OK, I have ended up with a set of 28 cases and a set of 21 cases. Both are in good shape and I was originally planning to build up a new engine using the 28 cases as I thought they were 21 cases (as that is what they were sold to me as) until I realised the oil pump I have wont work with these cases.

So do the 28 case provide any advantages over the 21 cases that warrent me hunting down a 28 oil pump?

As far as I'm aware it's just that middle bearing oil drip feed that seperates them.

It must help..I guess but the NSR crank isn't know for wrecking it's middle bearing anyway.
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The late 21`s came out with that oil pump as well. The way i see it the oil straight to the centre bearing must be better.

I was wondering if it was something like that. And agree it can hurt. oh well guess i am looking then

I could have one for you Mate i have bid on one yahooauctions was going to be a spare but if i get it you can have it at cost .

Or theres one here http://www.japanauctioncenter.com/view2.php?seturl=http://page10.auctions.yahoo.co.jp/jp/auction/m77973355

txs will let you know.