Oil Pump Rebuild??

Does anyone know if a KZ oil pump can be rebuilt? I'm rebuilding the engine and a new oil pump seems logical, but very expensive I'm sure. It seems that they should be rebuildable, but I don't ever remember seeing parts for a rebuild.
Thanks

take it apart and blueprint it.

The oil pump probably doesn't need to be rebuilt. It is basically a larger gear driven directly off the crank and unless the teeth are broken off the gear, there wouldn't be much to rebuild. I suggest you remove your oil pump and clean it out and inspect the strainer mesh but other than that, I don't think you will need to mess with it.

take it apart and clean it,look for broke teeth.clean up any burrs on gears and housing make sure top and bottem of gears are flat and pump cover are flat.a piece of flat glass and fine sandpaper works good. goodluck,happy wrenching!

A gear pump can wear and produce reduced pressure. The theory of operation is that the pump is a "positive displacement" type of pump, with each turn of the shaft producing the exact same volume of fluid output, irrespective of the back pressure at the pump outlet. It does this by carrying the fluid in the space between the gear teeth and the pump wall, and having it squeezed out of that space when the gears mesh. However, if there is excessive wear between the gear teeth and the pump wall, or between the gears where they mesh, the oulet pressure will cause fluid to bleed back to the inlet side of the pump, with the net effect of reducing output volume and engine oil system pressure.

The easiest cure for this problem is to replace the gears with new. However, if there is significant wear on the inside of the pump housing, even new gears will not bring the pump back to original design output.

Now for the practical approach: In my experience, the only oil pumps that I have seen with major gear and pump housing wear are those that have experienced an extended dry run (i.e., such as when the motor is run without oil). Most other times low oil pressure in the system is is the result of excessive clearances in other portions of the engine's oil distribution system (usually the bearing clearances).

I don't know if the workshop manual has any measurements you can take to determine if your pump is within specs. When I get home I will take a look.

I have very little experience with the big bikes, but here´s the innards of a KZ 650 oil pump I took apart.
Like George says there´s not much to rebuild, the manual tells you to measure some tolerances and replace the unit if the specs are off, that´s about it.

This particular engine broke a valve and holed a piston, so I wanted to check the pump for debris and flush/blow out the screen from the inside.



Post edited by: onkelb, at: 2006/03/02 13:22

Based on the fineness of the screen, I am guessing there was no debris in the oil pump itself. Onkelb, was there anything in there? Just curious... btw; The o-ring pictured isn't actually inside the pump.

Awesome info so far, thanks! I used to build gear pumps (fuel pumps for jet engines) but didn't realize that our little oil pumps were gear pumps too. I haven't had the pump apart yet. I have a modified pump with a long intake tube that goes to a deep sump pan. I was going to convert it back to stock type, so I bought a used pump on ebay a while back. I wanted to check it out before I put it in my newly rebuilt engine. :blink: I'll have to take it apart and check my manual. I just wanted to check with you guys first because there is always a great pool of knowledge available here. I wonder how close the 1000 pump is to the pictured 650 pump?

There wasn´t any debris inside the pump, just wanted peace of mind. There was quite a bit of droppings in the oil pan as you can see below - the lump next to the oilpan used to be no. 3 piston. :pinch:

And no, the o-ring is not inside the pump, it sits between the oil pump and the oil pan right in front of the oil filter (on the 650). Not shown in the pic above is the paper gasket that goes between the pump halves, it´s usually included in the engine gasket kits (Vesrah´s at least) as is the o-ring.

Like I said, don´t know much about the big bikes, but I would suspect a similar design.

On my turbo bike, the case sides were lapped slightly to tighten the tolerances between the gears and the case to optimize the pump output.

Jeff.Saunders wrote:

On my turbo bike, the case sides were lapped slightly to tighten the tolerances between the gears and the case to optimize the pump output.

Wow! A performance mod for the oil pump! The things you learn on this site...

OnkelB wrote:

There wasn´t any debris inside the pump, just wanted peace of mind. There was quite a bit of droppings in the oil pan as you can see below - the lump next to the oilpan used to be no. 3 piston. :pinch:

And no, the o-ring is not inside the pump, it sits between the oil pump and the oil pan right in front of the oil filter (on the 650). Not shown in the pic above is the paper gasket that goes between the pump halves, it´s usually included in the engine gasket kits (Vesrah´s at least) as is the o-ring.

Like I said, don´t know much about the big bikes, but I would suspect a similar design.

Oh my!!! I can't stand the site of metal bits in oil:sick: