Sump Drain Tap

Pre '72 and post '73 are catered for by RGM and others with the 'magnetic sump plug'. This has a smaller secondary plug in the large body. 

If it is a '72 then I don't know, other than a new oil pump to slow things down.

Me? I have now fitted the Kingpin oil tap to my bike - with cut out switch so cannot start with tap off - to stop wet sumping on my Dommie.

Regards,  George 

Whatever might be attempted along these lines, you will certainly want a solution that can be relied on not to open itself while you're riding along.

that a sump drain tap is a good idea. A couple of thoughts:

1) As pointed out by Julian and given that you're posting in the 'Commando' forum, the considerable engine vibration could open the tap when riding.

2) You could forget to close the tap.

3) If the tap is bulky, it could get damaged easily.

4) Even with a tap fitted, you're still going to be grovelling under the bike and also increasing the opportunity for grit etc. to contaminate the draining oil (and thus adding it back into the oil reservoir).

I agree with George that the better solution is to stop the oil filling the sump in the first place by fitting the 'Kingpin-type' tap with the electrical cut-out. I'd suggest that fitting a new/reconditioned oil pump will only slow wet-sumping and not prevent it totally (from experience).

Sump drain tap?  Odd how the technicians don’t fit that type of ‘solution’ to aircraft…

I saw an article many years ago about a solution on a wet sumping Matchless single. The owner had fitted a 12v windscreen spray motor into a permanent pipe running from the sump plug to the tank. Before he started the bike he operated the pump until the sump was emptied back into the tank, it was not needed again until his next first ride of the day.

Permanently plumbed in so unlikely to come loose.

No restriction on the oil feed pipe to the engine or valves or taps to go wrong.

No risk of dirt being added to the oil.

If you forget to operate the pump before the first kick is the only issue which would not ruin an engine only make starting difficult.