'06 CDI and cams in '08?

How does the '06 CDI compare to the '08 CDI? Does it give a harder punch? What about the cams? Thanks, bill804

I figured out the '06 cdi, better low end and mid range. What about the cam shafts? I usually ride in the low/mid range unless I'm coming hard out of a corner into a long straight or climbing a big hill or something like that..

The '06 cams are also biased more toward the lower end of the rev range, although the '06 pulls pretty hard all the way through the top. They are a more subtle difference than the CDI is, though.

I suggest trying the exhaust cam with the '08 intake first, and add the intake cam later if you want to shift the power range even further.

Awesome thanks gray. I think the only 'hp mods' I'm gonna do are a Lexx end cap and '06 CDI. Will I notice a night and day difference?

Depends on what that means to you. It will be pretty obvious, mostly in the middle RPM range.

Will a CDI unir from any other other years helpo a 2009 YZ450 or is it just a CDI unit from the 2006 that a guy should stick with.

The '03-'05 all had the same cams. The '06 had the same grind, but the cams were timed differently to push the power curve up slightly. The '07 was the same thing again, with the same grind timed for yet a little more top end. The '08-'09 used a slightly different cam grind profile.

These have not been tried on an '08-'09 that I know of, and would probably have slightly less low and slightly more top with later cams, but this is how they worked in their OEM installation:

  • '03: Very, very aggressive low and mid range. Like driving a big-block Camaro in the rain. A little flat on top.
  • '04: "slightly" milder than the '03, but not much.
  • '05: "Soft" throughout the whole range, almost "sluggish". Done as a reaction to complaints that the previous years were too aggressive.

These have been used successfully in '08-'09 models:

  • '06: Good low end, strong mid range, good top end. Smooth and linear power across the range.
  • '07: A little less low and a stronger top end.

What would we do without Grayracer?

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