Hello all,

Synopsis:
My XT660ZA (ABS, 2015) won't rev above 5.5k RPM, when the water temperature is above 107 �C (225 �F). When I try to rev it up, the "Engine" (yellow light) and "Temperature" (red light) flash momentarily, my throttle cuts off and my headlight dims for a split second. After dropping the RPMs, the throttle resumes.
Any ideas, what is the problem?



Full story:

I own a XT660ZA (ABS model, 2015), and I was doing 110+ kmh, on 4th gear, with the RPM up to 5500+, when suddenly the "CHECK ENGINE" and the "WATER TEMPERATURE" lights blinked for a second, my throttle was cut down momentarily but resumed after 1 sec. At first i though it might be the REV LIMITER and started asking around ( previous thread).

Since I also considered 5.5k RPM as a very low rev for Limiter, I had the bike checked on the YAMAHA authorized Dealer/Workshop where I bought it from.
We did the diagnostics test via the diagnostic port of the XTZ, but found no error code, except a "lean angle" problem (code 41), which was expected because I was had the sensor removed to rearrange some cable routing.
While trying to reenact the problem, we found out that the problem appeared only if the radiator water was above 107 �C (225 �F). When reving up from cold, everything worked fine.

This is the same temperature the radiator FAN kicks in. We disconnected the FAN, in case it was a FAN-problem, but the problem still occurred, thus eliminating the FAN as a cause of it. FAN: OK.

Then we checked the RECTIFIER, while running the engine, which outputted above 14.2V, so it was ok too. When the REV-cut-off was reproduced, the voltage stayed pretty much stable at ~14V, without any voltage drop. So RECTIFIER: OK.

We did a thorough inspection of the fuses, which found no fuses blown, so all these were OK: Main, Parking Light, Signaling System, Headlight, Ignition, Fuel Injection, Radiator Fan, ABS motor, ABS solenoid, ABS control unit. So FUSES: OK.

I am running the bike, pretty much stock, with only external spotlights and 12V power socket, and heated grips. All these are powered via a fused cable from the battery, which was disconnected when testing, so AUX POWER: OK.

IT HAS BEEN A STRENUOUS TEST and any help would be deeply appreciated!
Thank you!