I just checked out "Orma's KR Info" site at http://www.kr-2.aviation-mechanics.com/krinfo.htm, and it looks like Joe Beyer is flying a 1641cc VW engine in his 619 pound KR2, so there's proof that it can be done in a KR1, I'd say.
Speaking of Orma's site, he could use some more input there. Surely there are more than 19 flying KRs in the the world! Mark Langford, Harvest, AL see homebuilt airplane at http://www.N56ML.com email to N56ML "at" hiwaay.net
