Valve guide and valve issues

[Petew]

I have begun another project , another 1980 400G. I have the bike stripped down and have begun the process of the rebuild. Everything , so far, has been surprisingly clean for a bike that has sat for so long (11 years), the pistons and cylinders were exceptionally clean and un -marked. I removed valves today to check their condition, and while very clean for a 1980 with 16000 miles, I have some concerns. First off, both intake valve guides have cracks in them( see pictures).I know they will require replacement. The valves appear to be straight when I check them with my micrometer and roll test. However, they are pitted on the top of the valves. Is this abnormal and should I , as the manual says, replace them? In auto repair in the 80's we would do a slight bevel gring to the top edge that would take care of some of the mushrooming that can occur. Being fairly new to this I am not sure what would be considered acceptable. The piston tops showed no sign of valve contact. Recommendations anyone?

 

[Petew]

Also...can valve guides be removed installed at home. I have read that if you heat the aluminum head at 200 degrees for a bit the guides will slide out. There are also sources for hand install manual drivers....any insight?

 

[BBS360]

I was looking into all the diy options to replace valve guides and none seemed ideal.
Had a shop do my exhaust valve guides and got them to cut the valve seats at the same time.
The guides can still be ordered new from Yamaha.

I'd replace everything questionable while you have it apart. Can't tell in the photo how bad the pitting is.

 

[Petew]

The head and valves are really great shape. They cleaned up nicely with very little effort. The bottom end is ,likewise, remarkably clean. I have a source for OEM guides, just was hoping I didn't need to sub it out...just a hold up

 

[Petew]

Mmmmmmm....nothing like a little cylinder head soup with your morning coffee!

 

[Petew]

Found a guy to do the remove,replace and full valve job for less than I expected. Not many guys doing machine work in my area anymore. A few years ago I had the resources and a guy to oversee my learning. Wish I still had them.

 

[spectra]

Good to hear and hope the wife didn't see that on the stove

 

[Petew]

Nope....shhhhhh!