I use Simple Green full strength, let it sit a few minutes and spray. If the bike is really dirty, then I'll wipe the painted surfaces, wheels and other exposed bits with a rag soaked in Simple Green followed by a rinse with the pressure washer.
2008 Versys, 2008 ZX6R, 2006 EX500, 2002 KLR650
2010 KTM 300XCW, 2007 KTM 200XC, 2006 KTM 200 XC,
2004 CRF250X, 2002 CRF150