Engine parts not included in the stock parts list (so-called
“aftermarket parts”) from third-party suppliers can be used
under the following conditions:
- The engine manufacturer is not involved in any way in the
design, production and/or sale of such parts.
- The parts are available to at least the same number of
riders as in Art. 2.3.6.2.7.c above.
- A price and lead-times list of such parts is submitted to
the Organiser for publishing, where the lead-times and
the prices are the same as the stock parts. An exception
is made for a Slipper Clutch (back-torque limiter clutch)
assembly that can be priced as much as double the cost
of the stock assembly, if the original is of the conventional
“non-slipper” type.
- The stock crankcase, cylinder, and cylinder head may not
be replaced by aftermarket items.
- Updates to the published parts list are permitted at any
time, always subject to approval by the Organiser.
- Any part that can be obtained by simple machining of a
stock part (e.g. polishing/porting/lightening), and generic
ancillaries not specialised to the specific engine design
(such as bolts, fasteners, filters) are not considered as
aftermarket parts, and so no conditions apply.