TOPIC:

Skonnie Boy wrote:

...#2 exhaust port...oil is coating the inside of the port pretty good...am I looking at a new piston, piston ring(s) or piston sleeve? I'm guessing the only way to definitively know is to dig in. Thoughts?

Oil seepage down around the valve stem and into the port is perhaps resulting from just a worn valve stem seal, and then escaping past the exhaust gasket to the cylinder fins.

In the photo, it appears that an old exhaust gasket is still embedded there inside the port area. Would use a pointed tool to remove it.

Would also check the other ports to assure no old exhaust gaskets are encrusted inside. They are sometimes difficult to detect when all carboned and mashed up inside there, so use the pointed tool. Sometimes in a pinch, two old gaskets are used instead of one new gasket when reassembling.

Re-assemble exhaust headers to engine, using four brand new oem style copper exhaust crush gaskets. And perhaps enjoy leak free operation thereafter, with maybe some exhaust smoke for a few moments after first starting cold engine (a typical and usually non-harmful symptom of worn valve seals which may be later replaced whenever the engine head needs removing for some other reason).

I use Permatex High-Temp Copper sealant from a squeeze tube to tack the copper gaskets in position inside the exhaust ports while installing the header pipes.

Good Luck!

Z1 Enterprises carries the copper crush gaskets.

Click here > Exhaust gaskets from Z1E

Good Luck!

Right you is, Patton. I actually have a new set of copper gaskets, having noticed the particularly crappy seal the old ones gave. Just too lazy to put them in until now.

Might just so some light riding until fall and then tear into the engine for real, clean valves and possibly replace stem seals. Its a ratbike with some serious crash history, so the smoke behind me will match the bike nicely.

For real, the gas cap has 3 spots of road rash on it.

Thanks for the advice, all. Most helpful.

sounds like alot of oil for valve guide seepage.Hope its that simple. At least you know your exhaust valve stem is getting oiled enough.

Hard to say. It might have been a halfway between golfball and baseball sized stain. We'll tighten up the headers and try a longer test.

Well, longer running, not longer from home. I've pushed enough bikes lately.

Here's a picture that says it all about our luck of late.

The low compression would probably be due to the fact that the throttle was completely closed when tested. D'oh.

I'm pretty sure that a set of new valve seals might do the trick. And unlike my cb750, I can replace them without actually removing the engine from the frame. Question is, are the seals interchangeable from different models? Gonna try to source some locally before I order from Z1 or bikebandit.

Thanks again.

I'm thinking the valve seal is the culprit as well. I've seen KZ seals literally split in two.

TerryK wrote:

I'm thinking the valve seal is the culprit as well. I've seen KZ seals literally split in two.

One of mine "popped it's top" like the cap off a beer bottle. The machinist who did the head showed it to me.....

This thread is back from the dead!

Seems easier to pick up the old thread instead of explaining everything again.

So I installed new valve seals, valve stems seemed solid with no rocking or lateral movement on the valves. And STILL the oil does flow from the #2 cylinder. Dammit.

So I tore into the jugs and am measuring rings, pistons and cylinders. Everything is within spec, EXCEPT for the top cylinder bore measurements. They're out-of-round to the tune of .16mm - .30mm. Within spec is .05mm. But there's no oil leak from the other cylinders, and the guilty #2 cylinder is just as oval as the other cylinders.

The pistons look gorgeous. The odometer says 28K, but you wouldn't know it from the piston crowns. There's virtually no scorching, no evidence of prolonged blowby, even on the guilty piston. Sleeves look clean, visually anyway.

Could the oil leak be coming through the head gasket, from the cam chain galley?

From everything you have described, it sounds like a loose valve guide. Or worse, a cracked valve guide pocket.

Well, its all apart, so checking anything is a breeze. Hee haw.

Skonnie Boy wrote:

...oil is dripping out of the #2 exhaust header....

Skonnie Boy wrote:

Its a new plug so there's a hint of soot on the tip, but the threads are coated in oil...

Skonnie Boy wrote:

...installed new valve seals, valve stems seemed solid with no rocking or lateral movement on the valves. And STILL the oil does flow from the #2 cylinder....

If #2 plug still appears so clean, #2 cyl might not be combusting, perhaps due to over-rich mixture, with the resulting gas-oil-carbon goo escaping past the copper crush gasket.

How does #2 combustion chamber and top surface of piston compare to the others? Is there evidence of equal combustion in #2 as compared to the others?

If anything was still escaping past the #2 copper crush gasket, there's an issue with fitment of the #2 header pipe, for whatever reason.

Any and all of whatever exits #2 exhaust port is supposed to remained contained within the exhaust system until emitted from the muffler.

Reportedly, on some models, an oil channel runs close to bottom of the exhaust stud hole. And re-threading the hole may unknowingly tap into the channel, which allows oil to seep past the stud threads and onto the engine fins. (Which isn't escaping past the copper crush gasket). But that's not a likely suspect in this case, at least not yet.

Good Fortune!