Motorcycle Repair: honda xr100r, valve clearances, leak down test

Question
Hey Mark
I recently rebuilt my son's xr100r. It had a damaged camsprocket/camchain, replaced rings while I was in there. Engine runs great now (good power, no smoking as before), but has a funny sound like tapping the exhaust pipe with a small screwdriver (had before I worked on engine as well). Prior to my dismantling the engine I took the bike to a mechanic who said engine would need complete overhaul which included replacing the rocker arms. I didn't replace the arms when I fixed the bike. Could that be the sound I'm hearing? The arms looked Ok to me, but I don't know what new rocker arms should look like.
thanks for your help.

Answer
Hi Rick,

I suspect excessive valve clearances are the source of the tapping sounds. Follow the procedures for adjusting valve clearances.

If clearances are within specs and tapping is still present, look into a damaged valve and valve seat. Perform a cylinder compression and leak-down test to verify condition of engine.

Visit "www.bikebandit.com" click "OEM Parts" to view exploded parts microfiche and parts prices.

Respectfully,
Mark Shively