85 ZN700 LTD smoking like a banshee

First off, hello everyone I'm new to this forum and until now i could find everything i need lurking. My problem begins with the first time I rode the bike. Before this i had only started it and took it around the block after I had rebuilt the carbs, worked on the spark, and got good gas going in to it. The first ride was fine until about a mile in when it started smoking bad, like James Bond smoke screen bad. There is oil dripping from my right exhaust and slowly leaking on the left exhaust. On the left side of the motor where the cylinder head meets the cylinders is leaking oil. The last place its leaking is somewhere in front of the back tire, haven't pinpointed it yet. I pulled plugs and they are definitively oil, not much carbon but then again they have 5 miles on them. I'm not sure how to proceed, one friend thinks piston ring and another thinks valve stem seals. I just more opinions. Let me know what you need to make a good guess as to what it is. When I know what else you guys need i give some pictures, I know everyone here likes those.

Thanks a ton guys.

Is this the first time it has been run in years? Has it been sitting outside for a decade? Was it just fine and suddenly started? Some background information would be really helpful.

In general, 30 year old valve seals will definitely leak. They get hard as they age. The leaking you see on the outside suggests old o-rings and gaskets.

The bike was running a little over a year ago according to the last owner and ran fine. It only started after i got a mile or so away from home but I've had it running before that. I'm thinking since i have to change the cylinder head seal I may as well do the valve stem seals and any other maintenance on the top end before i jump to piston rings being shot.

You'll know when you pull the head.
Steve

Compression test results?

Good Fortune!

haven't gotten to compression test yet, I'll have to borrow one.

lemonyguy wrote: haven't gotten to compression test yet, I'll have to borrow one.

You should adjust the valves before doing a compression test. When you do the test it's best to do it on a hot engine with the throttle held wide open.

So tomorrow I should try adjust my valves and doing a compression test, hopefully I'll get time and have the results for you all tomorrow.

Compression test may help determine condition -- extent of wear -- of piston compression rings and cylinder bores.

Unsatisfactory compression raises suspicion that the oil rings are also worn, allowing oil into the combustion chambers. Which can result in oil dripping from the exhausts and the James Bond oil screen.

Good Fortune!

So if the compression test comes back bad should I just go straight to rings?

If that was my bike I'd bust down the top end all the way to the base gasket and measure everything. Replace all the gaskets with new OEM Kawasaki brand gaskets and seals, except viton valve stem seals. Pull the valves, inspect, and lap at minimum. Replace the rings and bottle brush hone the cylinders. When doing this work it goes without saying that the valves need to be properly adjusted. Do the job right one time and ride happily for many thousands of miles thereafter.

lemonyguy wrote: So if the compression test comes back bad should I just go straight to rings?

Would perform a leak-down test before any disassembly, because a leak-down test enables better diagnosis and a better idea of what to look for incident to disassembly.

A leak-down test injects air pressure through the spark plug hole to pressurize the combustion chamber, and then determining where the compressed air escapes from the combustion chamber.

Can perform a poor man's leak-down test by introducing compressed air into a spark plug hole and listening to where it escapes from the combustion clamber. This may be done at TDC or any other cam positions where both valves are fully closed. Top dead center (TDC) is when the piston is at its highest position. An easy way to tell TDC is by alignment of the T mark with the case mark when viewed through the timing window.

May introduce a spurt of compressed air by using a rubber cone-tip blow gun (rubber air nozzle) held into the spark plug hole. And of course keep holding it in position to keep air from coming back out the spark plug hole while listening for escaping air at other places. The air compressor should not be running while listening because the noise will likely drown out any sound of escaping air.

May alternatively use a portable compressed air tank.

Air heard escaping from exhaust port indicates exhaust valve not fully closing (perhaps too tight clearance or damaged valve or valve seat).

Air heard escaping from carb intake indicates intake valve not fully closing (perhaps too tight clearance or damaged valve or valve seat).

Air heard escaping from crankcase breather indicates loss of compression past rings into crankcase (perhaps worn piston rings or cylinders).

Air heard escaping from head gasket area indicates indicates loss of compression past head gasket (perhaps due to a blown head gasket).

A leaking valve may sometimes be resolved by adjusting the clearance to within specs.

A leaking head gasket may sometimes be resolved by torquing the head fasteners when the engine is stone cold (such as after sitting overnight).


With regard to the very excessive exhaust smoking (James Bond smoke screen) and oil dripping from the exhausts --- I would suspect that worn valve stem seals may be contributing to the condition, but that worn valve stem seals are not alone responsible for the condition.

I suspect that the oil rings are for whatever reason failing to satisfactorily perform their intended function of keeping oil from entering the combustion chambers.

The leak-down test is not expected to directly address oil ring functioning. But will address compression ring functioning.
And where compression is weak due to compression ring and/or cylinder wear, it's a pretty safe bet that the oil rings are equally worn.

Even when compression is satisfactory, there's no guarantee that an oil ring isn't defective or incorrectly installed or broken.
For example, excessive exhaust smoking after a top end overhaul due to a broken oil ring.

Good Fortune!