Valve Stem Seal Cap

I am in the process of rebuilding a 1979 ST70 K3. The valve guides are shot and will be replaced in due course. On examination, both guides have been fitted with a valve stem seal cap. Part number 14731-128-000. This puzzles me, as all the books seem to indicate that only the exhaust valve is fitted with this item. I don't think that Mr Honda got it wrong on a Friday afternoon, but perhaps a previous owner did! Can anyone enlighten me?
Any help appreciated.

A valve stem seal is only used on the exhaust side on 6v OT heads.
http://images.cmsnl.com/img/partslists/ ... 3_1c51.gif

In 12v heads, you have to use 2 seals.
http://www.cmsnl.com/honda-st50-dax-199 ... ml#results

Check what type / brand of cylinder head you have.

Well, the bike is definitely six volt. As far as I know, the head was made by Honda.There is a set of id markings in the casting. HM-E5 and12 22 .This tells me nothing really. Thanks for replying, any ideas?

I'm afraid you can't tell the make by the writings on the head.
Only way to know for sure is to check the valve + combustion chamber diameters and camshaft bearing type.
If it's an original 6v Honda, someone did something wrong.
(Or maybe he replaced the valve at some point or...)

Ok. Will do some investigating. Thanks for the help.