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WR Camshaft Swap Info


List of 5-Valve OEM Camshafts & Part Numbers

Year  Model          WR Intake Cam    WR Exhaust Cam   YZ Intake Cam    YZ Exhaust Cam   Comments1998  YZ/WR400F      5BF-12170-00-00  5BF-12180-00-00  5BE-12170-00-00  5BE-12180-00-00  WR exhaust cam advanced 1 tooth1999  YZ/WR400F      5BF-12170-00-00  5BF-12180-00-00  5BE-12170-00-00  5BE-12180-00-00  WR exhaust cam advanced 1 tooth2000  WR400F/YZ426F  5BF-12170-00-00  5BF-12180-00-00  5BE-12170-00-00  5BE-12180-00-00  WR exhaust cam advanced 1 tooth2001  YZ/WR426F      5BF-12170-10-00  5BF-12180-01-00  5BE-12170-10-00  5BE-12180-01-00  WR exhaust cam advanced 1 tooth2002  YZ/WR426F      5BF-12170-10-00  5BF-12180-01-00  5BE-12170-10-00  5BE-12180-01-00  WR exhaust cam advanced 1 tooth2003  YZ/WR450F      5TA-12170-00-00  5TJ-12180-10-00  5TA-12170-00-00  5TA-12180-00-00  Same intake cam. WR exhaust cam advanced 1 tooth2004  YZ/WR450F      5TA-12170-00-00  5TJ-12180-10-00  5TA-12170-00-00  5TA-12180-00-00  Same intake cam. WR exhaust cam advanced 1 tooth2005  YZ/WR450F      5TA-12170-00-00  5TJ-12180-10-00  5TA-12170-00-00  5TA-12180-00-00  Same intake cam. WR exhaust cam advanced 1 tooth2006  YZ/WR450F      5TA-12170-10-00  5TJ-12180-20-00  5TA-12170-10-00  5TA-12180-10-00  Same intake cam.2007  YZ/WR450F      5TJ-12170-00-00  5TJ-12180-30-00  5TA-12170-20-00  5TA-12180-20-002008  YZ/WR450F      5TJ-12170-00-00  5TJ-12180-30-00  2S2-12170-00-00  2S2-12180-00-002009  YZ/WR450F      5TJ-12170-00-00  5TJ-12180-30-00  2S2-12170-00-00  2S2-12180-00-002010  YZ/WR450F      5TJ-12170-00-00  5TJ-12180-30-00  N/A              N/A2011  YZ/WR450F      5TJ-12170-00-00  5TJ-12180-30-00  N/A              N/A2012  YZ/WR450F      5TJ-12170-00-00  5TJ-12180-40-00  N/A              N/A2013  YZ/WR450F      5TJ-12170-00-00  5TJ-12180-40-00  N/A              N/A2014  YZ/WR450F      5TJ-12170-00-00  5TJ-12180-40-00  N/A              N/A2015  YZ/WR450F      5TJ-12170-00-00  5TJ-12180-40-00  N/A              N/A

Cam specs
Per 2grimjim's post, all 03-09 YZ OEM cams have identical lifts & duration. The only difference is the lobe centerline angle (LCA). Lobe Separation Angle (average of intake and exhaust LCA) is listed as LSA. Intake & Exhaust durations are listed @.050" lift.

Cam           Intake LCA Exhaust LCA   LSA      Intake Lift  Exhaust Lift  Intake Duration  Exhaust Duration  Comments03-05 YZ      109°       104°          106.5    8.61mm       8.43mm        244°             244°              Same intake cam as 03-05 WR/04-05 YFZ.  Exhaust LCA NOT measured. Calculated exhaust LCA by assuming YZ exhaust cam is WR cam retarded by 22.5°06 YZ         106.5°     104°          105.25°  8.61mm       8.43mm        244°             244°07 YZ         Unknown08-09 YZ      102.5°     99.5°         101°     8.61mm       8.43mm        244°             244°03-05 WR      109°       126.5°        118.25°  8.61mm       8.43mm        244°             244°              Same intake cam as 03-05 YZ/04-05 YFZ06 WR         106.5°     126.5°        116.25°  8.61mm                     244°                               Same intake cam as 06 YZ.  Exhaust LCA NOT measured. Calculated exhaust LCA by assuming WR exhaust cam is YZ cam advanced by 22.5°07-11 WR      107°       113.5°        110.25°  7.65mm       7.75mm        236° (@.040")    236° (@.040")03-04 HotCams 105°       105°                                                                                 http://www.thumpertalk.com/topic/56257-yz-450-cam-mod-please-read/page-31#entry775865HotCams       110°       103°          106.5°   8.86mm       8.67mm        269° (@1mm)      265° (@1mm)       4023-1IN 4044-1E http://hotcamsinc.com/ProductInfo.aspx?item_id=574 http://hotcamsinc.com/ProductInfo.aspx?item_id=55904-05 YFZ     109°       127.5°        117.75°  8.61mm       8.43mm        244°             244°              Same intake cam as 03-05 WR/YZ

