29-05-12, 06:46 PM
The parts are not exactly the same, the internal diameter of the 600 inlet tracts are a few mm larger than the 400 inlet tracts.. However the reason they fit is that the bolt holes line up and the external diameter of the carburettors are the same. It is only the internal diameters which are different.
The only way you will most likely notice the difference is on a dyno because of turblence in the inlet tract and even then it would be negligible.
Prior to fitting the 600 ones (bought from M&P at a good price) to my sons 400 I measured them with a caliper. The 400 runs better now, but it was a combination of replacing the blanking plugs for the vacuum take off point and the inlet rubbers.
Again if you are checking anything around the carburettors check those plugs as they perish and crack all the way through much sooner than the inlet rubbers.
Happy riding
The only way you will most likely notice the difference is on a dyno because of turblence in the inlet tract and even then it would be negligible.
Prior to fitting the 600 ones (bought from M&P at a good price) to my sons 400 I measured them with a caliper. The 400 runs better now, but it was a combination of replacing the blanking plugs for the vacuum take off point and the inlet rubbers.
Again if you are checking anything around the carburettors check those plugs as they perish and crack all the way through much sooner than the inlet rubbers.
Happy riding