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Chilehead
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Discussion Starter #1
I recently have had some problems of the rear tire on my SS1000 spinning on certain occaisions. After thinking about the problem, it was clear that it occurred when the tank was almost full, and the bike was accelerating hard, usually uphill.

I then moved the tank-vent tube from it's normall position (exiting in front of the rear tire at the bottom of the fairing), and re-routed it to exit at the RH passenger mount. No problem since, and there is evidence of fuel on the RH muffler and rear hugger, thus confirming my suspicions. Also, a friend of mine with an MTS told me that he had had the same problem.

So, has anyone else had this problem, and if so what have you done as a permanent solution?

Thanks,

Tom
 

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so, what you are saying is that the fuel comes up into the lip of the fuel cap and ends up going into the drain hole?

Sounds to me like the bike is filled too much with gas...

Do you have the little rubber piece that connects to the bottom of the fuel lid and goes into the tank a few inches?
 

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you could route it to a small catch tank. Takes a lot of fuel to make a tire spin (as opposed to oil), it must be much more than a couple drops.
 

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Chilehead
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Discussion Starter #4
JDuc said:
so, what you are saying is that the fuel comes up into the lip of the fuel cap and ends up going into the drain hole?
Yes.

JDuc said:
Do you have the little rubber piece that connects to the bottom of the fuel lid and goes into the tank a few inches?
I don't have an OEM tank/fuel cap.

Interestingly, I've only noticed the problem since installing the BST wheels!

My ST2 will also piss some gas under acceleration with a mostly full tank, but I've never had a problem with the rear wheel losing traction because of it.

Tom
 

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If you don't have the OEM tank/cap, my suggestion is look at that first. Fuel is obviously leaving the tank at some point, and getting to find that point starts at the tank. Is the tank breather valve working? Is the cap sitting properly? Does the cap seal? Are the fuel lines connected properly at the base of the tank?

You also mention you noticed this when the wheels were changed. (It ALWAYS works that way doesn't it? :) ) Was any other work done at the same time? Did whoever do that perhaps remove the fuel lines or something there?
 

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Chilehead
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Discussion Starter #6
ward said:
If you don't have the OEM tank/cap, my suggestion is look at that first. Fuel is obviously leaving the tank at some point, and getting to find that point starts at the tank. Is the tank breather valve working? Is the cap sitting properly? Does the cap seal? Are the fuel lines connected properly at the base of the tank?

You also mention you noticed this when the wheels were changed. (It ALWAYS works that way doesn't it? :) ) Was any other work done at the same time? Did whoever do that perhaps remove the fuel lines or something there?
There is no breather 'valve'. In Europe, it's just a tube. And that is where fuel is exiting.

My question is not how to stop fuel from exiting the breather, but where to route it so that it doesn't get all over the tire. I suppose I could re-route it further forwar, like on my ST2.

Tom
 

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Why not re-route it back to the tank?? You might pick up a one way vacuum valve and set that into your fuel return line.

Just a thought but if you don't like it... read my tag line!!! hahaha


Mal
 

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Chilehead
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Discussion Starter #8
mals900ss said:
Why not re-route it back to the tank??
Because the purpose of a breather is to let the tank breathe, and re-routing it to the tank will defeat that.

Tom
 

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Don't mean to sound fixated, but I am pretty certain all new ducs have the breather valve fitted on the front vent pipe. (My Euro spec 749 did). It restricts the airflow / pressure direction into and out of the tank. Normally if this is defective it builds pressure in the tank, and the usual symptom is bad running, plus the huge hishing sound when you open the cap. BUT perhaps (?) in your case this is somehow pushing the fuel over onto the overflow pipe?

IMHO the location of the overflow drain is not the problem, but that fuel keeps coming out of it. The only time I've ever seen fuel drip out the drain on any of my bikes is when I've overfilled the bike, and that's usually at the gas station. It's not something you expect normally - especially enough to unsettle the back tyre. I'd be more concerned about the fact there's gas pissing out, not where it's pissing out to!! :0
 

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Chilehead
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Discussion Starter #10
ward said:
Don't mean to sound fixated, but I am pretty certain all new ducs have the breather valve fitted on the front vent pipe. (My Euro spec 749 did). It restricts the airflow / pressure direction into and out of the tank.
Not the SS1000



Tom
 

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I learnt something today! Thanks Tom.

I'm going to scratch my head on this one for a while. Still interested in stopping fuel coming out, not where it's going to...
 

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Tom - one of those pipes out the bottom of the tank is the breather, the other goes into the emissions system doesn't it? Maybe one of these is kinked, so stopping the tank pressure from stabilising?
 

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I saw a guy at the track this weekend who just routed all the overflow hoses to a small plastic bottle he zip tied to the frame. Wasn't fancy but looked like it would solve your problem.
 

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Hmmm... to a greater or lesser degree they all have some. Doubt if Euro specs are as strict as US, but there are some nods in that direction. All by the by though... my point is that there has to be some method of the tank being able to equalise the changes in pressure brought about by the reduction in fuel/air space and the action of the fuel pump.

Of the two hoses leaving the bottom of your tank, one is an overflow, and the other would be a means whereby air can get back in to the tank (If air can't replace the fuel that's drawing out in normal use, you create a vacuum in there).

My suggestion is that this breather tube is kinked/blocked/bent and that is not allowing the pressure adjustment to occur 'naturally', which could lead to fuel being pushed out the overflow pipe (and thence to your back wheel).
 
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