The Aprilia rider came into Sunday’s 25-lap grand prix in Portugal as one of the favourites for the victory, having won the sprint on Saturday.
Vinales was a factor in the victory battle from the off, breaking away from the rest of the field between eventual winner Jorge Martin and Enea Bastianini behind him in third.
But from the early stages, Vinales started to suffer from a gear selection issue between fifth and sixth gear.
As he accelerated onto the pit straight to start the last lap, his Aprilia went into neutral as he tried to change to sixth gear, which led to his sudden slowing down while running in second.
Vinales then says the bike suddenly engaging second gear when he touched the accelerator after running off at Turn 1 led to him crashing out.
“After the uphill on the finish line, I tried to put sixth but it didn’t go in,” he explained when asked what happened when he slowed onto the last lap.
“So, the bike goes into neutral and I hit the limiter. I just put out the leg to [warn] Bastianini to understand that I had some problems [and] to go away.
“I tried to put sixth, it didn’t go in, I go back to second and when I touched the gas it went in immediately and I high-sided.”
Source: Autosport