motorcycle combine robot
 

I'm trying to remember a Japanese toy it consisted of five motorcycles which would combine to form a giant robot. The main body was made up of three wheeled motorcycle and the four motorcycles would form the arms abd legs. They didn't transform into individual robot just one giant robot like a super sentia robot or go lion.

Some googling suggests you might be thinking of the mecha from Galactic Gale Baxinger, or the KO version known as Mustanger.

That could be it but I remember the middle part being yellow.