tank breathing system

big swoosh when I've opened the tank twice in the past 2 days.

Obviously it's not venting,

can anyone explain from whence to where it vents? parts book is inconclusive...

(or should that be where to whence?)

cheers guys

Hey Lazlo,

Mine is 1100 but may be similar, had the tank off recently and had to correct incorrect venting on mine with guidance from Pete.
Per linked pic, pipe (15) vents under bike to atmosphere, Both the tank cap drain and inner tank vent are joined with union (16). I found the connector (14) on the tank cap drain side (left one) on my tank was blocked solid. Your vent drain (right side) might be blocked or even more likely the pipe kinked as the space under the tank is very tight and easy to pinch these pipes when re-fitting the tank.

The connectors (14) could be in a different part of the tank on the 1200 (more towards the front?)

Mike

cheers for the wisom

so there is a drain hole in the cap and a hidden vent hole somewhere within the tank and they both drain to the same t piece somehwere under the bike?

I noticed that the bike was leaking some fuel from the drain after a fill up recently, perhaps it's crystalised and blocked the vent or something.

all sort of makes me want to jus pierce a simple hole in the cap and cover it with a bit of tin like in the old days

...or just remove the tank vent from the t piece... so they become 2 seperate systems...

1100 and 1200 tanks have the nipples for the vent and drain in different places, other than that the system is basically identical.

so the nipple on the left side (sitting on the bike) is the drain nipple?

...following up...

I checked the hoses...

the hoses from both tank nipples are totally clear.

so is my problem within the breather (rhs) nipple itself then?

(the one that is completely inaccessible without removing the tank!)


I was filling in a gas station with a dodgy pump the other day, got a good spray around the filler hole but not quite in it. could that lead to a non breathing tank?

edit --

I had a look in there,

so basically there are two tubes that run inside the tank from around the filler. The one one the left is open to the elements, somewhat, and is there for rainwater to drain. The other one has a small ball bearing check valve which allows air from within the tank out via the right hand side tube... the rainwater and the fuel vent/overflow both go to the same t piece.

ok

but in my case the right hand side ain't doing it.

seems quite an overengineered response to the idea of venting a tank.

any reason not to just put a .5mm hole in the side of the check valve plastic bit? being horizontal I don't think any rainwater would get in there... and I've never noticed too many fumes from any of the many cap venting bikes I've owned in the past.

I'd be happy to fix a blocked spigot once, but if this is going to be a recurring thing then no way!


thoughts observations etc?



cheers guys

I would suggest check the right hand nipple, it might be blocked?

On the 1100 you could get to this without removing the tank, just lifting the rear of the tank and supporting with a block of wood, but I'm not sure if its harder or easier on the 1200 to get to the nipples, The are easy enough also to remove with the correct size wrench.

The left one on mine was blocked so solid I had to remove it and use a small drill to clear it, you could also try blowing some air in or sucking air out to check if it is blocked somewhere else.

Why the aversion for removing the tank? Sure you have to undo that horrible fuel connector, but as long as you reduce the pressure (by running the motor with the pump leads undone) it's easy once you've done it a couple of times.

Tank off gives you proper access to all those gizmos hiding under it, as well as the bits you want to see under the tank.

You don't even need to disconnect the tank. There's enough length in the hoses to simply unscrew, lift, and turn the tank. Rest it on some wood placed across the frame. Or just plonk it on the cross brace at the rear of the perimeter frame.

yeah no problem with lifting the tank and propping on a block of wood, thanks for the info (I thought it was a tank off job.)

but my point was more like, how often is this likely to happen? If i fix it now, will I be back again in 6 months? etc etc I'm not sure I want to add this into the maintenance schedule if that can be avoided...

especially if there might be a more simple arrangement.

and why do they get blocked?

ethanol going hard? squatting spiders?

if it's the former then it's likely to reoccur no?

¯\_(ツ)_/¯


I've never touched mine, and never had an issue.

If it were squatting spiders, I would have had my fair share. My garage is an arachnid paradise.

_ _
\_('')_/


indeed

maybe I'll fix it this once and if it happens again I'll butcher the fuel cap!


in other news, my mistral high pipe is on the way so will be in the market for a new map soon...


cheers

I did mine recently - was blocked after 12 years of ownership. Small pin chuck and drill to match cleared it out. I suspect corrosion in the cheap brass or whatever metal the nipple is - add water
--->>> corrosion.

well, it's fixed for now,

got a syringe and some white vinegar and poured down both holes, they are both draining at their respective spgots and through the hose.

if it misbehaves again I'll update.

thanks for the input everyone

hopefully sorted for a few years more

….the rubber seal below cover plate is not sysmetric concernig the whole for the air of tank vent….

MKGuzzi wrote:

….the rubber seal below cover plate is not sysmetric concerning the whole for the air of tank vent….

Well I did have an issue like this recently with the rubber gasket that came with the every nice Givi Tank ring engineered by Onur Kuraner from Turkey.
The tank ring requires a slightly thicker rubber gasket to replace the original.

Unfortunately over ~6 months the new rubber gasket seems to have deformed causing issues, namely that I was breathing gasoline fumes every time I went for a ride,  

So only last week I removed the ring and replaced the new gasket with the original, much better! Pictures here The pictures show how the original gasket should look (Picture 3 and 5) , the newer gasket in picture 1 before fitting and in picture 5, 6 months later after removal. The fact that my cap drain was blocked and I did overfill once may have aggravated the situation. On that occasion gasoline started dripping down the side of the tank onto the valve covers as I rode from the gas station,    , but this was the cause of the blocked drain.

I have contacted Onur about the gasket and he is very kindly sending me a new gasket made from Nitrile Rubber which we hope will fix the issue. Onur is a top guy, could not be more helpful.

On my bike the rainwater drain is blocked at the bottom end. Tried clearing it with a 1mm drill by hand - gone in about 30mm now and still pulling white corrosion -
Obviously i want to avoid drilling through the pipe

So my question is - do the metal nipples go into a good thread so i could undo do it and screw it back when clear?

lcjohnny wrote:

So my question is - do the metal nipples go into a good thread so i could undo do it and screw it back when clear?

Yes they do, I had the same situation, just unscrew them with the appropriate size wrench, and then you can safely drill the gunk out of them, amazing how hard it gets!
I put them under a hot flame also to burn away any remnants.

I cleared mine on a Breva 1100 by inserting a short piece of speedo cable into one end, and then twisted it back and forth using a battery drill. A lot of gunk was removed.

kiwi dave wrote:

I cleared mine on a Breva 1100 by inserting a short piece of speedo cable into one end, and then twisted it back and forth using a battery drill.  A lot of gunk was removed.

The hot set-up. A small cable. The line goes through the tank and will puncture if not being carefull to have flexibility. Wouldn't hurt to use some carb cleaner in the tube. I've had to deal w/leaky lines through the tank. No fix but new tank unless you have lots of $$$