I have reassembled my '99 WR400 after replacing the rings and now I can't get it to fire. I have re-set/checked the timing a dozen times and it seems to be exact but it does have a auto-decomp cam, does this need different timing? I've tried 12 & 13 pin difference. I'm not sure if it is a YZ or WR cam, how do you identify them? this one has 2 punch marks for alignment one I guess at 9o'clock and one at 12o'clock position. The cam was already in the bike and it had been running well. The cam lobes are sitting at the same angle when the marks are aligned with the head. When I try to push start the bike it backfires and won't run and doesn't even try to start when kickstarting. I've checked valve clearence, replaced spark plug etc.