Crankcase oil

I did what you have done when I started stripping my 750. Thinking that the scavenge pump would have sucked out almost everything from the crankcases, I was suprised that 300ml came out when I removed the big plug. Then as I wrestled the engine round on the bench another 50ml must have slipped out where I didn't need it. Some of that would have been from inside the crankshaft. This is worth thinking about if you are doing an oil change because not draining the crankcase will leave 350ml of dirty oil in the system. The scavenge side of the pum can only remove what is in the very bottom of the crankcase until shutdown, what drains down after shutdown plus any wet sumpung drain back will just stay there.

If anybody else is about to do a Commando oil change can they measure what comes out of the sump plug and let us all know? TVM

Hi,

If you have just warmed the engine and done an oil change then there will still be a remarkable amount of oil stuck in the head and on various surfaces. To get all the oil back into the tank you need to have the engine really hot, as in after a few quick miles. If you are not wet sumping then just leave it to cool enough to not burn you then drain. You will find there is very little oil left in the sump.Tony

Previously wrote:

i changed the oil today after warming the engine up and was suprised by the amount that came out the crankcase,the engine has an anti wet sump valve fitted for over 10 years no problems.i just wondered if anyone knew for sure how much should be in there?,then i can drain it again and check it properly cheers for any help nick

Hello you are worrying unnecessarily You need a good half pint too a pint of oil in the crankcase As All Norton Motorcycle are NOT dry sump when the Machine is NOT running . I do not like taps Or Anti wet sump valves in oil Line , this only masks any ware on the oil pump. On start up you need the oil in the sump too do its Job of lubricating Your Internal Parts . IE Camshaft under side of piston and barrel and most important the Main Bearings all these are NOT pressure fed All That is Pressure Fed it the Big end Shell and Rock gear yours Anna J

Valid point Anna but it is nice to change all the oil and not just 2/3rds. Probably worth draining the sump at the same time as the tank and then pouring 250ml into the inlet rocker cover and letting it drain down for 15 mins before starting.