Here is the link to the FTC site that explains the A Businessperson's Guide to Federal Warranty Law. This is the law that regulates written warranties in consumer products in the US. http://www.ftc.gov/bcp/edu/pubs/busi...#Magnuson-Moss
A warranty that requires service from an authorized dealer would have a Tie in Sales provision. This is no allowed under Federal law. However, Kawasaki warranty can state that service needs to be performed by a qualified technician. The term "qualified technician" can be debatable in court. Kawasaki does offer clear technical specifications about what needs to be done when, and have specific recommendations about who should do it. I understand that anyone that can read and follow a set of technical specifications is qualified to do standard maintenance items.
Below is what the law states about tie in sales provisions.
Tie-In Sales" Provisions
Generally, tie-in sales provisions are not allowed. Such a provision would require a purchaser of the warranted product to buy an item or service from a particular company to use with the warranted product in order to be eligible to receive a remedy under the warranty. The following are examples of prohibited tie-in sales provisions.
In order to keep your new Plenum Brand Vacuum Cleaner warranty in effect, you must use genuine Plenum Brand Filter Bags. Failure to have scheduled maintenance performed, at your expense, by the Great American Maintenance Company, Inc., voids this warranty.
While you cannot use a tie-in sales provision, your warranty need not cover use of replacement parts, repairs, or maintenance that is inappropriate for your product. The following is an example of a permissible provision that excludes coverage of such things.
While necessary maintenance or repairs on your AudioMundo Stereo System can be performed by any company, we recommend that you use only authorized AudioMundo dealers. Improper or incorrectly performed maintenance or repair voids this warranty.
Although tie-in sales provisions generally are not allowed, you can include such a provision in your warranty if you can demonstrate to the satisfaction of the FTC that your product will not work properly without a specified item or service. If you believe that this is the case, you should contact the warranty staff of the FTC's Bureau of Consumer Protection for information on how to apply for a waiver of the tie-in sales prohibition.