Motorcycle Repair: cb650z, valve stems, head bolt

Question
Hi Bill, I recently bought a cb650z partially restored, having now finished the restoration i tried to fire the bike and oil started coming from one of the right outside head bolt, on inspection I found the thread had been stripped. Can I re-thread or heli coil if so what size can I use? Thanks, Richard.

Answer
Richard, the rocker arm cover bolts are all 6mm x 1.0 pitch threads. Very common on motorcycles and automobiles.

Heli-coil or other inserts should be fine for this repair.

Removing/reinstalling the top cover requires loosening the valve adjuster screws, so they don't hang up on the tips of the valve stems and bend the stems, especially during installation of the cover.

Bill Silver