressure builds it rushes back when you stop. There is a strong smell and taste of fuel. I was expecting to be able blow air through it constantly with the fuel cap open, this is not the case.
Thanks, I’ll reassemble that way, it was fitted the other way round ie arrow pointing back towards the tank when I took it off. Are you able to blow air through the small pipe in to your tank? I’m starting to think this could be the reason why the bike has been stalling , starvation of fuel caused by a blocked breather pipe from when it was repaired. Coupled with the vent valve fitted the wrong way round.
The wire goes in to around 50 mm before it stops Not wanting to force this, so what I really need to know is should I be able to blow air freely through it or is this an internal valve of some kind? My Haynes manual doesn’t say what goes on inside the tank.
That is a hollow tube with a bend in it.....I use a 3 or 4mm piece of strimmer line to clear them.....you may have to work at it, because they get blocked with rust and paint. You should be able to blow into the tank easily with the fuel cap open.....if it's closed you will get a lungful of petrol fumes as the pressure blows back. The breather valve in your photo is definitely the wrong way around. Don't mess around with the valve......they allow air in quite easily because there is not much resistance in the valve that way, but there is more resistance from the tank side, because it blows at about 3.5 psi....to relieve tank pressure. The release is about the same pressure as the pump for obvious reasons. It also holds back petrol which is slopping around particularly under braking.
Thanks for that, I wasn’t sure what I was dealing with inside the tank. I’ll cut some strimmer line and have a go I suspect it’s the filler used to make the repair when I took it in. Thanks for your help.
A wire coat hanger might be easier to push in if you are careful and stop if it seems wrong, once in you could try rotating it to clear as much as possible. It all depends where the blockage is really.
Tried the strimmer line trick with no joy It goes in but comes out dry, as if it coils up inside the lump on top of the tank, missing it’s target. So moved on to a long thin Allen key, rotating as I went, but as you said it felt wrong and as there’s a bend in the pipe so could only go so far. On an up note I’ve turned the valve to face the correct way and loosened the oil pressure switch in anticipation of one arriving in the post.
Just an idea, in the past on similar problem's, I've used copper wire from the type you use for cookers etc ( the thick stuff) stripped it back to bare wire, i find it holds its own when probing and might go around the bend.
I’ll give that a shot, I imagine there’s a gap between the end of the pipe and the aperture of the tank, or at least thats how it feels, and would go to explain why the strimmer line angle failed missed the target and coiled up. Stiffer will hopefully get results.. usually does!
How in hell did filler (if it is filler) get so far into that breather tube? I would try cutting the end of your pieces of wire at 45 degrees to make a sort chisel end and rotate the wire once you hit the barrier, but I think a length of coat hanger wire bent into a curve before it goes in will be best. Copper wire might eventually break and if a small piece gets stuck in there...... Just a thought though.....Open the filler cap, fit a footpump (or compressor) to the tube and see if you can blow the blockage out under pressure.
Thanks but like the strimmer line, it’s not firm enough. Copper wire and compressed air is my next shot.
