cb400f Oil filter housing

[llessur]

Would one of you fine enthusiast be able to identify an oil filter housing for me. I bought a 400f engine a while back that had previously been used in race bike and it had an oversize filter housing on it - see image
[ Guests cannot view attachments ]
Fits perfectly so I presume it was done to increase capacity, Increased cooling -greater surface are of fins, or just better filtration. has anyone seen this being done before?

[flatfour]

I've not owned a CB400/4, however my 1973 350/4 (which came out of a private collection with just 2,600 original miles on it, all by the same original owner) was unmolested and had the same large filter housing with quite a substantial metal spacer fitted.

The filter was the standard Honda item, as in other "Fours".

[llessur]

Thank you. I just did an e bay search for 350 four oil filter housing and the pictures that came up are exactly the same as the one I have.