Early 650/668 motors, such as those used in the 650 Formula, apparently used a different cam profile in an attempt to increase top end performance. As with most performance related issues, the choice of cam involves a set of trade offs. In the case of the early cam profile this meant a very 'peaky' power delivery, characterized by many members of the motorcycling press as being more characteristic of a two stroke motor. With the 668 Sport, a similar peak power level to that of the 650 Formula was achieved, with a much better low to mid range. This was the result of a different cam profile, coupled with other changes.
A more radical cam profile can be developed, and may deliver improvements in an area of the performance envelope that is important to you. Check out the extreme mods section for a discussion of a total package that includes retiming the inlet cam.
As far as I am aware there is likely to be no real benefit to fitting the earlier 650 Formula cams to a later motor. As always, if someone has done this and wants to share their experiences please get in touch with me!
Siegfried Haas, of Germany, has measured the cam from his 650 I.E. This is stamped SCA/007 and a chart of the numbers is shown below. He can provide the exact figures if anyone is interested. The chart may be not exact - as Siegfried says, "Measurement is a tricky job because there is hardly no room for the gauge, and the valve springs want to turn over camshafts and crank. So the curves are a little bit rude, sorry for that."
© Steve Carr, 2001-2007
Site created February, 2000. Last modified Friday, May 15, 2009
30 May 2005