Oh Dear!
I've been trying to get enough wood put up for winter and our internet has been spotty at best. Sorry
Chris... Thank you for jumping in KWhack,
The 70 will use the oil for the engine lubrication as well as the tranny to the best of my knowledge.
It is important to keep the level up! Honda's generally have you hold the dipstick in the opening and check the level as opposed to screwing in the dipstick, and removing it and then checking the level.
There should be hash marks (they look like window screen on the dipstick. you need to keep the oil in those hash marks. The engine and tranny are counting on you!
The black "soot like " stuff is carbon and oil fumes in your intake boot. Most likely the crankcase vent and valve cover is hooked up to the intake to draw the fumes in the engine and burn them instead of just venting to atmosphere and having oil collect and drip on the ground.
Any gases or oil leaking by the valve guides or possibly the rings will carry/collect some oil, when the gas cools the oil condenses (like water vapor) by running the lines to the intake the idea is to burn them before they collect and drip.
[I was riding it and the engine was hot and you put it into neutral and it would idle for a little then just shut off...I tried the idle screw and it didnt work/quote]
Since it's so much cooler now than summer the jetting is "off"
If you haven't messed with the timing most likely the engine is running too lean and needs more fuel.
You may be able to open the fuel screw and get the bike to run better.
Since the 70 is a fourstroke it has a fuel screw, the two strokes have an air screw.
The fuel screw is just as the name implies, adjusts the amount of fuel in the engine for the slow circuit (known as the pilot in two strokes)
Look at the carb, the fuel screw will usually be on the bottomof the carb body on the engine side of the carb.
http://www.thumperfaq.com/fuel_screw.htm