Ktm sx 250 2020 12 hours old jetting problem

MadsDausel
My freind has a sx 250 with 12 hours and the bike is now broken with a 450 mainjet so it need a new cylinder and piston...

He buy a used 300 kit of me and the bike is now running again but it can take all the fuel I give it..

First mainjet was 470 and I think it sounds lean and take a 490 main, 510 , 530 and now 680 but the bike still sounds lean? Reeds are fine. float height is good. And I can't find any leak where it can take false air. Any ideas?

35p
680 main
43-71 needle
AS 1.5
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YZed250
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Costa Mesa, CA US
YZed250 3/2/2020 1:14pm
3/2/2020 1:14pm
Sounds like left side crank seal leaking to me. What about taking it to the dealer? 2020 KTM with only 12 hours ...
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MadsDausel 3/2/2020 1:47pm
3/2/2020 1:47pm
YZed250 wrote:
Sounds like left side crank seal leaking to me. What about taking it to the dealer? 2020 KTM with only 12 hours ...
The dealer say he has run it too lean so they will not cover it.. I try to make a air valve and little pressure in the engine for a time so I can see if it leak air.
sandman768
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Location
Saratoga Springs, NY US
sandman768 3/2/2020 4:26pm
3/2/2020 4:26pm
Could it be the carb jet block oring is bad? I would not have done anything with that bike until a KTM dealer found the problem that caused the lean condition. I run between 450-460 main on deep sand tracks, my bike has 60hrs on original top end & still runs strong.
1

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