Motorcycle Repair: TTR90 excelleration, needle jet, factory stock

Question
We just purchased a used 03 TTR90 it starts and runs good to about 3/4 throttle.  From 3/4 to full throttle it cuts out and puffs black smoke out of the muffler.  I thought the air cleaner had too much oil on it so I re-cleaned it and oiled it again and had no change.  I then removed the air filter and housing and the engine will go to full throttle and not cut out or make black smoke but, gas shoots out of the carb even if I hold the foam air cleaner up to the carb it will start to cut out and puff black smoke.  The air cleaner also gets gasy.  It has the factory stock main jet and idle jet in it.  What else should I look at to fix problem.

JW

Answer
Assuming your carb is clean,

Sounds like you're rich on your needle jet.  Raise the clip (to lower (lean) the needle), try this one position and ride, then again if it doesn't do it.  If you can not get it adjusted - run the bike at full throttle then kill it with the kill switch,keeping the throttle wide open until the bike comes to a stop.  pull the plug and check the color, if it's black try going one smaller on the main jet and back to original position on the needle.

Jetting is a tough game but once it's done, it's usually done.  Here is a helpful site

http://www.mudbog.net/basic-carburetor-jetting.html

Anthony
'Ride Today - Live Again'