Petrol tank breather


Well-known member
UKGSer Subscriber
Feb 27, 2002
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I'm still trying to rectify my overly odourous Adventure.

Whenever I stop the bike there is a smell of petrol.

The source of the smell has been traced - the tank breather (from the rollover valve). Petrol fumes pour out of the breather.

All other fuel lines have been replaced/tightened and are not leaking.

The breather hoses have also been replaced and the hose is dry, except:
whilst it is venting the high petrol content of the fumes condense around the end of the breather making it wet with paid for unleaded. This isn't normal!

I am 99.9% sure that there is no leak in the system (the inside of the hose is dry). It is just that for some reason I seem to have an over active breather.

Next stage is to buy a new rollover valve (although I can't see what effect that would have - it should be open anyway normally).

Once the engine has cooled the venting stops and no more smell.

Any thoughts on why my bike is pumping out so many fumes?

Thanks in advance. I'm going to beat this!
OK I'm going to be positive about the lack of replies - it means that I must have everything covered, nothing obvious that I've not thought of. Good.
I thought someone might pull me up on the 99% comment, so I made it 100% by swapping the rain water hose and breather hoses over (at the filler/rollover). Fumes still coming out of breather (was rain water hose). So proved no leaks then.

I have now installed a new rollover valve (no stock in UK) using two new clips (no stock in UK!) and guess what? B****y thing still stinks of petrol. Again traced solely to the breather hose.

So if nothing is wrong with my hoses, lines, rollover valve, clips etc etc then what is causing my tank to vent like it does (ie when parked up with hot engine)?

Is my engine running too hot? - never gets higher than half way on display.
Should the Adv tank have a heat reflective sheet on the underside? Mine doesn't.

When I'm parked up with a load of other GSs mine is the only one that smells of petrol - so it's not a case of "they all do that sir". My bike has a problem.

I had a strong smell of petrol the other day!

I traced to me not closing the filler cap!!!!!!!!!!!!!!!


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