Iv been looking through parts books and spec sheets and other sources and it seems the B50MX was only fitted with the "MX" cam for one year the other 2 years of production all the b50's used the standard cam. Mine is fitted with the standard cam, so the question is, was there a problem with the MX cam as in wear of follower damage ?Do they go any better with the MX cam? Also all cylinder heads have the same part number but the mx as a 32mm carb?
Yep the B50 is a bit peppier with the MX cam in it and a 32mm carb combined with a megaphone and not that ugly heavy lump of a muffler that came on the regular B50s. I have observed more worn out cam lobes on the B50 MX cam than on regular B50 cams. Might be because they are driven much harder also. The flat foot followers tend to crack in the middle on them, both the B50 and the B50MX cams from time to time. Best keep an eye on them. The smaller curved foot followers were much less prone to this sort of breakage. As Tridentman says, lots of discussion on B50.org.