Rocker arm not centered over intake valves

[cmills83]

I am finishing up my first engine rebuild here and when I put the head back together I noticed the rocker arms aren't perfectly centered on the intake valves. The exhaust valves are centered.

Is this normal? Also, when I replaced the intake valves and valve guides I noticed one was more of an oval than circle inside and am wondering if this is related.

 

[Jim]

.....and valve guides I noticed one was more of an oval than circle inside

Did you get a pic of that? If that guide is in fact oval, it's not usable. You really don't want a valve wobbling around inside an oval guide....

 

[cmills83]

Yeah I replaced both the intake guides and intake valves already and tossed the old ones. Just not sure if the rocker being slightly offcenter is what caused the unusual wear on the guide.

 

[Jim]

OK... phew.... thought you meant you "installed" an oval guide. My bad.
The rocker being offset isn't ideal. But I'm not an XS Guru. Maybe someone else here will chime in....
I've used engines with offset like that with no problems... just not an XS.

 

[cmills83]

Ok thanks, we'll see if someone else chimes in if not I'll just go with it.

Any idea what would cause the valve guide to wear like that? If I remember correctly it was the right side only and the valve also expanded a few mm. Improper tuning on that side maybe?

 

[Jim]

Well, it's entirely possible that the offset is what caused it.

 

[gggGary]

I think Iv'e seen many that are offset. A possible cause of guide wear is rust on a stem from long years sitting. One valve is always open on an XS650 motor.

 

[TwoManyXS1Bs]

Have a look in here:

http://www.xs650.com/threads/rocker-not-centered-on-valves.47394/

 

[molochnik]

In A&P school we were told that the rocker sits slightly off-center on the valve stem to get the valve to rotate during operation. This is to help keep uniform wear on the head of the valve and the seat.
Could be B.S., but it seems reasonable to me.