need help!!spark plug is black....

That means that are running rich

Remove de slide of carb, and put the c-clip one notch upper, to decrease teh ammount of fuel to the same ammount of air

I'm on my first build having the same problem..
I tried these mixes in this order since building my bike 2 weeks ago and it resulted in a black oily plug..

16:1,
moved e-clip up one notch and changed to 24:1
moved e-clip down one notch from the stock middle position at 34:1

all three times the engine has started up good and easy on the new plugs (ngk bp6hs) running best on the 24:1, 34:1 mixes but after a ride and stop or two on all 3 mixes I would be soon stranded with a fouled plug or a bogged out motor that wouldn't start or fire. The plug has been oily and black all 3 times.. I think i'm not moving the carb e-clip on the needle around right..any help ?

tomorrow i'm going to to try 40:1 at 1 notch above stock position on the carb needle..

it will start and run for sure.. but will run once i park it a bit? ha *crosses fingers*

Ballpark setup for the average motor is usually 32:1 with a quality non-synthetic oil and the clip on the second notch down from the top (top being not the pointy end) & remember to always recheck plug color - it knows far better what your particular engine needs than we do lol

Also, the leaner your mix (gas to oil) the richer it becomes (air to fuel).

Run 32:1 and then start playing with the C clip. Move it up two notches and see what you get, just remember to check the plug.

How do you know if it is synthetic 2 cycle oil or not? I have bought two different brands of 2 cycle oil and neither one states if it is or is not synthetic.

If it doesn't say "synthetic" on the bottle - it's not, they'd not miss an opportunity to advertise

I have a similar question. I have a SBP expansion chamber on my gt5 and when I looked at the plug today after a ride it was black, almost burnt looking. It is the stock plug and I already have moved the clip to the top setting. Also around the exhaust gasket it is slightly leaking black sludge. What is causing this? is my exhaust restricted?

What's your oil:fuel ratio? If your running the suggested 16:1 that's waaaaay too much oil. I can see using that ratio with the crap-based oil elsewhere in the world, not many countries have the same oil standards that we and other advanced countries have. 24:1 for the break-in period then 32-40:1 with a good synthetic. Find an oil brand you can get all the time, it's generally considered not good to change oils. The big oil companies all have a synthetic 2 stroke oil so that's not a real problem. Heck, if the large department stores in your area have a chainsaw section, like Fred Meyers does, then you can get Poulan, Husqvarna, Stil and other chainsaw motor oil. Look at the lable for an oil thats formulated for air-cooled motors. They run hotter than water-cooled motors and need a different formulation. That's why I suggest chainsaw oil, if you can get the same stuff all the time.

For a broke-in motor some here are using OPTI 100 which is mixed at up to 100:1, a little thin for this old racer. I ran Super Kart and the saying was if you didn't leave at least a thin stream of smoke there wasn't enough oil in your mix.

Adding to this, junk the stock plug. God only knows the heat range on that thing in reality. Cold weather I use a B5HS, hot a B6HS NGK plug. Do not get a BP5HS or BP6HS NGK plug. Sometimes the extended tip plugs can be closed by contact with the piston.