Boxerworks.com

What is the total capacity of your tank? 24 litres is the stated capacity in the specs, but even from bone dry, that's a difficult task to get 24litres in there. The recess in the filler hole probably hinders that.

Do you know your reserve capacity, l & r? Karcoma verses Germa taps? Anyone actually done a measurement?

My R100RS, 11/1981 build has the S style 24 litre tank with screw in cap. Divide 24 x 3.78 (litres per USgall) and that's 6.35US gall.

I've always calculated my tanks to be 24l, with 3 litre split reserve, ie 1.5l per side. I did this calc way back in the '80's on another R100RS, so that I knew how far I had to go before empty.

My previous BM's all had Karcoma taps, but my current bike has Germa taps. Might there be a difference in the reserve tube lengths? I have just drained the left side, after hitting reserve and using the right tap at reserve. I drained 1.9 litres. If the right side is identical, then reserve on this tank is at 20.2litres (5.4USgall) edit:Reserve on this tank is reached after 20.2 litres of use. That makes more sense.

I have bought some of the angled Karcoma's, and when I get them, I'll compare the two inner tube lengths...and report back.

'78 R100s.
I usually measure my tank in bladder-capacity, or butt-numbness.
(they come first, still got gas in the tank.)

One can change the reserve capacity by adding to, or cutting off some of the tube.

The original R90S tank with a flip up cap you could fill right to the brim, but the screw in caps allways had a bit of air in the top. I don't remeber ever getting more than about 22 liters in my /7 tank.

That was a long time ago, and there are many other thing I don't remeber.

What was the question again?

SteveD wrote:I have just drained the left side, after hitting reserve and using the right tap at reserve. I drained 1.9 litres. If the right side is identical, then reserve on this tank is at 20.2litres (5.4USgall)

Huh?

huh?

Reserve on this tank is reached after 20.2 litres of use. That makes more sense.

Garnet wrote:The original R90S tank with a flip up cap you could fill right to the brim, but the screw in caps allways had a bit of air in the top. I don't remeber ever getting more than about 22 liters in my /7 tank.

You're right there re: the screw in caps. They don't seem to take as much despite the same specs of 24litres from 76-84.
I'm wanting to see if everyone has the same reserve volume. It seems from my reading that the USA has a bigger reserve.

I realise this can be adjusted by trimming the lengths of the pipes, but I'm more interested in what my reserve volume is (sorted @ 3.8litres) and how it compares to others.

My 77/7 had at least 4L left when I went on reserve. That was with the old petcocks that gas lines pointed down.

As Duane pointed out you can easily adjust the reserve by changing the "straws" on the petcocks.

On my /7 (6.3 gal), I consistently get around 4.6 gallons when I first go on reserve. I usually then run only on the left petcock reserve. On rare occasion, I have had to go to the right petcock reserve. From those instances, I have determined that nominally I have about 0.75 gallons on the left saddle of the tank. I would suspect that I also have 0.75 gallons of reserve in the right saddle of the tank. The sum would be 6.1 gallons. This would leave about 0.2 gallons below the reserve straws. Seems to be reasonable.

Kurt in S.A.

Garnet wrote: As Duane pointed out you can easily adjust the reserve by changing the "straws" on the petcocks.

Yes, but I'm asking what others experience, preferably with known oem size "straws". It seems they're different here in Oz. Mine reaches reserve at 5.3 US gallons. Others In the USA report 4.5-4.6 US gallons.
I don't want to adjust them, just know what I should have. Once I know that, then I can calculate distance left.

I also like to know if there is a known difference b/w Germa and Karcoma, as they come oem, not with trimmed "straws".
To further that, does anyone know what the oem measured straw lengths are?