December 18, 2015 — One of the many changes to the 2016 Rule Book for ROK Cup USA races is the addition of a new rule concerning water pump usage for the ROK GP engine. We have listened our customers, drivers, and teams, and have come up with a solution to alleviate the current water pump issue. We have implemented a new rule, which goes into effect January 1, 2016, that allows for the use of EITHER an internal or external water pump. The rule, which can be found in Section 18 of the 2016 Appendix for ROK GP states,
18. Water Pump
a. ONLY one water pump may be used, either the original internal one or an external one.
b. In case of use of external water pump, a special Vortex designed cap for the internal one MUST be used as per Homologation file.
c. In case of use of external water pump, all gears inside the crankcase MUST be keep it in the standard place and use except for part # W2005/2ROK.
d. External water pump MUST be located on the traverse tube of the chassis under the seat.
Vortex has conducted several tests and concluded that both options result in equal performance of the engine under all racing conditions. Depending on the applied maintenance of the engine, if the engine is removed and water drained after every usage, it is recommended to continue using the internal pump. If the engine is drained less regularly, then it is recommended to use the external water pump to prevent any issues.