oil pressure low

Oil pressure relief valve? I didnt think older KZ's had that,isnt it just open from the oil pump gears out to the end of the pump? I havent seen any springs/check valves or anything that would "set" the oil pressure other than what the turning oil pump gears will do.Is my oil pump missing something?

The gauge is new and seems accurate (0-15 psi).Kawasaki put the engine together in 1980.Can the oil journals be cleared with air pressure on a fully assembled engine? or do you mean like blowing air thru the crankshaft holes and passageways while its apart? can any of it be cleared that way on an assembled motor?

wiredgeorge wrote:

Take off your valve cover and look at your cam shafts. Any signs of wear on the lobes? Are the pockets in the cylinder head where the buckets lie full of oil. I doubt you have a problem. The oil pump on a 903/1015 pushes enough oil up through the oil journals to keep the cam shafts wet and there is very little pressure. I wonder how accurate a pressure gauge is with little pressure. If you are the one who put this engine together, did you make sure the oil journals were clear using compressed air?

The gauge is new and very accurate actually (2-15 psi).Kawasaki put the engine together in 1980.Can the oil journals be cleared with air pressure on a fully assembled engine? or do you mean like blowing air thru the crankshaft holes and passageways while its apart? can any of it be cleared that way on an assembled motor?

the only preasure releaf valve that i know of is an oil bypass in the oil filter cavity.if the oil filter plugs the oil preasure will build and push the spring and ball up to allow flow.
it is normal to have more preasure when the oil is cold and thicker and as it warms up the preasure will drop.u said u do not have the o ring on the oil pump ? if there is oil leaking there it will loose preasure.
where did u read that the 84gpz pump fits the kz? i like that.did u find that they look identical? is yours a mk11 type motor?
do u have oil at the valve spring area ,as George suggested?
What was the gear to body clearance,and gear to lid clearance, in the oil pump when u measured it?

Jeff.Saunders wrote:

Several thoughts for you...

Pull your oil filter and make sure there is both a spring and a washer under the filter.

Pull your oil pan and clean the oil pickup mesh screen.

If you are running an oil cooler, remove it. The cooler will reduce effective oil pressure.

Have you made any modifications to the bike?
Some people put shorter rear shocks on the bike and lower the rear - this also moves the oil further back in the pan.

Thanks for the ideas Jeff.
It does have the spring and metal washer under the oil filter.The pan has been off,replaced pump with another used pump,after taking it apart and looing inside,no obvious wear/tear.replaced the rubber o ring that mounts between pump and engine.Used a new K&N oil filter and fresh 20-50 oil.Havent checked for oil up inside the valve cover yet,if it was retaining oil there,wouldnt it leak around the gaskets or flood around the valves and get sucked in around the valve stems and go into the combustion chamber and smoke out the exhaust? The oil cooler was installed summer of 1980,the oil light just started coming on recently.Stock configuration KZ1000A4.
Removing the oil cooler made no difference at all,same pressures with or without it.

mark1122 wrote:

the only preasure releaf valve that i know of is an oil bypass in the oil filter cavity.if the oil filter plugs the oil preasure will build and push the spring and ball up to allow flow.
it is normal to have more preasure when the oil is cold and thicker and as it warms up the preasure will drop.u said u do not have the o ring on the oil pump ? if there is oil leaking there it will loose preasure.
where did u read that the 84gpz pump fits the kz? i like that.did u find that they look identical? is yours a mk11 type motor?
do u have oil at the valve spring area ,as George suggested?
What was the gear to body clearance,and gear to lid clearance, in the oil pump when u measured it?

I didnt measure the clearances,whats a good way of doing that? It has the black A4/MKII style engine.The only O ring i know of on the pump sets into the block and seals where the oil pump outlet hole is,Is this what youre talking about or??...

The motor has a lack of oil pressure, right?

I don't have a manual for the pre 81 1000's, but if I recall correctly, the oil pressure sending unit taps into the main oil gallery under the carbs. Is this correct?

