Fuel tank cap / reserve?

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Jul 10, 2004
I recently "converted" my Interstate to a cafe style machine, with a smallish fibreglass fuel tank. I plan to swap the new high quality taps from my I-state tank but have not done so yet. I know that neither of these new petcocks has a "riser", but I have not removed and examined the petcocks in the new small cafe tank. Initially I was using the left hand petcock for my normal running, and the r/h for reserve. Twice I ran out and switched and had only a very short reserve (maybe 2 miles?). Yesterday I took this bike out to the British and Euro Motorcycle Day in MD, about 300 miles r/t. I am now using the r/h tap as my main feed, leaving the l/h for reserve.

I was careful with each (of many) fillups, the most I was able to fill was about 2.6 gal. And on this ride I got about 47 mpg, not bad at all? On the last tankful on the way home I hit reserve at about 85 miles and had to switch over. Fortunately I found a station within about 5 miles, holding my breath the entire way there.

This is really taking some getting used to. My BMW LT has a 6.5 gal main tank, and I have a 3-gal aux fuel cell; need less to say I can go 400+ miles between fillups!

Comments are welcome. Stuart Ostroff

On a typical roadster gas tank, there is no communication between the “saddles” on each side of the tank. So for this reason, Debby and other forum members report that they have installed two reserve petcocks, the ones without the riser.

They turn on only one petcock at a time and when that side of the tank runs dry, they turn on the opposite petcock. The amount of reserve is a function of the volume in one of the “saddles”. I’m not sure what this volume is but I’m quite sure it will provide more than the 2-5 miles your current reserve system provides. Your gas tank may be configured differently but it’s worth investigating.

I have the fibreglass roadster tank which holds 2.5 gals or so. On my last club ride I got 55 mpg (not bad for "worn out" amals!) and was able to go over 100 miles without hitting reserve.

I haven't actually put the reserve to the test yet so don't know how far I would get. Probably not very far. My basic strategy is to pull into the next gas station I find if I do hit reserve. I ran the old 850 dry once (it had the normal reserve tap) after something like 20 miles IIRC.

And I guess this is a perfect opportunity to say:
YMMV (literally!) :D

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