Oil Consumption on 1981 GPZ1100

Question for the old timers:

Background:
Bike is a 1981 GPZ1100, 3500 real miles on it when I bought it from a widower. Her husband was the original and only owner. It had three oil changes according to the log book, 600 miles, 3000 miles, and me at 3500 miles when I bought it. I has ~2800 more miles on it now, 6700 total there about. It's basically a new engine. This bike was last licensed in 1990 before me, and was parked in a garage under a cover until sold to me. The owner stopped riding it because apparently the fuel injection system failed and he could not get it running again and bought a different bike and road it instead. No corrosion that I've been able to detect.

The issue:
I've finally been able this summer to really put some regular miles on the 81' GPZ1100 project bike. I've been commuting about 500 miles a week on it for the last month and half. I've added about 1.2 quarts to it in that time; my question is this a normal consumption rate for these engines? No oil leaks that I can find, doesn't blow smoke that I can see, crankcase vents typical oily mist but not quarts. I don't vent to a catch can..yet. Compression was strong, plugs are clean. The engine runs great pulls like a tractor.

My theory:
I have no idea how this guy broke in the engine, so to be on the safe side, I've been running non synthetic oil for at least 3500 miles to try and re-seat the rings on the chance that the cylinders may have been rusty . My commute is on back country roads in the prairie where I can really stretch her legs (read WFO, she really pulls like a hauss ), so crank case pressures might be higher than a normal ride.

Conclusion;
I believe, that the rings may not have been seated from the original owner, or surface rust has caused them to not seal 100%. Running high pressures will force the rings tight against the cylinder walls and hopefully seat or re-seat them. I know air cooled engines run looser tolerances than water cooled, and I would expect greater oil consumption (which is OK as this replenishes with clean oil). However, this is my first large air cooled bike, and I don't know what "normal" should be for these engines. I don't remember my gpz550 using very much, but that was 30 years ago.

Question:
From those that have more experience than me with these engines, what should be the typical oil consumption, all things being equal(IE: assuming this is a new engine and in good health)? Sorry for the long winded explanation/background, but understanding that oil consumption can be based on many factors I wanted to give a decent description for the experts.

Thanks
577Nitro

1.2 quarts in 2800 miles isn't terrible, but it's not great. Maybe the valve stem seals are hard? You might want to check compression. If it's good most likely the rings are okay (although they could have some carbon.)

Agree on the valve stem oil seals, We are talking 40 years now, even if the bike has not been run much. ….rubber gest old anyway, and with so little mileage they would get dry.

The early J motors had cylinder problems from the factory. A lot of them were oil burners and Kawasaki repaired a bunch under warranty. The cylinders left the factory with an oval instead of round shape. This could be one of those.

baldy110 wrote: The early J motors had cylinder problems from the factory. A lot of them were oil burners and Kawasaki repaired a bunch under warranty. The cylinders left the factory with an oval instead of round shape. This could be one of those.

Curious how the out of round cylinders were repaired, and would a cylinder block like that work for an 1135 piston kit?

They usually were simply bored to next size and new pistons / rings.

If I read correctly, and 1.2 quart in 3000 miles, you have a good one. Kawasaki claimed a quart every 600 miles normal at the time. Warranty for oil consumption was for engines that used much more than that. If you can ever get 1000 miles to a quart consider it a blessing. I loved my GPZ1100 and wish I still had it, but they had problems, many of them.

If starting out fresh with straight and round cylinders, what should be the expected miles ridden per quart of oil use?

My 44 years old bottom end Z1B engine with new rebuild top end J1000 head needs 0,400 Liter = 0,422 quart of oil in 1000 miles = (1600 KM). A new bottom and top rebuild engine should need less than 0,200 quart/1000 miles after the break in time.

Scirocco wrote: My 44 years old bottom end Z1B engine with new rebuild top end J1000 head needs 0,400 Liter = 0,422 quart of oil in 1000 miles = (1600 KM). A new bottom and top rebuild engine should need less than 0,200 quart/1000 miles after the break in time.

Please explain how an original and untouched bottom-end with no leaks contributes to oil consumption.

I thought most if not all oil consumption would be attributed to worn cylinders, rings, and/or components in the head.

daveo wrote: If starting out fresh with straight and round cylinders, what should be the expected miles ridden per quart of oil use?

5000? Maybe more...

One factor that affects oil consumption is the level and depth of crosshatching in the cylinders. A prime example of this is the Cadillac Northstar V8 engine. Those engines typically used oil at a rate higher than most car engines. Years ago I owned a 1997 Cadillac Seville that had about 25,000 miles on it when I bought it. I kept it until it had more than 220,000 miles. During that time it used about 1 quart of oil every 1,200 miles or so. It used that much when I bought it and it used that much after it had 220,000+ miles on it; the oil consumption never varied. From what I read that was not at all unusual for the Northstar engine and may be attributed to the type of cross hatching on the cylinder walls. It was a great car with plenty of power, and if not for the electronics that could no longer be obtained I would still own it. I don't think the Seville's oil consumption could be attributed to my driving habits since my other cars and truck use virtually zero oil between oil changes. Ed