Anti-Wet Sump Valve (again)

Hi Ian, long time no see.(Since IOM MGP 2017. Almost 4 years since we lost Kiwi Mark. (8th)

In my experience the only real cure, apart from a tap, I'll not even think about, is a perfect oil pump.

For my final build (Dommie Racer) I had a precision engineer machine new gears (Supplied by RGM)  to the exact specifications. The new RGM gears are specifically over sized so you can do this.

Almost a year with oil in the tank and no sumping.

The problem with the ball and spring is they can stick, usually with gunge and often overlooked.

A year or two ago, there was an article in 'Roadholder' about servicing your oil pump.  It really does make a difference in preventing or delaying wet-sumping. I did this on my Dominator, which has the same pump design as the non-ohc singles, tho' I hear it's a mirror image. 

If you examine a worn pump body using a metal straight edge and feeler gauges, you can expect to find that several thou of feelers will pass under the straight edge.  You need to eliminate that.  So, lap the pump body until the pressure pump gives light friction when assembled with a smear of oil.  I also did this with the scavenge pump, though this is less critical than the pressure side.  To do this, you need to lap the pump body on wet-and-dry paper on a sheet of glass. I think I started with 120 grit and went to 240 and then 400 to finish - but it was a long time ago that I did it.  Do keep checking that you are lapping the pump evenly, not creating a taper on the body.  My pump only passes a little oil if I don't use the bike for a month (shame...), and gives 40-odd psi at a fast idle when well warm. 

...............never sumped up, even after sitting for  2 years in storage.

That’s funny as my alternator engine wet sumps, my earlier one doesn’t - both have new oil pumps! I just live with it! 

Dan 

Dan......who did you purchase your new pumps from?

Hi Phillip

The engines were built by Mike P, I’m not sure where he gets them from prob RGM or Andover. 

Dan