Black Spark Plugs, Black Exhaust!

Hello,
Just got my 82'Maxim 650 running! But, it seems to be running VERY rich. I dont have the brakes installed yet but, in idle it spits out thick/dark exhaust. I pulled the spark plugs and there defintly dark. The picture makes them look wet, but it was more a dryer black coating. Where do I start? Floate height? Mixture screw? Where is the mixture screw on these carbs? Is there on for each? (Im a beginner!) Thanks alot for your help!!!
DG

 

We need some more information on your bike. What kind for intake and exhaust, stock or monified? Looks like there is more to this than a mixture screw adjustment. If you have a stock setup check the air filter to see if it is clogged. Sounds like the bike sat for a while so since you are in there clean the airbox and make sure no critters have made nests in the air intake . The plugs do look a little wet and that may indicate carb problems like float height or stuck carb slides. Choke circuit may also be not closing. If the carbs have not been cleaned its a good idea to do so.
Replace the plugs clean the airfilter and go from there.

 

Before you start doing ANY Tuning.
You need to run a Diagnostic Test.

Compression Test.

Fully Charged Battery
Plugs Out
Compression results for ALL the Cylinders.

 

What Rick said. But to me, that looks like over filled oil. Or tons of blow by.

 

Black exhaust can mean bad things like worn or damaged rings. Thats where the compression test comes in. Do you know how to do a compression test? You'll need a guage. Most will screw into your spark plug hole. Others you have to hold in place. Get the one that screws in.
I argued with a guy once that black smoke can't be from condensation. Water sitting in sooty pipes can cause black smoke and running way rich will cause extremely sooty pipes. Black plugs, rich mixture, black sooty pipes, black condensation, black smoke.
I would lean toward the latter unless your bike is really high in miles or the previous owner was abusive. Definitely do the compression test. If that is good, you probably just have a dirty bike with dirty carbs that need cleaning/rebuilding/tuning. Whatever else is in there will clear itself out.
After a cleaning, run fresh gas and a fuel filter. They are nice to have. Mine has really fine black grit on the intake side and is as clear as a bell on the other side. So even fresh gas has caca in it. Good luck, bud

 

Thanks for the great advice. Before i read it, i adjusted the float height. , it was significantly off. Now the exhaust isnt black on idle. Its only black when at 1/2 to full throttle. Anyways, it sound slike ill need to pick up a compression tester. Whats size will i need? Thanks again for the help!

 

I'm so bad with knowing sizes. I just brought a spark plug with me and got one the same size. Do you know how to do the compression test?

 

http://www.sears.com/shc/s/p_10153_12605_00902171000P

When my MAC Tester blew a hose, ... I got one of these.

 

I believe the one Rick pointed to will work for you bike (it looks like it's for an 18 mm and 14 mm spark plug hole...with a 14mm extension), and your 650 will be a 14 mm. However, might I suggest paying a bit more for one that has more adapters, specifically one for 12 mm plugs, as you may run into another bike, or engine for that matter, that uses a 12 mm plug.

I wish I had paid $10 more when I bought mine, because my gn400 project has a 12mm plug. I made one...but still...it's easier to buy the set. I never found a 14mm to 12 mm adapter in any local stores.

 

I had a compression tester but it was only for 14mm and 18mm plug holes. I took one of my old plugs and took a cutting wheel and cut the rounded portion of the plag that is right above the hex head of the plug. Then I took a peice of wire and removed the white powdery substance from around ceramic of the plug, once I removed the powdery stuff the ceramic pulled right out. I then tapped out the inside with a 14mm 1.25 thread to accomodate the 14 mm thread of the tester. It worked out well. Now I have an adapter for the 12mm thread plugs. I had to do this because I could not find an adapter anywhere without purchasing the entire tester package.
Just a suggestion for anyone who might run into the same problem that I did.