2002 Cr 80 black oil

The black stuff to which you refer would be spooge and is commonly caused by jetting that is to rich :) If you know nothing of how to jet a bike you would prolly want to make friends with one who does ;)

Check this link..http://ericgorr.com/twostktech/carbtuning.html for some very good reading on the subject

If you are not riding the bike pretty hard and keepig it cleaned out, this will happen no matter what. My 10 yr old son putts around on a yz80 that is jetted quite well for altitude, lots a splooge, he just doesn't open the throttle much. It cleans off easily and dad has an excuse to hop on an "clean her out a little".

It may be a good idea too go buy a owners manual and go from there.. Alot can be learned from the manual..
Hope this helps you,
Rick

you also may need to re-pack your silencer and replace the seals and springs on your pipe.

My son raced a '99 CR80 last year and teh jetting is perfect. He just moved up to a 125 so my daughter decided she wanted to ride the CR. We never saw any spooge until she started riding. Everything stayed the same except the rider. My son rode at 75 - 100% throttle all of the time. My daughter rides at 25 - 50 % throttle. At that RPM, the engine never heats up enough to burn all of the fuel. It has to go somewhere, so the exhaust is the place. You can try leaning the carb a little (this is NOT an oil ratio problem) but if you get it lean enough so that you have no spooge in the middle, you will be way too lean on top. That could cause the engine to sieze. If you are running too rich (again air to fuel ratio: not oil to gas) the engine will make a kind of blubbering sound. Too lean will cause the engine respose to be sluggish and flat.

Most of the time, the spooge is caused by the engine not running in it's optimum RPM range, and not jetting problem.

about the leak out of the pipe where it meats the engine. Just had that problem with my bike. Replaced the o-rings and its great!

The spooge coming from your buke is common on all CR 80's. YZracer53 hit the nail on the head. Ride it like you stole it. It is meant to be revved.

First two stroke eh. That stuff is spooge. It is normal. If it is really bad you should repack your silencer.