Web Cam racing cams makes a few different grinds for the KLX 250 and 300. The best “bang for your buck” seems to be the 101 grind, but a 351cc big bore kit will make more of a difference for the same cost. If cost is not a concern, the 351cc big bore kit would definitely make more power with an upgraded cam.
Another option for 2020 and earlier KLX 250/2007 and earlier KLX 300R may be to use OEM cams from the 2020 KLX300R or 2021 KLX300SM. NOTE that I have not been able to confirm compatibility (2020 300s use different valve springs and tappets), or the exact differences in lift and cam timing. Anecdotal evidence seems to indicate a boost in peak power over the stock 250 cams.
|Part No.||Cam Gear P/N|
|12044-0786||12046-0576||2020 KLX 300R Intake|
|12044-0787||12046-0576||2020 KLX 300R Exhaust|
|12044-0994||12046-0630||2021 KLX 300SM Intake|
|12044-0995||12046-0630||2021 KLX 300SM Exhaust|
Reference Cylinder Head & Cam Differences for my notes on this topic.
|Cam||Valve lift (in.) (EX/IN)||Duration (EX/IN)||Duration @ 0.050” (EX/IN)||EX C.L.||IN C.L.||LSA||Overlap||Overlap @ 0.050”||EX Open @ 0.050”||EX Close @ 0.050”||IN Open @ 0.050”||IN Close @ 0.050”|
|Stock||0.325/0.325||260/264||212/215||111.0||110.0||110.5||41||0||37 BBDC||5 BTDC||2.5 ATDC||37.5 ABDC|
|Webcam 631||0.343/0.343||250/250||224/224||106.0||104.0||105.0||40||14||38 BBDC||6 ATDC||8 BTDC||36 ABDC|
|Webcam 101||0.350/0.350||250/250||229/229||106.0||104.0||105.0||40||19||41 BBDC||8 ATDC||10 BTDC||39 ABDC|
|Webcam 293||0.360/0.360||248/248||226/226||106.0||104.0||105.0||38||16||39 BBDC||7 ATDC||9 BTDC||37 ABDC|
|Webcam 55||0.351/0.351||266/266||241/241||106.5||104.5||105.5||55||30||47 BBDC||14 ATDC||16 BTDC||45 ABDC|
I’ve borrowed most of the above table from the following page, archived by the wayback machine: