bike running great but oil coming from exhaust

bpchura wrote: On my last posts, the bike was out of comission because oil was leaking into the same cylinder that has issues now causing the plug to fowl, oil to blow out the exhaust, and the bike run on only one cylinder.//////Because I had to make it home when it broke down last, I rode about 20 miles on the highway on one cylinder. The problem cylinder being hauled along blowing oil around. Could that have done something to the rings? Could that cause the rings to bind or somehow leak?

I don't see how that could harm the rings but be advised on something about twins: the spark plugs are wired in series and when oil gets on a plug it insulates the gap and stops it from sparking... then the other plug can't spark either. Guess how I learned that: when my valve seals leaked oil, I would park it and oil would run down and foul the left side plug (gravity goes downhill) and the engine would be DEAD. With twins, it's very difficult to have a failure in the spark system that will fire one plug only. If you were running on one cylinder, I think there may have been another problem going on as well.

If it's not a broken ring I wonder if it's possible there is a crack in the cylinder or head or someplace allowing oil to get in.


NOTE: did you try a cold/dry compression test? Let it sit overnight and test if before you run it. Then test it after it's warmed up and see how much difference.

bpchura wrote: Sorry for this long post but I would just like to explore the possibility that somehow the rings are laden with oil and that is why the smoking is present. Is there a way to investigate this further without doing any rebuilds?? thoughts??

Well. When my Wife's Saturn had about 140k on it, I took the plugs out and washed the cylinders with spray non-chlorinated brake cleaner. That contaminates the oil so you have to change the oil/filter immediately before running the engine. That was to remove accumulated carbon, not oil gunk. If you are getting a steady volume of oil flowing into the cylinder, it has to be coming from somewhere. I know from experience with cars, it's possible to get cracks in heads that still hold compression and allow it to run pretty well while blowing compression into the cooling system and letting coolant flow into the cylinder. Bikes don't have coolant (just oil) flowing in their heads so it makes me wonder if the head has a crack or some path of oil to the cylinder.

This is really interesting. I will check out the cold vs warm compression and get back to you. And that's true. This engine really isn't that bad of shape. Its a beater for sure but internally, its got great compression and perfect valve clearance. I will investigate the compression further. I was thinking it could be the leftover oil, but it didn't stop after a ten mile ride. It slowed a lot during idle and when engine braking. It would increase with throttle. I wish it was the leftover oil... Il check it out.

Bountyhunter, Ive known that and thinking about it more definitely brings up questions. You know that feeling when the bike is missing occasionally when its running smooth and it has little hickups, jaunts in power, just kinda crappy running? Thats what I was experiencing the last time that I broke down. It ran smooth, perfect, for about 20 miles then started missing a little then more and more. Eventually it was surly running on one cylinder ( no power, dies at low RPM, obvious sound ) and oil was spewing out the exhaust and head. Maybe the plug was firing but the air fuel mixture was contaminated with oil so much so that it couldn't ignite. That must have been what was happening.

A cracked head/block was something I was looking at while I had the head off. While I recognize the possibility of that, I seriously doubt it could be something like that. I looked into getting a dye penetrate test but its pretty pricey and I doubt I would have much use of it besides this. I suppose it could be a possibility but I don't see it. The head is in really good condition and I seriously checked it out with a high power light and such. I know that most cracks are unseeable but... Im just hoping that isnt the case.

Thoughts or more info on that brake cleaner run through? I could see that helping but ive never heard of something like that being done.

Using cleaners for the top cylinder is sometimes done to remove carbon. However, it does wash dirt down past the rings so some people don't recommend it. I doubt it will help your problem. If you are getting that much oil feeding into the cylinder it's more likely a broken or collapsed oil ring or a cracked head. I don't know what else could cause it.

bpchura wrote: It ran smooth, perfect, for about 20 miles then started missing a little then more and more. Eventually it was surly running on one cylinder ( no power, dies at low RPM, obvious sound ) and oil was spewing out the exhaust and head.

That makes me wonder if the oil ring is broken. It would take a little while for the oil to feed up past the compression rings and build up. I really don't know for sure. That oil has to be coming from somewhere.

Have you tried removing exhaust to look in the ports to see if valve are soaked with oil?Did you check the guides and stems when you replaced the seals?

I suppose the only thing to do is take it all down to the rings. Like I said, it ran fine then all of a sudden had the problem. I did check the valves and the valve guides/seals. All new/in spec. Thats got to be it; oil ring. When I take it all down, do I need to replace all the rings? Or could I just do the oil ring or the cylinder with the problem? Also, do I get standard size rings or do I need to get the .05 larger or .....? This is assuming, I suppose, that the cylinder walls are in good shape and a bore isnt needed. Following that, do I need to do a light hone on the cylinders? Does the call for oversize rings following that?

Depends what you find when you check the cylinder walls. If they have very little wear, you could do a hone and replace with new standard rings. If there is wear you would have to bore up a size. If there is a broken ring, I wonder how much damage it would have done to the cylinder wall running it up and down? I had to bore mine at the last rebuild. It's actually relatively cheap. Cost about $60/hole to get the cylinder bored and the piston/ring sets are not that pricey compared to the fours.

Right on. I will probably post pics/specs of my cylinder walls when I get it all in place. Thanks for in info. Getting ready for a rebuild!