OK sorry guys but this is frustrating the heck out of me. I'm working on a buddy's 2005 WR250F. It had a lot of top end noise so I adjusted the valves (one of them was way loose??? Why would a valve loosen? OK never mind, its in spec now and that's not my real question here). It was also hard to start which I figured is due to dirty pilot jet etc (this bike sits a lot more than it runs). Anyways, valve clearances are all in spec now and when I set the timing I can not get the dots to line up as they should. I also went through the carb and cleaned it all out, set the AP timing. I put it together with the timing as close as I could get it and it runs like crap - starts right up on the choke now but won't idle, backfires - runs "ok" if you're revving it but won't run 'clean' until you rev it to maybe 2500 rpm - anything less and it wants to die. I'm not a newbie when it comes to working on bikes so I would think the carb is ok but I'll likely pull it and blow it all out and check passages again. And no, I didn't look at the cam marks prior to pulling the cams to change valve shims - dumbass move I know. Attached a pic of the cam timing - I've read enough on here to see that it is timed to be "WR" timing (13 links between marks on the cams) and not YZ timing (12 links). I have no idea if this is a YZ or WR exhaust cam - my buddy bought the bike used. No idea how much time is on the bike. I went ahead and ordered a new cam chain in case this is stretched, but for now, my questions: 1: Anyone know how to ID the cam to know if its YZ or WR? 2: Does this cam timing appear correct? The flywheel mark is spot on with the notch in the inspection hole when this pic was taken. See how the intake cam looks like its a little retarded? I chalk that up to cam chain stretch but what do you guys think? Thanks!