79 special smoking

[cokeman]

Bike starts and runs strong. Problem is that after a few minutes it starts to smoke bad from the left hand exhaust. When I first start it everything is good, no smoke at all. After it runs for a few minutes smoke billows from the left exhaust, Nothing from the right which I find strange. I can shut it down and wait for it to cool off and restart and again no smoke untill it warms up. I had the pipes off for 2 weeks standing on end so I don't think they are full of oil. Although there appears to be some oil collecting at the rear of the pipe. PO tried unsuccesfully to remove the baffles, Just left a big gaping hole on the ends of the mufflers.

A little history may help. I bought it from not running. PO said that it smoked black. No wonder the carbs were full of varnish and dirt. Also when I drained the oil to change it out came 7+ liters of clean oil, NO gas/oil mix, I know what that looks like from previous experiance with an XJ! Oil looked like it was just put in. Imagine my suprise.

Now, so far I have cleaned and reinstalled the carbs, rebuilt the petcocks, changed all the fluids. It seems to be running a little rich although no more black smoke, just blue from the left pipe. It is firing on all 4 and the plugs are not wet with either oil or gas. Just a little black from rich mixture.

Any thoughts? All suggestions will be considered. Thanks in advance for your ideas.

Darrell

[egsols]

Have you done a compression test on it yet?

[dbeardslee]

Coke - Blue smoke be a sign of oil burning. Probably a bad valve seal, or could be rings. How do your plugs look? Black and oily?

I'd do what egsols suggested and do a compression test. That'll tell you how your valves are seating. I redid my head several months ago, lapped the valves and replaced the stem seals. Couldn't believe the difference it made. Lots of bolts to turn, but all in all a pretty straight-forward operation.

[mitch]

How long

How long has it run , put 500 miles on it and see if it stops , could be just a stuck oil ring from sitting. keep checking the oil and run it a bit it might just clear up . A lot of bikes here have done just that. If it doesent then it might need rings or valve seals.
Doug

[cokeman]

I did a compression check today. All 4 were 150+. Seems a bit high but they were all the same. Did check with warm engine and WOT. Just for giggles I did the comp check again with closed throttle. Much different results. All were the same but down aroung 120. Strange thing is the plugs are black but no heavy soot buildup. Maybe I am trying to make a mountain out of nothing?

Darrell

[randy]

I had that problem for my first year with Swamp Thing,it didn't clear up by itself,so I changed the valve seals and the exhaust is clear now.

[TopCatGr58]

Hey Darrell,

Like Mitch said, run it at full operating temps for a few hundred miles. Also put some SeaFoam in the gas. Shame you already changed the oil, cause you could have put in some MMO into it and run it on centerstand, NO LOAD for about 5 minutes or so, and then drained and refilled, it can help unlock stuck rings, and removes varnish from engine parts really well!!

Hate to ask, but what TYPE of oil?? Full Synth can leak past rings and such easier than Dino, and can lead to clutch slippage! I don't want to start an OIL THREAD , a search will reveal lots of info, both in the tech tips, and in the Posting FORUMS.

The 150 PSI could be a little high due to excessive carbon buildup in the cylinders/head and running it for a while with the SeaFoam can help to remove it. Watch your plugs closely. Is the crankcase vent tube clear, not plugged??
T.C.

[cokeman]

TC/ ALL

I am using Casrol 20/50. Vent line is clear, I have PODS on right now so vent is not hooked up. I do have a filter on it though.

I haven't found either MMO or seafoam on the shelves of stores that I frequent. Where do I buy this stuff in Canada.

Would putting a little MMO in the cylinders help with carbon build up? Any other Ideas along that line? I will put some MMO in the oil providing I can find it, and run it for a while then change the oil again. If it works it may be a cheap fix.

Right now I am thinking that valve seals are probably the culprit. Allowing oil to leak into the pipes while it sits then burns it when the pipes get hot, Kinda make sence to me. Although I have absoultely no Idea how to change the seals I am sure I can figure it out.

Thanks for the responce so far

Darrell

[Rasputin]

I am not sure about MMO in Alberta, but I used to be able to get it from oilfield supply stores. Check around your area for a rig supply shop (maybe Yellow pages). As for Seafoam I have found my local Napa has it in stock and someone told me that Walmart is stocking it now.

[egsols]

Originally posted by cokeman

All 4 were 150+. Seems a bit high but they were all the same. Did check with warm engine and WOT. Just for giggles I did the comp check again with closed throttle. Much different results. All were the same but down aroung 120.

That's normal, same thing happened on mine. Same numbers basically 155-165 warm, 120 across the board without throttle open.
Problem was I did the 120 first and got worried, then I remembered I need the WOT. It helps to have something to compress.

[planedick]

7 + liters?

I hope you didn't put 7 liters of oil in the bike. If you did that would be the reason for the smoke. 3 liters is what is needed. Sounds like the PO put in oil to the line on the sight guage while it was on the side stand. Check oil level while on the center stand only.

[dbeardslee]

Planedick - GOOD CATCH! I'm glad one of us was paying attention

[cokeman]

NO, I didn't put 7 liters of oil in the bike. Thats what I drained out of it when I went to change the oil and filter.

Anyway, I have found Seafoam at NAPA. MMO is another issue. Seems most people have heard of it but no one carries it in Lethbridge. I think I will treat the oil with seafoam and then change it. Then I will add some to the gas and run the bike for a while. I really don't want to pull the heads but it may come to that to change the valve seals. Just seems strange that the bike does not smoke until it's warmed up. You would think that if it was a stuck ring that it would start smoking right away.

One more thing, Can a guy put a little seafoam directly in the cylinders and let it sit to try to remove some of the carbon buildup? If not, any other suggestions?

Anyway, again thanks for the suggestions so far.

Darrell

[egsols]

Hey cokeman,

For engine cleaning they state to pour a small amount through intake, however, I found this on their site......


"For Engine Storage
For storage, the engine should be thoroughly saturated internally with Sea Foam. Sea Foam can be injected internally through the spark plug holes or through the carburetor with ignition off. "

[dbeardslee]

Coke - don't put a load on it with seafoam in the crankcase. Just let it idle for twenty minutes or so, and then drain it out. It REALLY thins out the oil, and rumor has it you can spin a bearing that way. I put some in mine and ran it 200 miles that way. Didn't do any damage, but man did it get the internals clean - too clean. There was some ancient crud that was sealing my head gasket and the seafoam cleaned it out of there - hence the head job.

Mine always smokes out of the breather filter once it's warmed up. Never noticed it with the stock airbox, but with the pods it became immediately apparent. I'm not burning very much oil, and I've checked the engine temp and all is well, so I figure it just does that.

To decarbon the heads I've heard that spritzing water directly into the intake on the carbs will get it out, but I haven't tried it yet as my head is pretty much spotless after going through it. Don't know how well it will get the carbon off the valve stems though. In my mind doing this stuff as opposed to taking it apart and really fixing it is about like using ambasol instead of going to the dentist - but that's just me.