Does the Rocket wet sump?

[mikeg_capel]

I have been thinking about our other Captains experiences and indeed my own when I overfilled it (see previous post). Then I cast my mind back to the sixties, my Vellocette venom wet sumped (allowed oil to pass from the tank to the sump through the pump when at rest) about half a pint a fortnight. That was OK because it was predictable. My Norton Domi 99 done the same but iregularly either none or about half as much. I could never work it out. Now in my latest motorbike revival of recent times I have a Matchless 55 500 single which I love to ride (smell the past), but it also looses and gains oil. This time I am lucky enough to be in a vintage bike club and th old (I mean old) and wise heads have assured me that it all depends on what part of the pump cycle the engine actually stops on wether it will leak backwards or not. I do not have a technical manual yet (one on order) so all you spanner captains out there is this possible?


Mike

 

[lonerider]

I,m so glad my dumb question has generated so much validation of my own concerns. I,m really interested in the answer on this one!! I, asked so many tech types and they all say something similar to this mike, but lets hope a real expert arises to give us salvation!

 

[Triple Trouble]

I know that on most old British bikes the oil return to the tank is usually into a tower on top of the tank and it is possible to see the oil being pumped back from the sump when the filler cap is removed. When first started there is a steady stream of oil until the scavenge pump catches up with what has drained down into the sump. After a minute or two it becomes an intermittent stream because the scavenge pump is bigger than the pressure side. It is at this point that the oil level can be checked. If left long enough, e.g. , over the winter ALL of the oil will drain down from my Norton Commando and the tank will be empty. On Norton twins specifically the drain effect is greatly reduced if the pistons are just before TDC as this places the oil holes in the crankshaft at the topmost position and the wetsumping is negligible. Do Rockets wetsump? I have no idea but this would certainly explain the apparent oil loss. I would suggest checking the oil after a brief ride to make sure all the oil was pumped back into the tank . Remember that the tank and oil will be hot after riding though should not be too bad if the ride is brief.