R100/7 Reserve?

[bmwhacker]

Originally Posted by Bigger Al

It's worth it, though.

+1000

I replaced my petcocks recently with the 90 degree ones and they also hit reserve at 4.8 gallons.

[boxerboy81]

You guys are getting different numbers to me.

My 11/1981 R100RS with Germa taps hit reserve today at 335ks or about 211 miles. This was 80% 100-120kph at reasonably steady hwy throttle, the rest commuting. I'm very happy with that fuel consumption.

I rode about 18ks home after switching to the right reserve,

I drained the unused left reserve of 1.9 litres. If the right side is identical, then reserve on this tank is at 20.2litres (/3.78 = 5.4USgall)

My previous BM's all had Karcoma taps and I remember doing a calc years ago that the reserve was 1.5 litres per side, but my current bike has Germa taps. Might there be a difference in the reserve tube lengths? I guess any previous owner may have fiddled with the lengths?

I have just bought some angled Karcoma's to put on this tank. When I get them in a few weeks, I'll do a similar exercise and compare the pipe lengths and the reserve numbers.

Are my conversions to US gallons right?

[bpeckm]

Reserve depends not on the brand of tap, but on the shape of the tank and how long each straw is.... the longer the main straw, the sooner you will run it out of that fuel, and go to your reserve.

Imagine two straws sticking up from the bottom of a glass: it will draw gas out of the tall (main) until that straw is level with the water. Then you can draw out of the short straw (reserve) until you get to the top of that one... that is when you are empty.... BUT if you can shake the bike around and get all of the residual gas over to ONE side, you will a little bit left... use that, and you are indeed e.m.p.t.y. .....