Sump mod

[Chris G]

I have done these in the distant past but not really considered the drop or intentional restriction to increase pressure - in the lower oil supply gallery of the sump to the oil cooler outlet.
Outside in from the cooler line starts at 9.5 and reduces at that ridge to about 6.5, 30mm in.

Mark’s diag recommends taking off the bur, at that point mine is raised at the upper part to about 1.5mm. Just think boring it 7.5 to 35mm in?

[Chris G]

Maybe better if I show what I mean with real pictures.

I'm not sure if this would make a lot of difference to flow performance...but, for completeness - removing the upper edge of the bore clearly seen as that dark edge, which is actually
a fair bit of material. Certainly not up for messing about needle filling that down and I don't have a lathe.

Opinions before I give to the boy to take to work at the engineering shop.

[Lorcan]

Can't see your pictures Chris...

[DEATH_INC.]

I can't see the pics either, but if you're thinking of just boring it a bit bigger and deeper from the oil cooler end, you'll probably break through the housing and have to get another. It takes only a few minutes with a die grinder and small burr to clean it up. You can use burrs in your drill too if you don't have a die grinder/dremmel

[Chris G]

I can't find the original before images
But anyway.. the casting burr reduced down to 6.5 and oval on this and thinking it can't be a one off so they are all similar?
Entry starts at 9.5 and lower gallery is at least that. Question really is does removing that reducing restriction improve oil flow..

Never any intention to enlarge, just to remove / smooth.
Have got it finished to 8mm, and round!. Wouldn't use a die grinder, too many angles going on.
Judicious use of round file, then dremel drum, if you used a needle file you would be there for months!

[Lorcan]

This whole sump mod thing arose from a claim by MrTurbo in the early 90s that the sump was restricted and that this sort of modification would help (along with buying their T2 turbo conversion of course). This was before we identified the clutch damper issue and that a higher flow oil pump than the one the Z650 used was necessary to support the higher output engine, turbocharger lubrication and an oil cooler. Kawasaki confirmed this by using a higher output pump on the later air-cooled 750 models.

Don't worry overly about the sump mods. Yes the jointing and flow can be improved but the larger oil pump and keeping the oil strainer free of debris by sorting the clutch dampers are far more important. Oil pressure, after all, is simply a controlled leak. The more leakage you have, the lower the oil pressure will be.

[Charlie @ Evergreen]

Been telling guys that do the oil pump and relieve valve upgrade to leave the pan alone. This is the fix to low oil pressure and volume. Wont hurt if you did the mods but really there not necessary with the upgrades now.

[Chris G]

This whole sump mod thing arose from a claim by MrTurbo in the early 90s that the sump was restricted and that this sort of modification would help (along with buying their T2 turbo conversion of course). This was before we identified the clutch damper issue and that a higher flow oil pump than the one the Z650 used was necessary to support the higher output engine, turbocharger lubrication and an oil cooler. Kawasaki confirmed this by using a higher output pump on the later air-cooled 750 models.

Don't worry overly about the sump mods. Yes the jointing and flow can be improved but the larger oil pump and keeping the oil strainer free of debris by sorting the clutch dampers are far more important. Oil pressure, after all, is simply a controlled leak. The more leakage you have, the lower the oil pressure will be.

I am just going through the exercise, have thought for a while there was a fair amount of hokum about it. Don't think cleaner flow and mild enlargement can do any harm either.

Hope you're recovering well Lorcan