The replacement for the 250cc class has come full circle, with a proposal from the manufacturers' association for a one-make engine regulation, announced by the FIM at the same time as the new MotoGP regulations.This was an idea rejected during the fierce debates about the changes last season, in favor of production-based 600cc engines. It has returned, possibly because of the need to distance the new class from World Superbike's Supersport 600cc championship.A special one-make engine could more easily masquerade as a true prototype, whereas the "Dornatypes" of the previous plan only really had prototype chassis.This is a blow to several chassis manufacturers who have already started work on Moto2 machines, under rules that allowed any 600 four-cylinder production engine. MSMA spokesman Takenao Tsubouchi confirmed that a single-engine had been discussed at the early stages."It has come back again because of the financial situation," he said, adding that it was also in line with the original intention of the class, to provide competitive racing at a low cost. "MotoGP is the main priority for all manufacturers, and we agree it is not necessary for factories to compete in the second and third classes. A single engine supplier would offer cost stability and more fairness."The next stage would be as for the spec-tire rule with Dorna and the FIM asking companies to indicate an interest in supplying engines."It needs to be done in the next one or two months," he said. "If no manufacturers are interested, we will go back to the current plan, for production-based 600cc engines, but perhaps with more controls to keep costs down. It should be decided by the end of June."The Moto2 class remains shrouded in some uncertainty. It is expected to start in 2010, with 250cc two-strokes allowed to run alongside the new four-strokes for one year only. However, it may yet be put off for one more year, as originally planned; or the two-strokes may be killed off at the end of this year.