Yamaha’s MotoGP engine allocation is running thin.

The factory Yamaha team insists it has no concerns over a shortage of new engines for the remainder of the 2013 MotoGP season.

World champion Jorge Lorenzo and teammate Valentino Rossi are already on engines four of the allocated five allowed for the year.

However according to team director Massimo Merregalli, Yamaha is not yet worried about its rapid use of its engine allowance.

“We have had one problem with each rider, so for safety reasons our engineers decided to seal the fourth engine and keep the second one as a spare,” Merregalli said.

“Just because they first of all have to understand what has happened and for us to be able to solve it as soon as possible.”

With the second engines of both Lorenzo and Rossi having suffered issues, the pair will now be toggling between their first, third and fourth units before Yamaha elects to use the fifth for the first time.

“Anyway, the durability is pretty good and our engineers are pretty sure that as long as nothing happens such as an accident, like at Assen last year, we should finish the championship with five engines,” he added.

Repsol Honda Team duo Dani Pedrosa and Marc Marquez are still on their second engines of the campaign.