Sucking noise from filler cap.

[Skippernick]

Washed the bike this afternoon and as i washed the tank and got water over the filler cap i heard a lot of bubbling/sucking noises.
Anyone else had this?
Leading a group ride tomorrow and don't want contaminated fuel, grrrrr.

[joebloggs]

Your tank has an breather in or around the filler cap, chances are what you heard was your petrol vapour venting, especially common if you use hot water to wash your bike.

[Skippernick]

Ooh good reply it was hot water, well warm like i could put me hands in it.
Not so worried now, although have never heard it happen before.

[taylor]

I had it only once when I trained the English rugby squad, there was a lot of spluttering going on there, my advise is give them a few leak,s,,

[Skippernick]

He he.


After yesterdays results i would be keeping my head down.
Two keys players possible out of the world cup and only really just getting past Italy……………..

[Fazerider]

The tank breathes via the filler cap, when closed it should seal to the breather pipe which goes through the tank and exits to a hose on the underside (or funnel for more recent versions). If you're getting bubbling noises it means there's a blockage so you have the risk of fuel starvation if the tank gets sufficiently depressurised, it also increases the chance of water getting in the tank.

[Skippernick]

Ah, ok ill investigate.
Rode it 100 miles today and was ok, but may explain the hard starting, which has been an issues since it was serviced which involved valve check and card sync. Thought it was idle was too low.

[taylor]

I am of on the anthem of the seas skipper, for the world cup, so my head will be well down hope we all do well,  England included,  my the best team win and it is british,. ,

[joebloggs]

Ah, ok ill investigate.
Rode it 100 miles today and was ok, but may explain the hard starting, which has been an issues since it was serviced which involved valve check and card sync. Thought it was idle was too low.

Theres an old saying that everyone should remember. If it aint broke, don't fix it.
Every bike I've every had would do as you described in your first post and not once has it caused me or the bike an issue. And if it's the cause of your idle issue I'll eat my hat.

A great acronym when trying to resolve an issue is KISS (keep it simple stupid) See hundreds of problems can cause low idle but the chances are its just the idle adjuster so start there.

Simple first......

[Skippernick]

Ah, ok ill investigate.
Rode it 100 miles today and was ok, but may explain the hard starting, which has been an issues since it was serviced which involved valve check and card sync. Thought it was idle was too low.

Theres an old saying that everyone should remember. If it aint broke, don't fix it.
Every bike I've every had would do as you described in your first post and not once has it caused me or the bike an issue. And if it's the cause of your idle issue I'll eat my hat.

A great acronym when trying to resolve an issue is KISS (keep it simple stupid) See hundreds of problems can cause low idle but the chances are its just the idle adjuster so start there.

Simple first......

I agree and know its idling to low and how to fix that. The problem i mentioned was that since its service it seems to be harder to start, i.e. it spins over for a while before catching. In 5 years of ownership it has never failed to start, but i have never quite got the knack to start it first time regularly.

[joebloggs]

Ah, ok ill investigate.
Rode it 100 miles today and was ok, but may explain the hard starting, which has been an issues since it was serviced which involved valve check and card sync. Thought it was idle was too low.

Theres an old saying that everyone should remember. If it aint broke, don't fix it.
Every bike I've every had would do as you described in your first post and not once has it caused me or the bike an issue. And if it's the cause of your idle issue I'll eat my hat.

A great acronym when trying to resolve an issue is KISS (keep it simple stupid) See hundreds of problems can cause low idle but the chances are its just the idle adjuster so start there.

Simple first......

I agree and know its idling to low and how to fix that. The problem i mentioned was that since its service it seems to be harder to start, i.e. it spins over for a while before catching. In 5 years of ownership it has never failed to start, but i have never quite got the knack to start it first time regularly.

I still think you need to be looking elsewhere. If, by chance, there is an issue with a partially blocked tank vent causing starvation issues its more than likely that your problem would be at higher rev's when the engine requires more fuel.

If its running well generally then try different throttle/ choke settings when starting from cold and see if that helps. If its hot starts that are the problem it could be down to evaporation due to heat from the engine. Either way, if it never fails to fire I'd be inclined to just leave it alone.
Your choice of course

[Jules-C]

If you can open the filler cap when you stop to but petrol in with no problems the breather is OK.  I once accidentally kinked the breather hose putting the tank on and the next time I went for petrol the filler cap felt like it was welded shut I thought the lock  was broken even tho the key turned easily I eventually managed to get the cap starting to lift and there was a rush of air into the rank, after working out what happened I'm surprised the base of the tank wasn't bent up with the vacuum in the tank.  If your petrol pump is working OK a blocked breather isn't a problem!

What choke/throttle settings do you use for starting?  No choke, press starter and then twist throttle open to about 1/4 or 1/2 open while engine cranking over usually works unless temperature near or below freezing. Once started a little bit of choke can hold the tickover up while you put helmet gloves on but moment you start moving put choke completely off. 

My old Kawasaki needed full choke to start and some choke on for about the first mile, it took me a while to get used the Fazer not needing choke and cutting out at first set of lights if the choke was on

[BBROWN1664]

Under the tank there are a couple of breather pipes that can get kinked when you lift/lower the tank. This then causes a vacuum in the tank to be created when you run the bike.
The fuel cap itself should not be sucking in any air and if, after a run, you open the tank and get a hiss this is definitely caused by the breather pipes being kinked or blocked.

Lift the tank and have a look at then first.

[Skippernick]

Just filled up and had no problems opening the filler cap so maybe not that.


Don't use the choke until its very cold. Maybe its just me, when i get some time i'll lift the tank to have a gander and adjust the idle as well.