70deg aux tank leak

Wiggy · Mar 14, 2011

Hi All,
I've had a 70deg aux tank fitted on my 390 Berg for a few months now and last weekend I noticed fuel running down the side of the bike from under the seat. The leak only occurs when the bike is filled to the brim which made me think that the tank vent was the culprit, but I've traced it to a red screw in cap under the ECU. The leak eventually stops after using a litre or so of fuel.
Pics of the aux tank on the 70degracing website have no red screw in cap where mine does, perhaps I have an early production tank ??????
Anyone else had a leak from a tank fitted with the red screw in cap and how did you fix it ?
Perhaps DaleEO has some words of wisdom for me ! :mrgreen:

70DEGREERACINGLLC · Mar 14, 2011

Wiggy said:
Hi All,
I've had a 70deg aux tank fitted on my 390 Berg for a few months now and last weekend I noticed fuel running down the side of the bike from under the seat. The leak only occurs when the bike is filled to the brim which made me think that the tank vent was the culprit, but I've traced it to a red screw in cap under the ECU. The leak eventually stops after using a litre or so of fuel.
Pics of the aux tank on the 70degracing website have no red screw in cap where mine does, perhaps I have an early production tank ??????
Anyone else had a leak from a tank fitted with the red screw in cap and how did you fix it ?
Perhaps DaleEO has some words of wisdom for me ! :mrgreen:

Hey Wiggy this is John Wiser, you actually have the latest version. That plug is installed by the roto molder, it was added to have another vent. You see a regular tank has a large fill hole to vent during the manufacturing process. Ours only has the hole where the light green cap is, this is the only real reason its there besides a possible burp or vent location during a quick fill. Anyhow you just need to remove the cap, clean the threads and make sure the cap and hole are dry then install with some teflon. Just tighten until it is just below flush. Let me know if this doesnt work. Thanks

Wiggy · Mar 15, 2011

Thanks for the reply John.
I've done as you suggested with yellow teflon tape, but after testing it with dishwashing detergent and gently blowing compressed air into the tank, I'm not confident about the integrity of the teflon tape as bubbles appeared around the cap. I'll fill the tank with fuel and see what happens then.

DaleEO · Mar 16, 2011

Hi Wiggy,

I have a question for you. When you installed your tank, did you remove the ball check valve in the stock gas cap as per the instructions?

And, are you running the stock inline check valve from the stock tank cap vent before it attaches to the frame?

Wiggy · Mar 17, 2011

Dale,
I still have the ball in the fuel tank filler cap. I left it in there as the instructions only recommended it's removal Aussie Bergs don't have an inline check valve from the stock tank cap vent before it attaches to the frame, where US bike do.

I'm not convinced it's a case of pressure buildup inside the tank forcing fuel out through the screw in cap. The subframe tank vent line is clear, so any pressure build up will be vented quite freely to atmosphere.

DaleEO · Mar 17, 2011

Wiggy said:
Dale,
I still have the ball in the fuel tank filler cap. I left it in there as the instructions only recommended it's removal Aussie Bergs don't have an inline check valve from the stock tank cap vent before it attaches to the frame, where US bike do.

I'm not convinced it's a case of pressure buildup inside the tank forcing fuel out through the screw in cap. The subframe tank vent line is clear, so any pressure build up will be vented quite freely to atmosphere.

So if it's recommended why didn't you do it?

jbrown15 · Mar 17, 2011

Dale,

Have you heard of any pressure build up problems when using the billet Husaberg gas cap?

campfire · Mar 17, 2011

Thinking about buying the 2011 fe570s, Is the 70 degree worth the money and do you think I can get 80-100 miles by adding this feature..Thanks

jbrown15 · Mar 17, 2011

I think it is very much worth it, of couse I have one so I might be a little bias! :mrgreen:
I have never gotten more then 65miles out of a tank of gas on either of my Berg's but some people have gotten that and more. If you were hoping to get 100miles out of a tank I would say the subframe tank is a must have for you IMO.

DaleEO · Mar 18, 2011

jbrown15 said:
Dale,

Have you heard of any pressure build up problems when using the billet Husaberg gas cap?

Hi J,

No pressure problems with the billet aluminum cap, it has a straight through hole with no check valve.

