Jay Marmont jokes he won't mind racing when he's got grey hair, but knows his time will be up when he's not that guy always challenging at the pointy end.

So after a disappointing season attempting to defend his supercross crown, the rejuvenated Wollongong ace confirmed he will return to Yamaha this year with every intention of wresting back a national title.

"They've made a lot of changes to the new bike [YZ450F] and it works really well," the 30-year-old said after officially ending a difficult couple of years with Kawasaki.

"It suits my style a lot and after hopping off the Kawasaki - I never really disliked the bike but I never really gelled with it at motocross," he said.

"The Yamaha power seems to be [greater] and it works a lot better for me on track."

Marmont's first stint with Yamaha yielded four straight national motocross titles (2008-11), but he could only generate the one supercross title (2012) with Kawasaki.

Yamaha team owner Craig Dack opened negotiations with Marmont shortly after the end of last season and swiftly sealed the champion's return.

"I wanted to be on a team that I knew was strong and one where I could win a championship with," Marmont said.

"I've always done well in races and won a lot of championships.

"When I stop being at the front of the field I'll be too hard on myself and that's when I'll stop enjoying racing.

"Luckily Craig Dack took me back in a way and at this point I've just been doing a little bit of riding as well as building fitness before we start testing in a week or so."

Added Dack: "When the opportunity came up to have Jay return and ride for CDR Yamaha, we both sat down and worked towards making it happen.

"I'm confident he can regain the form that saw him win several championships with us."

The 10-round national motocross begins at Broadford in Victoria on March 30.