still having issues...any ideas?

[newbie851519]

I got the bike to stop popping, and it runs a lot better now.

One problem:

Took it on a 500 mile road trip, and it's burning oil. It burned about 1 liter in 500 miles. I'm using Castrol GTX 10W40, and did an oil and filter change before the 500 mile trip. You can tell by the abnormal white exhaust and smell, and the drop in oil level. It for sure isn't leaking from the oil pan (there are no drips from the plug on the pan or the filter compartment), and it doesn't seem like it's bad cylinder gaskets or rings. The reason I don't think its cylinder rings is because they were all replaced within the last 3 years. I think that there's oil getting into the carbs somehow and sucked in that way. Before the trip I thoroughly cleaned out the aibox, and the filter, and unclogged the breather compartment in the airbox where the breather hose feeds in. The breather hose is new. It did drip a little oil out of the drain hose from the bottom of the airbox a couple of times on the trip. I am not overfilling it. When I park it on the sidestand, it burns oil mostly from the exhaust on the left (where it leans when on the stand). If I put it on the center stand, both exhausts show oil burning.

So, it must be pushing oil into the airbox from the crankcase, right? Why would it be doing this? And how do I fix it? Any help is much
appreciated.

I searched, but couldn't find any answers that way, and I know I asked this question before, was told to clean out the airbox and breather setup, which I did, but it's still happening.

Thanks!
-Nick

[chef1366]

Probably a valve stem oil seal. Pull your plugs and see which one has oil on it (or ones). If you are not fouling plugs out too bad I'd save that job for the off season. You'll have to pull the head and the valves. The seals are under the valve springs over the guide. Easy job if you take your time and do it right. You'll need a valve spring compressor and a new head gasket.
If it smokes at startup and during long idle times it's more than likely the valve stem seals. If it smokes all the time and more so under load it's more than likely your rings.

Read more into your post and you say it burns oil on it's sidestand on the side it's leaning. This means oil is up into the cylinder area and the rings aren't sealing it. Maybe after the ring job they never seated properly?

[GS850_Coug]

The breather system was described to me by a professional mechanic about 4 years ago. Anything coming through the breather (whether it is oil, air, or oil vapors in air) is a direct result from blowby into the crankcase. The more travelling through the breather, the more blowby you have. Keep in mind that blowby happens on the compression stroke. If you had bad valve seals, blowby on the compression stroke would be pushing through the carbs, resulting in burning oil from the carbs/airbox. Bad rings would cause the blowby back through the breather tube and into the airbox that route. Either way, it's going to show up with a compression test. Do the compression test and you should have no problem isolating it.

Good Luck,
Torry

[newbie851519]

Thanks, this seems really helpful. There are a couple of things that me, being new to this mechanical endeavor, doesn't quite get...
Coug,
-What exactly is blowby? Is it normal? (I'm guessing that the amount that I have isn't)
-Why would the blowby go through the carbs on one hand, and the breather on the other?
Chef,
-What do you mean by the oil is up in the cylinder area? Where is the oil supposed to be in this area and where might it be in mine? And how did you come to this conclusion?
-What do you mean by the rings never seating properly? How would one seat the rings properly? (I didn't put in the new rings)

-Both of these seem like rather time consuming endeavors for a novice...How important is it that I fix this?

Sorry for the excess of questions, just trying to learn as much as I can about this...
Thanks.

[chef1366]

When the bike is on your side stand the oil level is higher on one side.
Rings seating means that the rings seal. If the person that installed your rings didn't hone the cylinder there is a chance the rings did not seat.

[DanTheMan]

Blowby is oil vapors from the crankcase. It comes from a variety of places, ergo, valve guide seals, compression rings on pistons or worn rod and main bearings. They will all contribute to oil useage.

[Dave8338]

Another possibility, when the ring replacement was done, if the ring end gaps were not offset, there is a chance that you're getting blow-by through the gaps, causing the pressure in the crankcase.

[GS850_Coug]

Another possibility, when the ring replacement was done, if the ring end gaps were not offset, there is a chance that you're getting blow-by through the gaps, causing the pressure in the crankcase.

Excellent point Dave. I completely failed to think of that issue.

Blowby is any air (with or without oil vapors) that escapes the cylinder on the compression stroke. It is either "blowing by" the rings, valve seats, or valve seals. If it passes the rings, it looks for the easiest escape route out of the engine crankcase, which should be your breather. This takes the oil into the airbox, your air filter and eventually into the cylinder, where itis burned, causing blue smoke, usually on heavy acceleration. If your breather is plugged, it will usually find it's way out through the oil passageways in the crankshaft, until escapes into the head, where it finds its way into the intake or exhaust system. If the blowby passes the intake valve, it blows back through the intake system into the carburetor (making a nasty mess to clean when you find the issue), eventually coming back into the cylinder to be burned. If it passes the exhaust valve, it gets mixed in with the hot exhaust air and burns in the exhaust system. Typically with leaky valve seals, the oil setlles through the seals while the engine is idling or off. Then when you begin to accelerate, the oil is sucked into the cylinder and burned. It is also sucked into the cylinder when you let off the throttle and backpressure comes in from the exhaust. Hope this helps with your diagnosis!

[chef1366]

Another possibility, when the ring replacement was done, if the ring end gaps were not offset, there is a chance that you're getting blow-by through the gaps, causing the pressure in the crankcase.

Or they didn't even bother to set the end ring gap:?
Even if you offset the ring gap the rings do move and spin and they are never in the same spot that you set them to begin with.:-|

[nabrams]

Yeah, start with verifying compression. If you've got below 120 psi, then it's got to be one of the issues above. If it's at least 120 psi, then you can wait till winter to take the bike apart.