My 2016 ktm 50 sx wont idle and is exceptionally worse once hot. top end new, carb thoroughly cleaned reassembled. new plug and tried another used stator air filter new. have not tried reeds yet

Check inline fuel filter ( if you installed one) and the one on the top of the petcock in the tank. Then clean all of the carb and jets too. There is a special wire tool made by companies like k&l for cleaning inside of jets. Usefresh gas to and make sure the premix ratio is correct. Clean air filter while you are at it, and replace spark plug after checking the gap.

carb is running tooo lean, remove carb and strip down, removing all internal jets, check float height setting and note number of turns mixture screw is set at.......completely clean internals in a large can of carb cleaner- available at wall mart- has a basket inside the metal container so you will not loose small parts while the carb is soaking in the mixture...leave for a day, the crean all parts and blow out with high pressure compressed air. and re-assemble, and refit.....please note, never use ethanol fuel in your motorcycle, I only use classic gas in all my vehicles...less problems

If there is a leak in the head gasket it will never run properly. Maybe the carburetor is plugged if it has sat for a while. The gas/oil mixture can go bad over time. The leak could be from a loose gas line. Or possibly even oil dripping from the oil filter if you just cleaned and re-oiled it.

ITS THE CARB!!! -- take it to a qualified professional and have them clean and set the carburetor!! If you put the power valve in wrong, they can fix it too!!

your pilot circut is clogged. Take out your pilot jet (this is the jet closest to the cylinder) Be sure to spray carburator cleaner thru this jet until the stream is heavy and solid. Next insert the tube from your can of carb cleaner into the hole the jet was in and spray until it comes out in two locations in the carburator. One in the throat of the carb and one directly under the front edge of the slide. Go to the back of the carburator and you'll see a couple of holes at the bottom edge of the carb that mounts to the air box. these are vent holes. Spray cleaner into them and find the hole that vents the pilot circuit and insure it is not clogged. Once all of these are cleaned your bike should run as if new. Good Luck.

Thank you for contacting FixYa with your inquiry. I have been going over some of the older help requests that have been archived and
trying to provide solutions for those that didn't get answered. Hope
this information helps.

Try these:

KTM Owners Manual

Start here

http://www.carlsalter.com/motorcycle-manuals.asp

http://www.ktmusa.com/download.php?dataID=8101G9_OM_EN.pdf

KTM Service Manual

http://www.ktmcyclehutt.com/ktm-parts/ktm-parts-search.php?ktm-motorcycle-parts=Repair-Manuals&year=2007&ktm-model=sxf-450&fitment=bigbikes-all

KTM Repair Manuals Order Site

http://www.repairmanual.com/KTM.html

http://www.tryvod.com/search/ktm-2008-450-xcf-owners-manual-download.html

http://www.pdf-manual.com/user-guide-instruction-owner-manual-ktm-450-exc-2008-17793.html

http://www.pdf-manual.com/telechargement2.php?id=17793

http://www.mydrive.ch/browse#/

Manuals General:

http://www.dansmc.com/shopmanual2.htm

Other Manuals Sites:

http://www.fixya.com/motorcycles/ktm

you shorted the wires

Look into your power valve. If it doesn't operate freely, you won't get peak performance. They can get gummed up.