DaleEO · Mar 18, 2011

campfire said:
Thinking about buying the 2011 fe570s, Is the 70 degree worth the money and do you think I can get 80-100 miles by adding this feature..Thanks

The mileage you get depends greatly on your right wrist and the conditions you are riding in. I have gotten as much as 95 miles out of a stock tank, with fuel mileage in mind, and as low as 55 when riding in deep sand pulling ribbon, all stop and go every 50' or so.

And when riding nothing but single track in Idaho I was getting 42.5 mpg, which would equate to 94 miles with the stock tank, so with the extra gallon that the sub tank offers that would have given me a range of 136 miles.

With that being said I am confident I can get 90 miles on the gas, and well over 100 with my sub frame tank on. My partner John hooked some guys up with tanks that went to Colorado last year and they were making fuel stops at 125 miles with fuel left over. I have no idea what their riding was like, but still that's a big improvement.

You figure that you are increasing your fuel capacity by 50% with the subframe tank.

And of course I think it's worth it!

Wiggy · Mar 20, 2011

DaleEO said:
Wiggy said:

Dale,
I still have the ball in the fuel tank filler cap. I left it in there as the instructions only recommended it's removal Aussie Bergs don't have an inline check valve from the stock tank cap vent before it attaches to the frame, where US bike do.

I'm not convinced it's a case of pressure buildup inside the tank forcing fuel out through the screw in cap. The subframe tank vent line is clear, so any pressure build up will be vented quite freely to atmosphere.

Click to expand...

So if it's recommended why didn't you do it?

Dale,
The reason I didn't remove it at the time of fitting the tank was that I was a little paranoid about fuel running out the fuel cap if the bike was tipped on it side ! I ran the bike for a few months to see if having the ball in the fuel cap would be detrimental to the running of the bike.
I removed the ball over the weekend and the red screw in cap didn't leak, but I had also wrapped the threads of the cap with yellow teflon tape as John suggested, so it's hard say if removing the ball or the teflon was the actual fix. One thing that was obvious when filling the bike on the weekend was that I couldn't fill the aux tank to the 'brim", maybe when the screw in cap was leaking it performed a venting function which perhaps may point to the aux tank vent hose being restricted. Might have to check that the aux tank vent hose hasn't been "crushed" between the main tank and the frame !

DaleEO · Mar 20, 2011

Wiggy said:
DaleEO said:

Wiggy said:

Dale,
I still have the ball in the fuel tank filler cap. I left it in there as the instructions only recommended it's removal Aussie Bergs don't have an inline check valve from the stock tank cap vent before it attaches to the frame, where US bike do.

I'm not convinced it's a case of pressure buildup inside the tank forcing fuel out through the screw in cap. The subframe tank vent line is clear, so any pressure build up will be vented quite freely to atmosphere.

Click to expand...

So if it's recommended why didn't you do it?

Click to expand...

Dale,
The reason I didn't remove it at the time of fitting the tank was that I was a little paranoid about fuel running out the fuel cap if the bike was tipped on it side ! I ran the bike for a few months to see if having the ball in the fuel cap would be detrimental to the running of the bike.
I removed the ball over the weekend and the red screw in cap didn't leak, but I had also wrapped the threads of the cap with yellow teflon tape as John suggested, so it's hard say if removing the ball or the teflon was the actual fix. One thing that was obvious when filling the bike on the weekend was that I couldn't fill the aux tank to the 'brim", maybe when the screw in cap was leaking it performed a venting function which perhaps may point to the aux tank vent hose being restricted. Might have to check that the aux tank vent hose hasn't been "crushed" between the main tank and the frame !

Glad to hear that you got your leak fixed!!!

The main reason that the instructions say to remove the ball cap and only run a check valve after the T connection, E.G. between the tank vent and the frame after the sub tank T is to maintain equal pressure build up between the main tank and the subframe tank. If you don't set it up this way, if the fuel in the main tank boils, and the little ball check sticks shut in the cap, it will force the fuel in the main tank into the sub tank, and force fuel out the sub frame tank vent. That pressure wants to get out, and if you give it that path it will take it and you will loose fuel.

I have not run any kind of a vent blocking device on my bikes for years to keep pressure from building up inside the tank. And I know of several people who have had these vents clog causing vacuum lock.

So, if you are worried about loosing fuel in a tip over, just get one of those inline one way valves and put in line with the vent after the T fitting before it attaches to the frame.

