CRF250: Press fitted spark plug tube - What does this mean?

[woodsy]

I was just reading the stats on the new CRF250X and noticed this:
- Press-fitted aluminum spark plug pipe fits between forked exhaust rocker arms, further contributing to compact cylinder head design.

Anyone wanna take a shot as to what this is? Back in 1970 I had a pressed in valve seat in my SL350 fall out and create all kinds of problems. Now, whenever I read that something suseptable to lots of heat variations is a "press fit" I start asking questions!
Any thoughts?
Woodsy

 

[Rich Rohrich]

It means there is a tube pressed into a machined boss in the cylinder head above the spark plug that allows access to the sparkplug through the top of the valve cover. It's a centrally located sparkplug, so basically the tube just provides a way to seperate the valve train (and it's oil) from the sparkplug.

BTW, the valve seats are pressed into every late model high four-stroke with aluminum heads, including this one. :)