690 Rally Raid Evo 2 tank problems

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Werner747

Pack Dog
Joined
Sep 13, 2006
Messages
328
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Location
Pretoria
Bike
KTM 690 Adventure
Hi,

I installed the Evo 2 Tanks earlier this year. I followed instructions meticulously, and did everything to the letter.
I have also experience the tank overflowing / bubbling / not feeding to rear tank problems, as some others have experienced.

On a previous trip to Botswana, after a very rough sand section, at the hottest time of the day, when I stopped, I noticed both front evo 2 tanks were full, and streaming fuel out of the overflow pipes on the caps. So much that I lost about a litre. The only explanation that I have for that occurrence, that makes sense to me, is that the pressure built up, from all the shaking, and heat, The main tanks vent must have been blocked somehow, and the pressure pushed fuel from the main tank to the front evo tanks.

The past weekend, I also had the problem where the front tanks would not drain to the main tank, so "I ran out of fuel" about ten times. I needed to stop, open evo tank cap, and blow into the tank, to get fuel to transfer.

I have read the threads on ADVrider relating to this.
I have checked that my vent tubes are clear and does not get pinched by the seat when weight is applied.
I have checked the tubes from the evo tanks to the main tank, and nothing gets pinched.

So, for extra piece of mind, I am now replacing the standard rubber tubing, with steel braided fuel line, and then also, I don't think the standard main tank vent, as in this picture:

provides enough venting, as it also has a one way valve in there. So plan is to drill out that vent, and remove one way valve.

But, I have been thinking about not connecting the evo tanks to the main tank, via the adapter at the bottom of the main tank, but, rather connect it to the main tank vent, once I have drilled it out.
That way, a vacuum is formed, and the front evo tanks gets sucked dry before any fuel is used from the main tank, that will suit me fine.
I have, on my previous X-challenge, run my fuel system that way, and had no problems in 10 000 + KM.

Any reason that anyone can provide, why this is a bad idea? ???

Any advice is welcome...
 
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