Ive never touched a raptor so not sure on your machine but on the yfz, you have to pull the front plastic and gas tank off. (the dzuz fasteners are a must upgrade as you can get plastics off in about a minute with them) then its pretty simple. Pull of the valve cover and remove a cover on teh side of the motor to line up the timing marks. You can verify tdc with the marks on the cams lining up with the head as long as cam timing hasnt been messed with. Then just use a feeler gauge. Bent ones help a lot. If its out of spec its a bit more work, you have to back off the chain tensioner, remove the cams and then change out the shims under the buckets. My bike has 80ish hours on it and i havent had to change them as they have been within spec each time.