So over the winter I replaced the valve seals and top end of my 400ex because it was burning a lot of oil and smoking. It now has a 11:1 compression piston. It’s running good now for the most part but has a tick. I replaced the timing chain hoping it was the problem but still ticks and tensioner seems to be good. Valves are good I’ve adjusted them multiple times and their in spec. After riding for a while it dies randomly sometimes and pops but only pops when it’s dying. It also cranks for a while before starting again. Could this be cam decompressor? What else could cause a tick like this and is the dying randomly related to it? Thanks

 

Did you check cam and followers for wear when you had the top end off, as worn cams/followers tend to make a ticking noise? I don't know the 400EX model, but Honda 350s are prone to valve seats coming loose, this makes more of a rattle than a tick and, when the seat sticks in the wrong position, the bike looses compression and is bad to start. Also valve guides can come loose, again dropping compression if it sticks in the wrong place.

 

Thanks for the reply, the valve seats and guides were good, followers didn’t have play. Could carbon buildup also cause this as there was a lot before rebuild, I cleaned most of it but could be some left? The dying along with ticking has me stumped because it doesn’t always die only after a longer ride then it happens more and does it a few times