HPN 43l tank - a silly question

[topher]

Perhaps a silly question, but having fitted my new tank (having read all the advice resulting from a previous thread that I started) I noticed that the lowest point of the tank is considerably lower than the fuel taps.

Am I correct in assuming that this is to keep the centre of gravity low and that the petrol in these lower parts will never be used? (another expanation could also be that my somewhat basic knowledge of the physics relating to the behaviour of petrol in tanks is misleading me in some way).

If the petrol in this part of the tank isn't ever used (if that is the case) is it included in the 43l capacity that HPN quote for the tank.

Any enlightening replies would be very welcome!

Cheers

Chris

 

[brassmonkey001]

You'll need to learn to wheelie if you want that last pint!

 

[judge]

43 litres is the actual capacity not the real usable capacity, much like every other tank except as you point out the lobes are below the petcocks and its fuel you never use before running dry.

The advantage is it carries fuel very low and helps with COG which is nice given the extra weight you're carrying (but cannot use). I have a 35 litre PD tank have run it dry on a couple of occasions and never got 35 litres of fuel in. But is has a considerably better usable fuel capacity over the Touratech/HPN/Acerbis tank (and far cheaper to buy). I'd have all the capacity I'd want with my PD tank and a 5 litre can strapped on for good measure. Price of can £5, no brainer.

 

[Spout]

My missus always leaves half inch of tea in her cup. Doesn't matter how full it's filled, or what size cup/mug she uses.

And her centre of gravity is getting lower.

Hope this helps.

 

[(RIP) pastyman]

The logic of this is that if you are that low then it is useful if you have to travel uphill to the next petrol station. If the next station is downhill then you could freewheel to it and wouldnt need the extra bit left.
Bit of a bugger if you are on the level though.

On a serious note though, As it sits on the bobbins fastened to the frame, make sure you have not set them too low. The tank should not sit on the top frame. The bottoms are below the taps but I would not call it "considerably lower".

 

[BamBam]

Perhaps a silly question, but having fitted my new tank (having read all the advice resulting from a previous thread that I started) I noticed that the lowest point of the tank is considerably lower than the fuel taps.

Am I correct in assuming that this is to keep the centre of gravity low and that the petrol in these lower parts will never be used? (another expanation could also be that my somewhat basic knowledge of the physics relating to the behaviour of petrol in tanks is misleading me in some way).

If the petrol in this part of the tank isn't ever used (if that is the case) is it included in the 43l capacity that HPN quote for the tank.

Any enlightening replies would be very welcome!

Cheers

Chris

Hi HPN/Acerbis is designed for a HPN race preped bikes with longer forks, then it would sit level have the same problem myself.
Cain

 

[judge]

My missus always leaves half inch of tea in her cup. Doesn't matter how full it's filled, or what size cup/mug she uses.

And her centre of gravity is getting lower.

Hope this helps.

It won't help you if she sees this

 

[topher]

Thanks gentlemen! I feel suitably enlightend.

I plan to fill the tank this weekend (in Austria where fuel is much cheaper) and run it dry of the next week (time permitting). When I have done this I'll post the actual, usable capacity of the tank in this thread.

Cheers

Chris

 

[(RIP) maverick]

Yes it keeps the COG very low and help you get to the ground much easier in the sand

Unfortenately I never managed to ride my bike until all the fuel was finished so can't comment on how much it would take to fill up again. What I can tell you it certainly performs very well on most terrains offroad except in deep sand where you need to keep your wits about

 

[topher]

A bit of feedback for anyone who is interested. I rode exactly 600km before the reserve kicked in, and then a further 87km before the tank was empty. In total the tank then took just over 42l to fill so the "unusable" capacity of the tank is less than 1l, which doesn't seem too bad to me.

Thanks again for the replies to my enquiry!

Chris

 

[BegesRus]

Surely that's a good thing - if you don't use the pertol it's cheaper to run the bike - yeah!