I found some interesting bits of the Iron Butt riders. Not many Harleys.
https://www.ironbutt.org/ibrfacts.htm
Highest number of miles ridden during a single Iron Butt Rally:
Year Place Rider Home Miles Motorcycle
2011 3 Jim Frens NH 14,185 Honda Gold Wing ('10)
2021 1 Mike Brooke CA 13,906 Suzuki Hayabusa ('08)
2011 5 Curt Gran WI 13,857 Honda ST1300 ('07)
2021 5 James Owen PA 13,617 BMW R1200RT ('18)
2011 1 Peter Behm MN 13,544 Yamaha FJR 1300 ('04)
2021 6 Wendy Crockett SD 13,510 Yamaha FJR1300 ('05)
2021 10 Ken Aman NY 13,385 Yamaha FJR1300 ('16)
2013 30 Bob Lilley PA 13,380 BMW R1200GS ('11)
2001 82 George Barnes CO 13,357 BMW K1100LT ('00)
2005 4 Mark Kiecker CA 13,354 Honda VFR800 ('00)
1999 1 George Barnes CO 13,346 BMW K1100LT ('95)
2019 22 Peter Green NM 13,314 Triumph Trophy ('13)
2005 1 Shane Smith MS 13,277 Honda ST1300 ('03)
2005 6 Marty Leir MN 13,256 BMW R1150GS ('00)
2011 9 Brian Johnson MN 13,198 BMW K1200LT ('03)
2011 4 Roger Sinclair VA 13,195 BMW R1150 GS ADV ('02)
2021 2 Ben Ernst TX 13,184 BMW R1250GSA ('20)
2011 2 Eric Jewell CA 13,162 Honda ST 1300 ('07)
2017 2 Bob Lilley PA 13,124 BMW R1200GSA ('16)
2021 4 Steve Giffin PA 13,114 Yamaha FJR1300 ('05)
2011 6 Kirsten Talken-Spaulding VA 13,110 BMW R1200RT ('09)
2011 7 Tom Loftus WA 13,092 Honda ST1300 ('07)
2017 7 Wendy Crockett CA 13,083 Yamaha FJR1300 ('05)
2019 1 Wendy Crockett SD 12,999 Yamaha FJR1300 ('05)
2013 2 Josh Mountain CA 12,963 Yamaha FJR1300A ('06)
2011 10 Tom Sperry CA 12,955 Honda Gold Wing ('08)
2005 38 George Barnes CO 12,950 BMW K1200LT ('01)
2019 7 James Owen PA 12,936 BMW R1200RT ('18)
2015 25 Will Barclay FL 12,900 Harley-Davidson Ultra Classic ('14)
2017 1 Jim Owen PA 12,885 BMW R1200RT ('15)
2019 38 Ken Aman NY 12,842 Yamaha FJR1300 ('16)
2011 8 Dick Peek UT 12,782 Yamaha FJR1300 ('06)
1999 9 Shane Smith MS 12,780 Honda ST1100 ('98)
1987 1 Barry Norman OH 12,773 Yamaha Venture ('83)
2005 11 Jim Phillips GA 12,731 Honda GL1800 ('03)
2019 9 Kevin Gardner GA 12,711 Honda Goldwing ('08)
2009 1 Jim Owen PA 12,706 BMW R1200RT ('07)
2009 25 Chuck Gittner FL 12,669 BMW K1200LT ('05)
2007 11 Jim Frens NH 12,658 Honda GL1800 ('04)
2009 18 Brian Jack WA 12,629 BMW R1150GS ('05)
1999 2 Rick Morrison WA 12,625 BMW K1100LT
2005 7 John Ryan NJ 12,573 BMW K75 ('95)
2005 70 Brett Donahue MN 12,525 Harley-Davidson Sportster ('04)
2021 12 Kirsten Talken-Spaulding VA 12,524 BMW R1200RT ('15)
2009 13 Matt Watkins WA 12,502 Yamaha FJR1300 ('05)
2005 32 Geoffrey Greene TN 12,494 BMW R1100RS ('94)
2005 17 Terry Pipes LA 12,483 Honda GL1800 ('02)
2011 14 Corey Nuehring IA 12,482 Yamaha FJR 1300 ('08)
2005 13 Allen Dye TX 12,463 BMW R1150RT ('04)
2007 1 Marty Leir MN 12,460 BMW R1200GSA ('06)
1993 1 Steve Attwood GBR 12,458 Moto Guzzi MK III LeMans ('83)
2003 2 Mark Kiecker IL 12,418 Honda VFR 800 ('00)
2005 34 Morris Kruemcke TX 12,413 Honda GL1800 ('01)
2003 3 Marty Leir MN 12,411 BMW R1150GS ('00)
2021 8 Steve Gallant MA 12,405 Honda ST1300 ('12)
1999 6 Gary Eagan UT 12,405 BMW K1100LT
2021 3 Mike Heitkamp MN 12,395 BMW R1200GSA ('15)
2019 3 Steve Gallant MA 12,370 Honda ST1300 ('12)
2009 12 Roger Sinclair VA 12,365 Kawasaki Concours 14 ('08)
2019 4 Craig Brooks CO 12,352 BMW R1200GS ('11)
2021 9 Bob Lilley PA 12,341 BMW R1200GSA ('16)
2011 15 Wendy Crockett CA 12,336 Yamaha FJR 1300 ('05)
2017 5 Erik Lipps CA 12,307 Yamaha FJR1300 ('12)
1999 7 Peter Hoogeveen ON 12,299 Honda CBRXX
2005 2 Chris Sakala MD 12,279 BMW R1150GS-ADV ('02)
2015 27 Greg Rice FL 12,278 Honda Gold Wing ('12)
2021 7 Eric Bray VA 12,275 BMW R1200GSA ('15)
2009 8 Bob Lilley PA 12,268 BMW K1200LT ('03)
1995 1 Gary Eagan UT 12,266 BMW K1100LT ('95)
2001 1 Bob Hall OH 12,247 BMW R1100RT
2009 4 Chris Sakala MD 12,238 BMW R1200RT ('08)
1999 5 Eric Jewell CA 12,237 BMW R1100RT
2005 16 Tim Conway MN 12,224 BMW R1150GS ('00)
2001 2 Shane Smith MS 12,219 Honda ST1100 ('98)
2005 26 Harry Kaplan NY 12,193 Yamaha FJR1300 ('05)
1987 2 Fran Crane CA 12,166 BMW K100 ('85)
2009 2 Jeff Earls OR 12,153 BMW K1200GT ('07)
2005 31 John Ferber ON 12,142 Yamaha FJR1300 ('04)
2009 21 Andy Kirby MA 12,135 Honda ST1300 ('04)
2011 23 Tim Masterson TX 12,096 BMW R1200 GS ADV ('08)
2009 3 Eric Jewell CA 12,090 Honda ST1300 ('07)
1999 3 Manny Sameiro NJ 12,086 Honda Gold Wing
1999 3 Harold Brooks VA 12,083 Honda Gold Wing
2005 8 Eric Jewell CA 12,081 BMW R1150RT ('02)
2005 14 Tom Loftus 12,079 Honda GL1800 ('05)
2005 10 Peter Hoogeveen ON 12,065 Yamaha FJR1300 ('05)
2011 12 John Harrison AL 12,034 Honda ST1300 ('07)
2021 24 Chris Hopper TX 12,033 Harley-Davidson Road Glide ('20)
1995 6 Ron Ayres TX 12,007 BMW K1100LT ('95)
2009 32 Kevin Lechner GA 12,001 Honda ST1300 ('07)