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(16-11-2010, 03:10pm)Aussie Steve Wrote: British motorcycles leaked oil due to the case mating surfaces being of insuficient width and having a verticle split on all cases. They also had exterior oil lines which were prone to leakage and dry sumps which required an exterior oil tank. This was also compounded by having case mating surfaces that were not always perfect...don't forget all British bikes used to be made by hand....like Harleys are still done today.hehehehe!!!
I agree to a certain extent, however there were several well publicised instances of the porous castings.
Believe me I know, having had BSA 650, Bonneville 750 (Porous), Commando 850 (porous), T160 Trident and rebuilt all but the T160 to eliminate oil leaks.
T160 was oil tight from day one until sold and that had an extra seam with 3 piece vertical casings.
BSA, bought 6 months old with run con rod bearings and crank timing side plain bearing due to dry sump line blow off. The vertical seam while challenging, with correct assembly can be oil tight. The Porous castings were fixed by bead blasting which also helps the vertical surfaces.
Properly assembled the dry sump tank and lines are no problem. Several Japanese models have had them. (CB750 1975 dry sump, not a drop of oil, but not great handling, though a dream compared to my Kwaka 750 triple - still have the scars).
On the Pazzo Copies I am NOT saying that all copies are cast - I've only sampled a few and there are dozens out there. Just a cautionary tale that all is not always as claimed.
Just about forgot, one factory in pictures of their manufacturing process showed waht appears to be an extrusion several metres long in lever shape which they cut then machine.