Isn't it built into the filler? There's a little rubber bit on the inside of the filler under the lid towards the front right (I think). It looks like by rights it can't possibly breathe, but it must do because there's no other way in/out for anything.

It is part of the tank cap gubbins - there is a drain and a vent under the cap?

bikemonkey wrote:Forgive my shit ability to read thread titles....

Here's the parts fiche, no idea where it is though.

http://www.cmsnl.com/honda-rvf400rr-nc3 ... ml#results

Forgiven

Looks like im missing part no. 15. Will if i can get hold of it from the local bike shop round the corner.

Watch this space!!

Part ordered from my local shop. Should be here next week.

So finally the part arrived and i got it fitted. It actually goes around one of the outer legs of the ring of the fuel cap and sits on top of the breather hole.

Theres a small part of the fuel cap which juts out and presses down on the rubber part. It looks like it has a small breather hole in it.

All this doesnt really matter though as it still hasnt fixed the problem.

The breather holes in the fuel cap itself are all external to the main rubber seal to the tank. So i am still none the wiser as to how it breathes.

Can someone post a pic of the bottom of their fuel cap and the inside of their tank please?

Thanks

Robin

Item 15 rubber fits in the tank neck and the square lug on the filler caps seals it against fuel leak.
There is a breather hole in the lug and a gap above it to allow air flow.

Exactly how mine is now. Thanks for the pics.

But its still not allowing it to breathe.

Im wondering if it might be the cap itself which needs replacing?

That would be the next logical step.

I don't think so, the cap vent is simple.
Look closely at the square lug, it vents out of the side, so check the hole is clear by poking/blowing it through.
There is also a gap at the top between the lug and deep recess in the cap.
Is the rubber air way clear?

Just to let you all know and to close off this topic finally, i got a replacement fuel cap and it appears to have solved the problem. Talk about a simple answer!!

Annoyingly, the new cap came with the little rubber breather doofer which took 2 weeks to arrive and was almost the price of the cap on its own.

Anyways, tank now breathes and the bike is back together. Once the roads are a little nicer the gal can take it for a ride.

Thanks everyone for your help.

Robin