1982 xs400 Engine Tapping

[LtBadass]

Hey yall.

Just rebuilt the engine on a DOHC 1982 xs400 (xj I believe). Honed cylinders, new piston rings, new valves and springs, cleaned everything up and lapped/mated valves. Started her up immediately (after 4 years of sitting) and was super excited. As I started to rev her up though I was noticing a lot of engine noise. I immediately turned her off and checked the headers to make sure they were sealing, then took out the plugs and with my ear up the holes and cranked her by hand to make sure the valves weren't hitting the pistons. Everything seemed good so I started her up again, and found the same thing. It's a very loud metal tapping noise at the top end of the engine on both side, but mostly of the left side. Very worried about bending/breaking a valve.

I did replace all the valve shims to spec but the only things I can think is that those are out of spec or that the timing plate is somehow lying to me (not correctly indicating top dead center)

Please, if you have any advice, help a brother out, I'm truly stumped and don't have the money/time to tear her down again.

Much thanks!!

 

[trzcina2]

Did you adjusted your valves properly? Maybe you were adjusting them on exhaust stroke instead of compresion stroke.

I did the same mistake with my xs400 OHC and valves were VERY loud, after adjusting them properly everything is fine.

Cheers.

 

[Lou Ranger]

trzcina2's notion sounds most probable, but, just in case, after you rebuilt it and right after start-up, did you confirm that oil was getting to the top end by loosening the gallery bolt on the right hand cylinder?
Oil should seep out - if not there's an oil distribution problem.

 

[LtBadass]

Popped off the valve cover to see what was up and holy shit...

All the bolts for the cam caps for loose as hell, has this happened to anyone?

Little lock tight on the bolts, battened her back up, and seems to run perfectly.

Thanks for the help though, the valves turned out to be within spec if not, damn close to left em alone.