Oily exhaust valve

I removed my exhaust header yesterday to repaint it and peeked into the exhaust ports to look for anything irregular. Cylinder #3's exhaust valve on my KZ1000 is all oily, and cylinder #4's exhaust valve has some oil on the stem only, where the valve travels through the stem seal. Here is a picture of the #3 exhaust valve that is wet with oil.



It's a bit dark, but you can tell the valve is oily. What is the most likely cause... bad rings or a bad valve stem seal? The bike has around 36k miles on it, and I have no idea if it has ever been rebuilt or not. While I was in there, I checked all valve clearances and they are all in spec. All of them were at .003" except the #1 intake and #4 exhaust, which were at .002". My last compression test was done almost a year ago. The results from that were #1-160lbs #2-140 #3-140 #4-150. It wouldn't hurt to check this again, but it didn't cross my mind tonight.

I'm contemplating on removing the head and cylinder just to inspect and clean up everything. Someone put a bad paint job on this engine and it has been peeling ever since I bought it. I could also get some head work done if my valve seals are bad, or replace the piston rings if they are causing the oily exhaust valve.

I would like some input on what my next move with the bike should be. I don't mind it being off the road for a few weeks as long as I get it running how it should and looking less like a junker.

Would suspect worn valve stem seal.

Typically evidenced by exhaust smoke from cold cranked engine, with less smoke after reaching normal operating temp.

A common usually non-critical condition.

After assuring valve clearances are okay, would perform both compression and leak-down tests to help determine general condition of top end.

Good Fortune!

It's a valve stem seal leaking. The problem is that some of the valves are slightly open when you turn the engine off and the oil leaks down the valve and can gunk up the valve seat and even foul plugs.... guess how I found out about that.:huh:

Go and do a compression test, if low or uneven then a leak-down test to find the source. If all good you can get the stem seals off and new ones in with the head on the bike. If you have a air compressor you can hold the valves shut at TDC firing position for each cylinder, you may have to make up a lever and a open window tool for pressing down the springs to get the keepers off. Make sure you plug up the chain area with some rags when doing the keepers. They make special pliers for the seals to pull them more easily, but you can experiment here with different plies or hooked tools. After all you will be installing new seals. Now I usually check to see if my valve guide is ok by holding onto the stem and letting the air pressure off, then rocking it back and forth with the valve about 1/4" away from its seat. If all good slip a new stem seal into place, a small deep well socket will work, and reassemble. This is the time to think about a fresh cam chain, and it can be done in the bike also as long as the guides are still serviceable.
Good luck.

Motor Head wrote:

Go and do a compression test, if low or uneven then a leak-down test to find the source. If all good you can get the stem seals off and new ones in with the head on the bike. If you have a air compressor you can hold the valves shut at TDC firing position

I always wondered how that's possible. On my 750 twin, there is a fair amount of overlap at TDC. The exhaust valve is already opening and the intake is not fully closed yet. I could not find any position where both valves were fully closed. I always tried to find one to make checking valve clearance easier, but there isn't one on mine.

If the bike starts and runs fine, I wouldn't worry about it too much until you start to feel a performance loss. Dont Panic!

The valve seals shrink after they cool, and can let some of the residual oils soak into the carbon powder that accumulates on the valve back. Even a tiny little drop seeps through and it spreads all over that stuff.

Try pulling the header off hte bike right after riding it! :laugh: Seriously though, put a fan on the header, then puller off after a run and see what they look like - probally fine.

I sure hope I don't need to do any work to it, as I'm not sure I could really afford it after doing some pricing. I've yet to do a compression test on it, but should get around to it tomorrow. I'm actually planning on doing valve stem seals on my 95 Saturn, as it burns oil after idling for a while, so if I have to do them on the bike I may have some experience to help me a long the way. Thanks for all the info provided so far, I'm actually feeling a little better about leaving the bike alone if thats what I end up doing.

it' not that big of a deal it might start to smoke a bit on start up but it really won't have that much of an effect worry about it if you ever take the head off but i wouldn't be doing it unless you where doing a rebuild or where really picky. especally if it the expense of doing it that is holding you back. the bike will still perform well other than at start up.

Maybe I'm missing it but in those images, they seem carboned not oily thus depicting a real rich configuration in the cab jetting.

Maybe it's just the old eyes messing with me....

OMR

Well I'll chime in again,
What you're referring to, "Quite a bit of vale over lap at TDC" is 360 degrees off of the firing position. Turn the crank around 1 more time to reach the TDC mark again, then on #1 the cam lobes should not be pushing on the cam followers/ tappets.
Same is true for your Saturn engine, you can do the stem seals in the car without removing the head.

Old Man Rock wrote:

Maybe I'm missing it but in those images, they seem carboned not oily thus depicting a real rich configuration in the cab jetting.

Maybe it's just the old eyes messing with me....

OMR

This depends on how much time he spends accellerating, and how much time he spends cruising.

If your just making short quick blasts around town, and not cruising around at minimal throttle for hours, then the exhaust valves will tend to look somewhat "carbony", if thats a real word :laugh:

Its from the carbs tendency to richen considerably upon accelleration... and doesn't tend to clean up easily (takes long cruise times to minimise it.)

Or he's just plain too rich at idle, and lets it idle all the time for extended periods! :laugh:

It could also be from 30 years of operations with out knowing the bikes history of course...

What I was meaning is they don't seem "Oily" saturated in oil thus ring issues... Only carbon....