There are only a limited number of things that can cause low oil pressure, and I'll list them by number.

(1) restriction between oil supply (crankcase) and pump.

(2) Bad oil pump

(3) Restriction between oil pump and oil pressure sending unit.

(4) Excessive clearance somewhere in the oil path.


Numbers 1 and 2 are probably eliminated because you have replaced the oil pump and there was no change.

Number 3, I don't really know how to test (wish I had a manual in front of me). If you can remove the oil filter without draining the oil, you could do so, and then crank it over to verify oil flow (should be oil pouring out the bottom of the oil filter cavity, don't forget the pan to catch the oil).
The passageway that poured out the oil in the last step is the one from the oil pump, the other passage (look for a hole) will be the one going to the main oil gallery. To check that oil passage, you could remove the oil pressure sending unit and shoot compressed air into the exit passage in the oil filter cavity. Then just see if air is blowing out the oil pressure sender hole.

Now the "Oh Crap!" one, number 4.

The only clearance that can be checked without disassembling the motor is the cam bearings, to check anything else will require removing the motor from the frame and disassembling it. So you may as well do the easy check first and check the cam bearings.

The manual should have an oil flow path diagram in it, study that diagram and figure out where the oil goes and where your problem is likely to be.

I "really" wish I had a manual that covered the 1015 cc motors, I could probably be of more help if I had one.

Thanks, i'll try the air thru the oil filter passage trick.The oil light and the oil gauge are really consistent,so its not like the light is coming on when it shows some pressure,and when the gauge shows 0, the light does come on.I keep thinking oil pump problem,like it gets hot and the aluminum expands and has clearance from the oil pump gears, or something.Or the cam bearings, i dont know what all is involved in changing them with the timing chain going over the cams and all.
Someone told me to try running Valvoline 50 wt. racing oil in it, i havent decided whether to try that or not yet...seems kinda thick,but maybe it would handle the heat a little better.One of the other posts mentioned replacing the "rotors", i guess he meant oil pump gears,that could be worth doing if they are even available anywhere,what are your ideas on that?

I'd say that since you have already replaced the oil pump, and it had no noticeable effect on the problem, that it's probably not the oil pump.

I think oil pump problems on stock KZ motors are exceedingly rare, and the odds of getting another pump with the same problem are really slim.

There are top and bottom bearing shells on the cams, if a bottom one is bad, it's more than likely going to show up on the top half as well, and you can remove the cam caps to check the bearings without having to deal with removing the cams.

Keep in mind that I specialize in the 750's (fours and twins) not the 1000's, and the smaller motors are quite different than the big ones, but I am also a mechanic, and have been one since cars had generators and distributors had points

So my advice is based on a lot of automotive experience, plus what knowledge I have picked up about the big KZ motors. I wish Z-doc was still around, he's been a motorcycle mechanic for a lot of years and may have seen this problem before.

I'm sticking with checking the cam bearings for the moment, but I'm going to see if I can contact Z-doc and see what he thinks.

Can the cam bearings be changed without upsetting the timing chain position,or shim adjustments? If i could just loosen the holders and slip the cam bearings out one at a time or something might be easy enough to do.

If they are bad something else is wrong. 77 FSM shows same 2.8 oil pressure as later model

I don't recall reading how many miles are on the bike, but if it's a lot of miles, or if the bike has been wheelied in the past, then I could see the cam bearing being the cause of the problem, instead of a symptom. I don't know the history, so I'm only saying it's a possibility.

Z-Doc said that when he's seen that problem, it was caused by a clogged pick up screen, but I'm assuming the replacement pump had the screen on it, and you would have noticed it it was clogged.

I took a look at the oil pump on kawasaki's parts diagrams, and it appears to me that the oil filter sits in a well inside the crankcase, and is sealed from the crankcase by a large (90mm or so) O-ring.

It occurs to me that if this O-ring were bad, the oil would escape into the crankcase and cause low oil pressure. Since you have the oil pan off (I think), it would be easy to check.