The Gap between the cylinder and head is exactly what it should be for a 400. Most definitely not a 350 top end gap.
Has no decompression valve above exhaust flange, so it is most definitely not a 360 top end.
The sand cast engine ignition and clutch covers were introduced on the 1970 MC400, but not on the 250, which continued to use up the much lighter die cast round cases until nearly the end of 1971.
That exact shape fuel tank didn't appear till the 1970 models.
Not a 69 mx frame , not a 71 mx frame. With out any doubt it is a 1970 frame, regardless of how much time it may have waited on a showroom floor, for it's first purchase.
So if it is only the forks and wheel and paint color that is tampered with?
There is SFALL chance that it is anything other than a 1970 400.
External spring front ends are never cheap on the bay.
But if you fit it with the die cast round engine covers and symmetrical Maico front hub? You now have a bike that legal qualifies as a Pre70 racer as well, as stated in the Aussie racing Bible.
Hard to know whether the transmission is close or wide without knowing the engine number prefix letter.
