This is a pair (2) of Kibblewhite C630 valve guides for the Triumph 650 and 750 twin cylinder models in the standard condition. They can be used as either inlet or exhaust valve guides.
The C630 nickel bronze material provides superior resistance to wear and offers outstanding heat conductivity. Kibblewhite valve guide profiles are designed to have minimal effect on the airstream while maintaining critical cross sectional thickness in high temperature areas. There is no groove for a valve stem seal on this guide.
The valve guides require fitting to the valve stems to a specified clearance, which requires reaming and finish honing, once they are installed in the cylinder head.
Due to the 5 percent nickel content in the alloy of the C630 guides, it is recommended that the reaming and honing be done by a qualified professional with the appropriate tooling to handle the hardness of the C630 valve guide.