Thanks for the report back!!

cmsprofessor · Mar 22, 2011

Hey Dale,
I love the sub-frame tank and the extended range it gives me. I was going to move it from my FE450 to a 570 and I noticed something I probably never would have seen otherwise. When I set it down against the wall the tail end was down and gas dripped from the holes where the fender top screws go through. Normally this would be much higher when mounted on the bike. I have never had any leaks and never smelled gas as I keep it in doors. My question is what product could I use to seal the holes in this area? I thought of heat welding it but it just seemed like a bad idea (maybe with an argon purge). Any advice would be appreciated as I want to use it on the new bike. Great product and I am very pleased I bought it.

70DEGREERACINGLLC · Mar 23, 2011

cmsprofessor said:
Hey Dale,
I love the sub-frame tank and the extended range it gives me. I was going to move it from my FE450 to a 570 and I noticed something I probably never would have seen otherwise. When I set it down against the wall the tail end was down and gas dripped from the holes where the fender top screws go through. Normally this would be much higher when mounted on the bike. I have never had any leaks and never smelled gas as I keep it in doors. My question is what product could I use to seal the holes in this area? I thought of heat welding it but it just seemed like a bad idea (maybe with an argon purge). Any advice would be appreciated as I want to use it on the new bike. Great product and I am very pleased I bought it.

I don't know of anything that really sticks to this material. You may try a little plastic welder and try to glaze it over but if it didn't leak on the bike I would say to try it. If it gives you trouble send me an email at [email protected] . Thanks

gooddoc · May 18, 2011

cmsprofessor said:
Hey Dale,
I love the sub-frame tank and the extended range it gives me. I was going to move it from my FE450 to a 570 and I noticed something I probably never would have seen otherwise. When I set it down against the wall the tail end was down and gas dripped from the holes where the fender top screws go through. Normally this would be much higher when mounted on the bike. I have never had any leaks and never smelled gas as I keep it in doors. My question is what product could I use to seal the holes in this area? I thought of heat welding it but it just seemed like a bad idea (maybe with an argon purge). Any advice would be appreciated as I want to use it on the new bike. Great product and I am very pleased I bought it.

I am seriously considering this tank but issues like this give me some pause. What is the reason for this leak. Is it a design issue or a manufacturing defect/mold issue?

DaleEO · May 18, 2011

We have had a small number of our tanks with leak issues. All of the leaks that we know of are caused during manufacturing, and 99% of the time they do not show up until the tank has been in use for a short time.

It is our policy to replace these tanks that have these issues. We are working with our manufacturer to reduce these infrequent problems to zero.

We have produced hundreds of these tanks and sent them all over the world with a very high degree satisfaction.

gooddoc · May 20, 2011

DaleEO said:
We have had a small number of our tanks with leak issues. All of the leaks that we know of are caused during manufacturing, and 99% of the time they do not show up until the tank has been in use for a short time.

It is our policy to replace these tanks that have these issues. We are working with our manufacturer to reduce these infrequent problems to zero.

We have produced hundreds of these tanks and sent them all over the world with a very high degree satisfaction.

Thank-you DaleEO, I appreciate your responsiveness to questions I have had (this is not the first

). I think you currently have the best solution for my extra fuel needs and you clearly stand behind your products.

Chief Lee Visceral · May 25, 2011

My tank is leaking out the red plug underneath the ECM as well when it is filled to the top and the bike is on the sidestand. I see some white residue in the leaked fuel so assuming this is from teflon tape. I will drain the fuel and see what I can do when time allows or this weekend and report back. My tank was installed by my dealer.

Harowerks · May 26, 2011

I fitted the 70 Degree fuel tank over a week ago and had a 10 klm ride on it with no leaks or problems.

Filled the tank tonight as usual and petrol has started coming out of the red plastic screw plug located under the electric box under the seat and from somewhere else around the quick connects or elsewhere between the tanks.

It is like the rear tank is being pressurised and forcing petrol into the rear tank from the front, or maybe it is just the height of the petrol in the front tank evening itself out.

I pulled the breather tube off and petrol was coming out of the tank tube in spurts so I connected another hose to it and it emptied around 4 litres of petrol by itself, though some of this may have been due to a venturi effect as when I pinched the tube to put the end into another petrol can it didn't run anymore.

Any one have any suggestions before I pull the whole thing apart, have to use the bike in the morning?

Just read the above suggestions and will try the teflon tape first and see how it goes.

70deg aux tank leak

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