[Jumbo Jet]

The best cleaner I have come across for this is S100 Total Cycle Wash. You can find it online or at any Harley Davidson dealer. The Harley dealer usually has a nice size 1.32 gallon bottle for around $45..... that will last the weekend warrior a small lifetime. They also have 33 oz. bottles. For wheel wells and engine bays I dilute it 5:1. Its non-acidic so it wont stain if you let it sit too long. Works amazing for bugs on the front too. One of the best all around cleaners I've used.

http://www.autogeek.net/s1geltocycl.html

Its labeled as S100 only to the biker crowd...... for car detailers its labeled as P21S, but they are both the same products. S100 is a little less expensive too.