Smokin' Question

[Cobia]

My, new to me, '79F is smoking out the exhaust... not profusely but enough to make it noticeable. Now, carb #2 had a stuck float and it just spewed fuel out the left exhaust. So, after re-doing the carbs, on Tuesday we took it out for a 180 mile spin and it ran very strong and without hesitations (thanks to Phil's excellent float and other adjustments). Smoke wasn't very apparent to Phil or I during the ride but when I got back I noticed several things:

1. All plugs were light tan color except #1 which was black but not oily/sooty
2. It had consumed about a quart of oil during the ride.
3. When I started it up after the second day it smoked profusely for a while and then settled down to barely noticeable
4. Closed the crankcase breather hose with a pair of needlenose vice grips and had no smoke in the crankcase

Did a compression test and found the following results:
#1 = 168 psi
#2 = 172 psi
#3 = 180 psi
#4 = 150 psi

Considering I had no smoke in the crankcase, which might indicate no blow-by from the rings, could this be an indication of bad valve seals?

Any and all input is greatly appreciated.

BTW - It's coming together quite nicely otherwise.

[tarzan]

With your compression readings it looks like you may have some rings carboned up,the high readings could indicate that .You might try putting some seafoam in the cylinders and let it sit for a day or two and then run a little seafom in your gas for a tankful of gas.Sometimes people dont ride em hard enough and they load up.PO's hmm.
Alot of times just running them will clear things up.

[Cobia]

I did put about 1/2 pint in the 1st tankfull but have not put any in the cylinders per se. I also put about a couple of oz. in the crankcase before the ride. I think I will try that and let them soak up for a few days. Should I use the spray or just pour some of the liquid in there?

[Ivan]

Smoking after sitting overnight and then tapering off to nothing is a classic sign of valve seals.

Hard to say which ones, most of the time they all get replaced. On a old school chevy V8, you could do it without removing the heads, by putting compressed air in the cylinder to hold the valves closed while the spring was pulled. Since the springs are recessed in the head on the XS11, I am not sure how you would compress the springs to do it this way. Maybe someone has an idea.

[Cobia]

Ivan,
That's what I'm hoping for, someone's idea on how to do that w/out pulling the head off. I rode it pretty hard, 75 to 90 mph, on that 180 mile ride so.... I think I could have burned off a lot of carbon in the process.

[Ivan]

Around here there is a company that is called BG.

They make some stuff called 44k, and is made to put in the fuel. It works quite well, and after running a can of it through a car, it will take all the carbon out of where ever the fuel touches. I put it in my old impala with 125k on it, and the car started smoking afterward, since the stuff cleaned out all the coke (carbon deposits) from the oil rings and they didn't seal after that. When I tore into the motor, the heads and cylinders looked like they had never seen a hint of carbon. I have been contemplating using some in my XS, just for giggles.

You might try some of that, if it is available in your area. I think it is made in Wichita, but I am not sure.

[bikerphil]

Good thread about oil smokin'....

http://www.xs11.com/forum/showthread...+removing+head

Hey Robert, mabye the oil is thinned out some too. We never changed the filter after the gas in the oil problem. I forgot, did we put 20W50 in there?

[Cobia]

Phil,
We didn't change the filter, we did put in Castrol 20W 50, and added 2+ oz. of Seafoam before going out on the ride. So, for sure the oil was somewhat thinner than even straight 20W 50. Could that be what's causing the valve seal leak?

[bikerphil]

I don't know for sure. If you've got a filter, mabye change it and the oil, see if that helps. That thread I posted above mentions some tool for compressing the valve springs somehow with the head still on. It was pretty vague and didn't really explain it. Myself, I don't see how this is even possible. I'd try an oil and filter change first. A filter and some cheap a ss 20W50 from Advanced cr ap auto parts can't cost much more than $15.

[Cobia]

That sounds like a good 1st step probably do it Monday, thin oil can get through many a seal. I don't think we "Dicked" the carbs. Too many under our belts by now!!

I liked Prom's reply to the guy who said he got good info from a seasoned mechanic:
"I can't call myself a seasoned mechanic..."

I'm more like a marinated one.
Good job, Jurgen."

LMAO!!!!

[bikerphil]

Yep, that was definitely blue smoke coming out, not black.

[tarzan]

From what I've read ,I dont think you are suppose to run seafoam in the oil very long.I agree a filter and oil change is a good thing,but I still would try the seafoam in the cyl overnight thing, then the oil change. That might soak in and loosen any carbon compacted in the ring groooves and between the rings.JAT

[79XS11F]

Just how common is this carbon fowled rings thingee anyway? I have torn 3 of these engines apart over the last few years and have not yet seen any carbon fowled rings or even any carbon in the ring areas at all. I have seen Hugh amounts of carbon on the tops of the pistons and in the combustion chambers of these same engines but no issues with the rings. It would seem to me that if there's enough carbon in the rings to stop them from floating and sealing to the walls, they must not have been sealing very well before they became fowled. The fowling being caused by blow by. If this is the case then it's time for new standard size rings and a light hone of the cylinders as a minimum repair. A cold compression test both dry and then with oil added followed by a hot compression test both dry and with oil added will tell you a lot about whats going on inside the engine. If you get a big difference between the cold dry and wet test then the rings are likely toast. There would also be a big difference between the cold numbers and the hot numbers but not much difference between the cold wet numbers and the hot dry numbers. If when it's all said and done, a ring job is not going to happen .. then accept that the engine will burn oil and keep an eye on the oil level. Cleaning the carbon out of the rings may even result in more oil consumption because the carbon that was helping seal the pistons to the walls will have been removed.
That's my 2 cents.

[renegade_xs11g]

One other thing to try...

Marvel Mystery Oil...

I used it to unseize the motor in the saturn, SWMBO car, she says it's running better than it has in a long time...go figure, run it out of oil, seize the motor, unseize the motor and it runs better

BTW it has 211,000 miles on it, she's put 100,000 of them on it herself

maybe 1/2 oz or so in each cylinder...let soak for a couple of days

BE WARNED THO, when you start the motor, it will SMOKE like mad, but it'll go away after a few minutes

[Larrym]

Exhaust valve stem/seal

Had similar situation with my special: Not only smoked at start-up but doused enough oil into the exhaust to have it drip/splatter out the muffler. Always cleared up after warming up and plugs showed similar as yours. Engine had 14.5 K miles on it but had sat for years.

Did the "put transmission fluid in the cylinder and let it sit for a while" fix but still had occasional smoke/oil out exhaust at start-up.

When I swapped out my original exhaust for the factory headers/JC whitney slip-on mufflers I looked at the exhaust valves. Sure enough, I had one exhaust valve stem which was coated with baked on goo. I shot it with penetrant while it was in the open position and hoped for the best. Haven't had a true "smoke-out" event since but then I haven't put the miles on the bike to really know for sure if the exhaust valve seal is a "goner."

If exhaust valve seal really is bad then valve stem will have to be de-gooed as well for new seal to do its job. I don't want to pull the head for one leaky exhaust valve seal either but then again if mine starts using oil like a two-stroke .....