trx425r

need some help. my buddy's shee is down and not running. about a month ago we wereout and it was running fin the first day and the second it just died on the trail. it almost started but never did . gott good compression and did a leak down test...fine. stator is working... key for the flywheel is fine but... NO SPARK anybody know how to test the coil and cdi or know of any thing else i should check out ...help