Need help again, oil smoke from right exhaust

[Prez]

Some related info here. http://www.thegsresources.com/_forum/showthread.php?t=125631

Basically, went through the carbs, after re-installing them I was trying to fine tune. Just as before the carb cleaning, #3 still seemed to be running rich (headpipe was cool enough to hold). So I went about leaning out that cylinder, eventually ran the fuel pilot in to a lightly seated position. Revved it up to 4k for a several seconds to burn out the unburnt fuel, suddenly it starts pouring oil smoke out the right side.

Fear is, that I leaned #3 out too much, thus overheating it quickly & scoring the cylinder or effectively "melting" the rings or valve seals there. Planning to do a compression check this evening, if I get home from my side job in time. Possibility #4 could be the culprit, since the compression was low there before, like it might have had a ring problem.

 

[80GS750]

oooh ouch man...

that really sucks...

hope you didnt do too much damage

 

[TheCafeKid]

Some related info here. http://www.thegsresources.com/_forum/showthread.php?t=125631

Basically, went through the carbs, after re-installing them I was trying to fine tune. Just as before the carb cleaning, #3 still seemed to be running rich (headpipe was cool enough to hold). So I went about leaning out that cylinder, eventually ran the fuel pilot in to a lightly seated position. Revved it up to 4k for a several seconds to burn out the unburnt fuel, suddenly it starts pouring oil smoke out the right side.

Fear is, that I leaned #3 out too much, thus overheating it quickly & scoring the cylinder or effectively "melting" the rings or valve seals there. Planning to do a compression check this evening, if I get home from my side job in time. Possibility #4 could be the culprit, since the compression was low there before, like it might have had a ring problem.

Easy enough to fix man! Pull the head, new seals, pull the jugs new rings. Seriously, its not as tough as it sounds

 

[Prez]

Just fired it up for a few seconds, #3 was firing right off (fuel pilot still bottomed out), and no smoke. Leaves me to think it's valve seals, a compression check later will confirm. Either way, if I have to pull the cylinders, I'm doing both, just might do the Wiseco 850 kit while I'm in there. Had planned to bump one or two of the 3 engines to 850 anyway, really depends on the cost of stock replacement rings & valve seals vs the Wiseco kit.

Oddly enough I build $20k diesel engines, but the thought of tearing into a roller bearing engine is intimidating to me.

 

[80GS750]

when i did a hone and stock rings in my 1000 it cost me about $45-50 for rings, circlips, and wristpins....

 

[Prez]

Well, compression readings are the same as before. After it has time to warm up, it begins to smoke...after the oil gets to the top end, valve seals it must be.

 

[TheCafeKid]

Dont be intimidated bro! The hardest part of the valve seals is honestly getting the valve keepers back in. It will make you cuss Steve and I got MRiddles 81 1100E together today, after replacing a broken cam, and finding the culprit for the broken cam. Thinking that we're in the clear, we didnt replace the rings or seals. Well, mistake. Should have done it while we had it apart. Bike fired right up, sounds great. Smoked the whole neighbourhood out with oil passing the seals tho. So, back off the head came. This time we took the jugs off too and took a look at the rings, and rehoned the bores. Its really really not hard man. Take your time, and have the manuals handy Feel free to ask questions!

 

[Steve]

Whaddya mean, we were "smoking up the neighborhood"?

Yeah it was a bit disheartening to have to do it, but it only takes about 2 1/2 hours to go from this

to this.

Tomorrow (actually later today) we will have the fun of using my smaller version of a valve compressor tool to work on a 16-valve head to change the seals.
Another 4-5 hours and it should be running again.

.

 

[skidMarkNZ]

God damn ur engines pretty n clean.

Oooo lala.

 

[Prez]

That's exactly what it looked like Steve LOL.

 

[80GS750]

the best part about these old engines is how easy they are to work on....

i feel more confident working on my 30 year old GS than i do working on my new lawn mower.....

 

[tkent02]

Some related info here. http://www.thegsresources.com/_forum/showthread.php?t=125631

Basically, went through the carbs, after re-installing them I was trying to fine tune. Just as before the carb cleaning, #3 still seemed to be running rich (headpipe was cool enough to hold). So I went about leaning out that cylinder, eventually ran the fuel pilot in to a lightly seated position. Revved it up to 4k for a several seconds to burn out the unburnt fuel, suddenly it starts pouring oil smoke out the right side.

Fear is, that I leaned #3 out too much, thus overheating it quickly & scoring the cylinder or effectively "melting" the rings or valve seals there. Planning to do a compression check this evening, if I get home from my side job in time. Possibility #4 could be the culprit, since the compression was low there before, like it might have had a ring problem.

Headpipe cool enough to hold...
It Has nothing to do with mixture.
It hasn't been firing at all. Probably due to a fouled spark plug or a bad wire, maybe that cylinder is just thoroughly flooded.

So now that pipe is full of unburnt fuel, it's going to smoke when it does fire.
You didn't do any damage running it lean, you didn't run it hard enough or long enough to hurt anything. It just has oil, fuel, whatever all over the place in the cylinder and in the pipe, it smokes when it burns out.

Get it running on all cylinders and ride it. Hard.
It needs to be ridden. A lot.
With all cylinders firing. All the time.