The WR exhaust cams open before BDC on the power stroke, wasting combustion power. Additionally, there is little to no overlap with the intake stroke, so the exiting exhaust gases do not help draw in new fuel during the intake stroke. More info http://www.thumpertalk.com/topic/264230-wr-to-yz-cam-timing-advantages/#entry2309905


The 2007-2015 WR intake cam has approximately 1mm less lift (~7.65mm) and ~20° less duration than the YZ cam. The 2007-2011 WR exhaust cam has approximately .68mm less lift (~7.75mm) vs the 03-09 YZ cam. The shorter lift contributes to the low-RPM power & lug-ablity of the 2007+ WR.




Varying the Lobe Separation Angle
According to Web Cam Racing-

As a general rule, tightening the LSA will:
  • Increase low-RPM torque
  • Create a narrower power band
  • Increase maximum torque

Widening the LSA will:
  • Raise high-RPM torque
  • Create a wider power band
  • Reduce maximum torque

Above 114° LSA = Extremely wide

112°-114° LSA = Wide

110°-112° LSA = Moderately Wide

108°-110° LSA = Moderate

106°-108° LSA = Moderately Tight

104°-106° LSA = Tight

Below 104° LSA = Extremely Tight


See http://www.webcamshafts.com/index_blank.html?pages/degreeing.html for further details


Decompression Specs
Per 2grimjim's post:

Model        Lift     Duration (@.010" lift)   Open (@.010" lift)   Close (@.010" lift)   Center of LiftYZ exhaust   1.63mm   124°                     30° ABDC             26° BTDC              84° BTDCWR exhaust   1.63mm   143°                     3° BDDC              40° BTDC              110° BTDCYFZ exhaust  0.84mm   79°                      28° ABDC             73° BTDC              111° BTDC

YZ Exhaust Cam Generations


Prior to 2003, the cam base circle is different than 2003+ years, and the camshafts lack the decompression pin
2003-2005 are identical, and have the most grunt
2006 has a nice balance between low-end & top-end power.
2007 shifts the power towards the top-end
2008-2009 saw a more restrictive exhaust pipe and the cam further shifted the power towards the top-end


For more info:


1998 through 2002
For 1998 through 2002 WR400F/426F's, you can simply rotate the WR exhaust cam one tooth clockwise to get YZ timing. For instructions, see MotoMan393's site here: http://motoman393.thumpertalk.com/tech/yztime.html


To get YZ timing and auto-compression, you can use a 03-05 YZ exhaust cam, but you may not use the original timing mark on the YZ450F exhaust cam. Re-shimming is required as the base circle is a different diameter. See the following links for more details:


2003 through 2006
For 2003 through 2006 WR450F's, the WR exhaust cam is advanced one tooth counterclockwise, but the decompression pin will be in the incorrect position to work correctly. A yz cam swap is required. 03-05 YZ cams are identical.


2007 through 2015
For 2007 through 2015 WR450F's,you can swap to a YZ cam.


Additionally, for e-start to work consistently, you will have to grind the decompression PIN. For grinding instructions, see here: http://www.thumpertalk.com/topic/1141940-wr450f12-how-to-grind-a-yz-cam-for-e-startability/


See n16ht5's post to see how you can retard the WR exhaust cam and keep e-start by grinding the decompression PIN.

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