Only engine oils of up to W-30 viscosity can be energy conserving rated. Friction modifiers which are not wet clutch compatible are still found in some automotive W-40 and higher viscosity oils. Motorcycle specific oils are JASO MA certified for high friction applications, as recommended by Kawasaki.
From Castrol; "Note: The low friction characteristics of Castrol Edge 0W-40
make it unsuitable for most motorcycles that incorporate wet clutches in combined engine and transmission systems. Castrol’s prime recommendation for this application is Castrol R4 Superbike."
"Castrol does not recommend using automotive oils in motorcycles. In 1996, the American Petroleum Institute (API) upgraded the performance standards of automotive oil from SG to SJ (currently SM). This upgrade impacted the friction modifiers and zinc and phosphorus levels, to address the fuel economy, catalytic converter and pollution issues of passenger car owners. For motorcycles, the additional friction modifiers can affect wet clutch performance, and motorcycle engines appreciate a higher level of the anti-wear ingredients of zinc and phosphorus. We have formulated our line of Castrol Motorcycle oils to be API SG. This allows us to optimize the formula specifically for motorcycles without being constrained by the specification demands for passenger car engines, which our passenger car oil must meet. All Castrol Motorcycle oils have low volatility to reduce the effects of oil evaporation, and they can be up to 50% lower than many API SL/SJ passenger car engine oils. API SJ engine oils have a minimal shear stability requirement; therefore, some types may lose their viscosity more quickly when used in a motorcycle, due to the stresses of these bike engines."
There's also Shell's excellent Rotella T6 synthetic 5W-40 that's available for less as it's not JASO MA labeled, but still passes the tests. According to Richard Moore, Staff Engineer at Shell Global Solutions (US) Inc., Westhollow Technology Center, Houston, TX (800-231-6950):
"We recently ran the JASO MA friction test on Rotella T with Triple Protection 15W-40, Rotella T Synthetic 5W-40 (CI-4, discontinued) and our Rotella T6 Synthetic 5W-40 CJ-4. All three oils passed the wet clutch friction test. Rotella T Synthetic 5W-40 (CI-4) has more than 1.2% ash (JASO MA spec limit) so it can not be classified as JASO MA. However, Rotella T with Triple Protection 15W-40 and our Rotella T6 Synthetic 5W-40 CJ-4 do meet JASO MA."
Shell's Rotella T5 semi-synthetic is also a good choice.