This just in from AMA Pro Racing ...
2003 AMA U.S. Superbike Championship rules
Only approved motorcycles are permitted in AMA Superbike competition. AMA Pro Racing will accept homologation applications only from motorcycle manufacturers or their distributors.
Allowable engine displacements and basic homologation requirements:
551cc - 750cc four-stroke, four cylinders:
Engines with displacements originally within this range may have cylinder bore increased by a maximum of 2mm, with the resulting displacement not to exceed 800cc. Stroke must remain stock.
Homologation requirements will remain the same as current (2002) Superbike requirements, including street certification in an FIM member country and a minimum number of units imported into the US for sale.
551cc - 900cc four-stroke, three cylinders: 551cc - 1000cc four-stroke, twin cylinders:
Homologation requirements will remain the same as current (2002) Superbike requirements.
901cc - 1000cc four-stroke, three or more cylinders:
This is a new displacement category offered as an option beginning with the 2003 season.
Homologation requirements include street certification in the U.S. and a higher minimum number of imported units relative to current Superbike requirements.
Minimum weight for all Superbikes will be increased to 370 pounds from the current 355 pounds.
Other major technical regulations:
Except for the items previously noted, 750cc four cylinders, 900cc three cylinders and 1000cc twin cylinders will be subject to all current (2002) Superbike technical regulations for the 2003 season.
1000cc equipment with three or more cylinders will be subject to the following major technical regulations:
Frames must be stock except for the addition of strengthening gussets and the removal or relocation of accessory brackets (same as current rules).
Aftermarket forks, shocks and swingarms will be permitted. Forks/shocks will be subject to claiming rules (same as current rules).
Aftermarket wheels (except carbon composite) will be permitted. Rear wheel maximum width is 6.25" (same as current rules).
Aftermarket brakes (except carbon composite) will be permitted (same as current rules).
Aftermarket fairings and body work will be permitted (same as current rules).
Cylinder heads may be ported and machined, but altering of valve angles will not be permitted.
Aftermarket valves, springs, retainers and other valve-train components will be permitted. Valves must be stock size and same basic material as original equipment.
Aftermarket camshafts will be permitted, but cam lift and resulting valve lift must be no greater than stock.
Stock cylinders and cases must be retained. Machining will be permitted (same as current rules).
Aftermarket pistons, rings, pins and connecting rods will be permitted (same as current rules).
Stock crankshaft must be retained. The only allowable modifications are balancing, polishing of bearing surfaces and attachment of accessory drives.
Homologated transmission gear sets (one optional set of ratios per approved model) will be permitted. Optional sets will be price-controlled and must be available to any legitimate AMA Superbike competitor.
Aftermarket, stock-type (wet type cannot be changed to dry type) clutches with back-torque limiting characteristics will be permitted.
Homologated fuel-injection throttle-body assemblies (one optional type per approved model) and aftermarket air boxes will be permitted. Modifications to throttle bodies will not be permitted. Optional throttle bodies will be price-controlled and must be available to any legitimate AMA Superbike competitor.
Aftermarket ignition systems will be permitted (same as current rules).
Charging systems and starters will not be required (same as current rules).
Aftermarket exhaust systems will be permitted (same as current rules).