Repository containing information about parts and modifications for various motorcycles
This project is maintained by mitchellwaite
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 |
| 2020 Stock | tbd | |||||||||||
| 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 |
| Yoshi ST-1 | 0.362/0.346 | 238/234 |
I’ve borrowed most of the above table from the following page, archived by the wayback machine: