Topic: CB400f Valve Guides

[ThatsJoeks]

Hello everyone,
I am currently building a 1977 Honda CB400f Cafe Racer and am in the process of replacing the valve guides. I am having issues installing the new guides and have broken two trying to drive them in. They seem to snap around the collar on the guides as they are hammered (lightly) in. I have machined drifts to install them and have tried heating the head and chilling the guides. Does anyone have any experience doing this job or tips on how I can install them. I am an engineering apprentice and am trying to do as much of the work on my bike as possible myself.
Any help will be greatly appreciated

[Bodi]

I don't know about hammering them in... I have had engine shops install guides because I have no press and that's what they use.
You could try cooling the guides in dry ice, the coldest stuff commonly available and much colder than a home freezer (-110F/-79C) ... liquid nitrogen is lots colder (-320F/-195C) but not as easy to get plus more $$ plus you have to rent/buy a dewar flask for it.