So yeah the 07 + WR450's no longer have a HP-less cam from Yamaha. The cam is the same as the current F.I. WR450.
Maybe my wording was less than optimal: I never assumed that yamaha designed a different, an HP-less cam for the WRs.
Simply because of cost, they just took the YZ cam and changed one punch mark on it and used a slightly different decomp pin shape, nothing else.
As can be seen from my pics of the '12 WR exhaust cam vs. the '06 YZ ex. cam:
when they are aligned correctly not only the cam lobes but the whole decomp mechanism and the "12 'o clock punch mark" are rotated.
It's really the sam cam, always has been. Rumor has it they changed the height of the lobes around '07,but I think
each year the WRs got the YZ cams with the 9 'o clock punch advandced one tooth and the e-start decomp pin.
They did not rotate the press fit sprocket, just the alignment punch mark, the other punch mark on "WR cams" still is where it is on the respective YZ cam.
Would make sense: you optimize the YZ year after year and mellow it down for the WRs at next to no cost by punch mark rotation.
cut out the back fire screen
Whasset? Do you mean the wire lattice trash bin shaped spark arrestor in the muffler or the lattice between air filter and intake ?
Edited by WRF-Rowdy, June 06, 2015 - 12:03 AM.