Compression will come up, it will stop smoking.

 

[Macmatic]

Get it running on all cylinders and ride it. Hard.
It needs to be ridden. A lot.
With all cylinders firing. All the time.

Compression will come up, it will stop smoking.

I second this. A few weeks ago after a carb cleaning I had a cold pipe. Compression readings showed 140psi on 1,2&4 and 90psi on 3. The bike also started smoking up a storm and I was sure I was going to have to pull the engine apart.

After pulling the carbs, checking (and resetting...) the float height and checking the spark I got it running on all four again. It was SMOKEY but I let it warm up and after about three cycles of starting, getting up to temp and them cooling off to where I could hold the header pipes the smoke pretty much went away. I changed to 15w40 like I used to run and the smoke was gone...at least in the garage.

I should be able to put on some miles this weekend and see but the moral of the story is not to think you need to open the engine up just because it suddenly started smoking. Even with my low pressure reading which really made me think I had a problem it turns out that all she needed was to run. Hot compression is not 150psi across the board.

/\/\ac

 

[Prez]

Headpipe cool enough to hold...
It Has nothing to do with mixture.
It hasn't been firing at all. Probably due to a fouled spark plug or a bad wire, maybe that cylinder is just thoroughly flooded.

So now that pipe is full of unburnt fuel, it's going to smoke when it does fire.
You didn't do any damage running it lean, you didn't run it hard enough or long enough to hurt anything. It just has oil, fuel, whatever all over the place in the cylinder and in the pipe, it smokes when it burns out.

Get it running on all cylinders and ride it. Hard.
It needs to be ridden. A lot.
With all cylinders firing. All the time.

Compression will come up, it will stop smoking.

On the headpipe, was thinking it wasn't firing because it was flooding. It would stall or nearly stall if you pull either #3 or 4 plug wire, which led me to beleive it was firing.

Also, after re-checking the compression last night, I ran it for a bit...no smoke until after it ran for a several minutes (time for oil to get up top or #3 to fire), appeared to be oil smoke, wife said it smelled like burnt rubber (I can't smell).

Then again, if the pipe is full of fuel I can see it not burning it off until it gets up to temp.

 

[NATEO]

Whaddya mean, we were "smoking up the neighborhood"?

.

you havent smoked out the neighborhood until you have to burn Mystery Oil out of the heads!!! this lasted probably a half hour of continuous run time. spread out over several days.

 

[Ozmiander]

Pfft, try starting a coked up GT380 on straight seafoam with MMO still sitting on top of the cylinders and pipes so gummed up that you have to pull the baffles. THAT is some serious smoke.

 

[Macmatic]

Haha, yeah I forgot that I had MMO and some sea foam in my cylinders too. Smoke city.


....maybe I can find a way to do MMO injection for tailgaters.

/\/\ac

 

[tkent02]

....maybe I can find a way to do MMO injection for tailgaters.

/\/\ac

This works well.

My last BMW 2002 had bad stem seals, could back off the throttle about five seconds and then floor it, the ensuing cloud chased the offending tailgater way back.

Think maybe an oil injection pump from an old two stroke would work well.

 

[Prez]

Took it out for 30 mile flogging session and all is well, no smoke whatsoever. Think the floats may be low now, runs out of fuel with petcock in the run position so I have to run it on the prime setting. Set floats at 24mm as per the clean/rebuild how to, but I am definitely not very proficient at it. Should still be able to spring for a Dyna ignition & some new plug wires & boots as planned, maybe hopefully that'll cure the issue of #3s intermittent staurtup firing issue.

Appreciate the replies, the pics & smoke humor as well. NATEO's "burnout" pic certainly helped me to relax about the situation.

 

[Steve]

you havent smoked out the neighborhood until you have to burn Mystery Oil out of the heads!!!

I am wondering if that might be part of the problem here with Mike's bike. The oil in the sight glass looked a little funny, so we drained it and replaced it with fresh Castrol 20w-50. The oil that we drained had a distinct minty odor to it. I only know of a couple things that smell minty that might be used: Marvel Mystery Oil and Simple Green. I can't imagine why Simple Green would be used inside an engine, leaving only MMO as the suspect.

Normally I would have used 10w-40, but we have a known excessive oil flow issue here, so I went with the thicker stuff. Not knowing how long the bike had been running previously with the smoking issue, I took the pipes off and took them down to the local car wash to clean them out. Got lots of oily water flowing out of them, so I feel a bit better about that.
While the pipes were off, I replaced the drain plug only to find that it would not tighten.

Took another look at the plug and found that it was a replacement, not the original, and had markings on it that said "1/2 T". Not good. It appeared to be a 1/2" oversize plug in a metric hole. I took off the oil pan, cleaned all the sludge out of it, then went to Auto Zone and found a 14mm oversize plug that cut new threads in the hole and sealed up nice and tight. Put the oil pan on, put the pipes back on, filled with new oil and fired it up. Still smokes, but not nearly as much as it did before.

After it had been running for a while, the smoke amount did not change. A friend happened to come by, saw the smoke and offered the use of his compression gauge. Overall, the numbers were not too bad, but they went up considerably 'wet', so it's probably time to check the cylinder bore size, then order rings or pistons to match.