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
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-
- Increase low-RPM torque
- Create a narrower power band
- Increase maximum torque
- Raise high-RPM torque
- Create a wider power band
- Reduce maximum torque
See http://www.webcamshafts.com/index_blank.html?pages/degreeing.html for further details
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.