WR400 timing issues

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.

Are you sure the bike was a TDC when you timed it? Is the bike getting spark when you kick it? Just a couple things to think about. Sorry I don't have a firm answer for ya. Mine is appart right now so I hope I don't run into the same trouble.

I have checked and it is definatly TDC and yes it is getting spark. I have just been out trying again and manage to get a backfire when kicking it over, so have been moving the cams 1 tooth at a time 12 - 13 & 14 pin spacing but still just get a backfire through the exhaust.

Did you check the marks on the cams a truely flat against the side of the head. Sounds like timing. Good Luck. PS I made my own flywheel puller for my WR today.

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