What could cause a KTM 250SX transmission to

float levej wrong or blocked jets

All being as it should it is either ignition or fuel problem. Check air filter is clean or take for run without to see difference. Do a hard cut to check spark plug reading for lean out or fouling (run engine open throttle until high revs snd cut ignition while closing throttle and pulling clutch in to stop engine. Check plug lead. Change plug. Ignition grounded. All the basics

Is this a genuine part if not the part may be at fault also if not is there any dirt through the hole in the crank case the gear shaft goes through a simple solution is to use a multi tool and sand the shaft or crank case hole

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

Try these:

KTM Owners Manual

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

Take it to a shop. If you have to ask, you dont need to be working on it.

It sounds like the end of the shifting shaft has broke loose, it is a welded joint, If you can grab the shifter with your hand and feel that thing slip in there, up and down,that might be the problem, but splitting that case, ugh, total rebuild.Too bad you can't get to it through the clutch. Hope this helps.

Check the post you submitted yesterday. There are a couple solutions listed for this issue.

Correct me if I'm wrong but the 250SX is a 2 Stroke engine with a Gas (1.98 Gals Unleaded Premium 91 octane Recommended) to Oil Mixture (using Motorex Cross Power 2T at a 40:1 - 60:1 depends on oil quality) and when KTM says to Change the transmission oil the amount called for is 0.7 liters engine oil using Motorex Top Speed 4T 15W50. These Quanities are from an 04 250SX could not find a 2000. So consult with your local KTM Dealer's Service Department and pickup a Owners Manual at the same time it would be in your best interest. Liter breakdown 0.7 liters = 0.739681 quart (US liquid) OR 0 quart (US liquid) and 1.47936 pt (US Liquid) / 0.7 liters = 1.47936 pt (US Liquid) OR 1 pt (US Liquid) and 0.958726 cups (US)