I have an XR 650R, stock tank, uncorked, rejetted, that rips, but runs out into reserve at 42 miles or so. I'm talking about trail riding, or GP/cross country stuff. Is this about normal? What is the opinion on the bigger tanks (Clark or IMS?) Are they bulky? Top heavy when full? worth adding? I'd like a little more range for some 50 mile rides we are planning this summer.