Ktm 250sx 03 shifter shaft sticking

is the gear leaver returning to position after trying to select a gear.it could be that the shaft from the leaver is bent or the drum is stuck or return spring is broken.

How is your clutch? Does it slip or drag when starting out? When you put it into 1st gear when starting out does the bike lunge forward? Hold it in first gear with the clutch in and rev the bike up. See if the bike wants to move forward with the clutch in.It sounds to me like your clutch isn't set right or getting worn out. Much easier to shift at low rpms on a clutch than high rpms. I hope this helps...

Either the shift linkage could be binding or you may need to adjust the clutch.
The other problem might be a synchronizer in the transmission going bad.

not sure bout the 4 strokes but my 250sx has got a level plug around the water pump. have a look there

not sure bout that bike specificaly, probly there is a spring on the gearshift shaft , or something to return the lever and shift drum back whenever actuated. no matter what it is, you gotta split the cases to fix 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.

this sounds like the selector fork has broken inside the gear box so its a strip down to sort this one out

You will want to remove the cover then use a light plastic hammer and a small punch to remove the seal. It should come out very easy. Install the new seal evenly.

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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)