2006 yz450f heads

5 replies to this topic
  • billb10022

Posted December 23, 2011 - 07:17 AM


About 5 months ago I picked up a 06 yz450f for a around $1500 and did some basic maintenance (valve adj, wheel bearings, grease linkages) but am planning on tearing the engine down over the winter. I would like to have the valve seats done along with installing steel valves vs Ti and maybee wr cams for a little more added longevity and the wr cams for tamer runing motor. Anyone know a reputable machine shop in the seattle area? Has anyone else done the wr cam swap or is it even possible?


  • 2grimjim

Posted December 23, 2011 - 08:57 AM


Don't know in he Seattle area, but Millenium Technologies does great work. If you swap to SS valves, you'll also need to use a matching spring/retainer kit.

As far as cams go, the 2007 WR450 cam were the first cams completely unique to the WR. Other cams used in the WR ('03-'06) were nearly identical to YZ cams. YZ cam from '03-'09 and WR cams from from '03-'11 will fit in your bike.

The '07+ WR cams have about 1mm less lift than previous grinds and make really good low end power compared to the YZ cams. I have o set of these cams in a 471 stroker WR. They definately choke off some top end power though, but if you spend a lot of time on tight twisty trails, you'll like the '07 WR cams.

  • billb10022

Posted December 23, 2011 - 10:26 AM


Thanks for the useful info
Definitly dont spend much time in the upper range so 07+ wr cams sound like the way to go.

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  • 2grimjim

Posted December 23, 2011 - 10:37 AM


To get the most from the WR cams, I'd go with a heavier flywheel too.

  • billb10022

Posted December 24, 2011 - 11:18 AM


To get the most from the WR cams, I'd go with a heavier flywheel too.

Already got that portion taken care of. Definitely helped but I still want a little more low end grunt.

  • 2grimjim

Posted December 24, 2011 - 11:41 AM


Dyna makes a programmable CDI for your bike. I have one on my '06 YZ. Making maps for it was a little tricky. Making a blanket advance down low makes it snappier for sure but the even with the flywheel, it's a handfull in tight situations. I've been playing with advance curves at part throttle settings and have some that work pretty good now, but it was a lot of trial-and-error testing.

You can also try using an FMF Mega Bomb header. Depending on which type of muffler you are using, the Mega Bomb can make a noticable difference. The FMF seems to be the most effective at helping bottem end power when used on a YZ with a quiet muffler. The YZ's really run like poop with a quiet exhaust, considerably worse than with the same muffler on a WR. The Mega-Bomb really works good with the Q4 on the YZ. The stock '06 YZ exhaust is much better, performance wise, than exhausts used on the '07-'09 YZ's.

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