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Rebuilt Carbs / Smoke From Exhaust

  • Thread starter Thread starter Vrian_Sinth
  • Start date Start date
V

Vrian_Sinth

Guest
So I have a 1980 GS550L that I've had for well over a decade. It's been an awesome bike. After a move, the bike sat for about 1 1/2 years on the side kickstand. The carbs on the lower end of the kickstand tilt went bad (ethanol) and I ended up rebuilding all four carbs. I feel bad I neglected the bike for so long.

Now that the fuel system is running like a charm, I've discovered that it smokes. It is burning oil from the same cylinders on the kickstand side. What's odd is that it never burned any oil and now it is...and a lot.

Any ideas on what may have gone bad? I'm thinking valve stem seals. I was hoping I wouldn't have to tear into the cylinder head, but it's looking like I might have to. Any thoughts or ideas on the matter are appreciated. Thank you!
 
I heard about possible problems from long periods on the side stand and started using a brick (I have no center stand). I also decided it looks better on a brick.

image.jpg

I have no technical info to help you with, but I have extra bricks. Even envelopes they'll fit. But the Post Office has these scales...
 
How much has it been run since bringing it back to life? :-k

Yes, valve seals are a likely culprit, but there are other possibilities, too. The surface of the cylinder liners might have rusted a bit. With some use, the rings might polish the rust off, if it wasn't too deep. Another possibility is that the rings are stuck. A few hundred miles at "elevated" RPM with some fresh oil would help that.

Bottom line, if some enthusiastic riding does not 'fix' the smoking, it's time for valve seal replacement.
When you get into replacing seals and gaskets, OEM Suzuki gaskets are HIGHLY recommended.

.
 
The piston rings and your cylinder are both ferrous -- moisture or acid etch can cause a rust ring that may have pitted the sealing surface. This is another possibility causing this smoking issue

old oil and condensation are the enemy to cast iron and steel and aluminum -yada yada yada --
 
It's probably only been run 10-15 minutes since being brought back to life. I'll try to let it run a little longer. I'm really hoping I don't have to tear into this thing right now.
 
I should also mention it doesn't immediately start smoking. It's fine for about the first minute or two, then the smoke starts up.
 
If it doesn't smoke right away, it's likely NOT the valve seals. :encouragement:

Get it ready for the road, then ride it like you stole it.

.
 
Are you sure it is oil? Is it white smoke? I have experienced a carb rebuild produce a white fog with too much fuel.
 
TowPilot said:
Are you sure it is oil? Is it white smoke? I have experienced a carb rebuild produce a white fog with too much fuel.
Click to expand...

Before I rebuilt the carb, fuel was literally spraying out the exhaust. I could smell it, along with white smoke.

Now the carbs aren't overflowing at all, but they could probably be tuned.

The smoke starts after 3-4 minutes and only out of the kickstand side exhaust. When the smoke gets thick, it starts lightly coming out of the other exhaust (probably leaking through the cross tube).

It isn't blue like I'm used to seeing out of a car, and obviously it isn't coolant, but it doesn't smell like fuel. I just figured it's burning oil.

I'm also seeing small droplets of oil coming out of the exhaust joint where the chrome exhaust guards screw in.

So if it is a seized ring, or a pitted cylinder, high revs might free up the ring or grind off rust? How high should I get the RPMs? Is there a solvent I should put in the crank case that might help?

Worst case, are these bikes hard to re-ring and bore out?

Thanks so much for all the feedback!
 
Quite possibly stuck (gummed) ring packs.
Mine was carelessly laid up for a decade - never bothered storing it properly as I intended to use it again, but you know how that goes.
Anyway, when I eventually got around to putting it back on the road, it was obvious that the rings on a couple of cylinders were a bit stuck. It was running sort-of ok, but wasn't right. Over the next few months I gave it various treatments down the bores to try and unstick the rings, with some degree of success. I'd leave the cylinders with a couple spoonfuls of diesel, ATF, etc overnight or even for a few days at a time. I even bought some super-dooper ring-unsticker and tried that.
Not sure what worked in the end, but eventually things slowly came almost right.
However, when I had no choice but to strip the barrels off to remedy a chronic oil leak I discovered that rings on cylinders 2 and 3 were still a bit stuck, so all these fancy treatments didn't do the full job. The rebuild took ages and when I removed the pistons I left them, complete with rings, in a bath of paint thinners (mostly acetone, xylene and other good stuff) and ATF, which by the time I got around to completing the rebuild had totally softened and disolved the gummy deposits that were causing the sticking, so that the old rings were really easy to remove with no danger of breaking them.
So, there ya go. If I had another engine with stuck rings, I'd drench the cylinders with paint thinners and ATF and simply leave them for a loooooong time.
I know that doesn't help you much, but it shows how resistant stuck / gummy rings are to being treated in-situ.
 
Grimly said:
Quite possibly stuck (gummed) ring packs.
Mine was carelessly laid up for a decade - never bothered storing it properly as I intended to use it again, but you know how that goes.
Anyway, when I eventually got around to putting it back on the road, it was obvious that the rings on a couple of cylinders were a bit stuck. It was running sort-of ok, but wasn't right. Over the next few months I gave it various treatments down the bores to try and unstick the rings, with some degree of success. I'd leave the cylinders with a couple spoonfuls of diesel, ATF, etc overnight or even for a few days at a time. I even bought some super-dooper ring-unsticker and tried that.
Not sure what worked in the end, but eventually things slowly came almost right.
However, when I had no choice but to strip the barrels off to remedy a chronic oil leak I discovered that rings on cylinders 2 and 3 were still a bit stuck, so all these fancy treatments didn't do the full job. The rebuild took ages and when I removed the pistons I left them, complete with rings, in a bath of paint thinners (mostly acetone, xylene and other good stuff) and ATF, which by the time I got around to completing the rebuild had totally softened and disolved the gummy deposits that were causing the sticking, so that the old rings were really easy to remove with no danger of breaking them.
So, there ya go. If I had another engine with stuck rings, I'd drench the cylinders with paint thinners and ATF and simply leave them for a loooooong time.
I know that doesn't help you much, but it shows how resistant stuck / gummy rings are to being treated in-situ.
Click to expand...

Thanks for the comment. That helps paint a much better picture as to what I might be dealing with.
 
Are you sure the white smoke isn't steam.

In the damp climate of the UK, I literally have steam and water dripping out of mine. But it takes the exhausts and mufflers at least 10 minutes to heat up enough to evapourate it. Also why they always rot from the inside out.
 
londonboards said:
Are you sure the white smoke isn't steam.

In the damp climate of the UK, I literally have steam and water dripping out of mine. But it takes the exhausts and mufflers at least 10 minutes to heat up enough to evapourate it. Also why they always rot from the inside out.
Click to expand...

Thanks for the advice. I live in a desert, so the humidity probably isn't an issue.
 
Could be. I will be changing the oil again soon. I think the rings in cylinder 1 (closet to kick stand) are fouled up or stuck. I did a little research and ended up pulling the spark plugs on the two left cylinders. I put an equal mixture of acetone, marvel mystery oil and atf fluid in each cylinder. I'm going to let it sit a few days, change the oil and try again. Fingers crossed. A lot of people swear by this concoction, or similar ones. Cylinder one drains slowly, cylinder two isn't draining at all.
 
Steve said:
You would be surprised how much moisture there is in the rather incomplete combustion inherent in a cold internal combustion engine.

.
Click to expand...

As an approximation, a gallon of hydrocarbon fuel will release a gallon of water on combustion.
 
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