I have a 2008 WR450. Among the BIG list of mods I did, one was the stator mod and wanted a brighter light than the 35w bulb that comes stock on the bike. Didn't want to go HID. Selection of H6M bulbs other than 35W doesn't really exist at a normal price. So, I started looking at how to modify the housing to fit a bulb with more wattage options. I went with a 55w/60w H4 because it works best due to the diameter of the metal part of the bulb with the flange removed. Start by using some tin snips and cut a couple places. Then take some pliers and carefully bend and remove the flange. (It's only held on in a couple spots) It comes off quite easy. Then take the metal ring out of the headlight housing and file, dremel or in my case use a mini lathe and make the hole a little bigger just over 22mm so the H4 bulb slides in kinda snug. Now just switch the H6M connector on the wire harness and put a H4 connector and your done.
Low beam is perfect, High beam is ok