Mike, And, as long as you mentioned it, FAA regulations do not actually require any kind of instruments - flight or engine - for experimental category airplanes. However, builders would throw safety to the wind if they didn't. You would have a very difficult time finding an FAA (DAR or whomever) that would issue a Special Airworthiness Certificate to an experimental aircraft not having at least the basic instruments. For example, a compass is not required by the regs, but a DAR might require one before he issued a certificate. In such case, a compass from the aviation aisle of Walmart might get you by.
Ed "Just a clarification for those suggesting that KR are not "certified" aircraft - KR aircraft ARE "certified" aircraft, just as Pipers, Cessnas, etc. are." Thanks for pointing that out Ed. I've been making the mistake of referring to the "other" aircraft as certifieds in various conversations, thus implying that Experimentals are not. It usually comes up in relation to conversations about what avionics & instruments can be installed . . . or not. Mike