2005 ktm 125 sx top end bog?

2005 ktm 125 sx top end bog?

Posted in the KTM Motorcycle Forum


Salmon Arm, Canada

#1 Apr 3, 2007
here's the deal: i recently replaced the piston in my 125 and it had next to no power. we then took out the main jet wich was a 190 and put in a 185. this gave the bike a bit more mid power but the top end still sucked. we now put in a 180 main jet and it runs crisper, but still isn't riding like it should. it is almost impossible to get the front wheel up, where before it was going up everytime you shifted gears. The power valve is clean. any ideas???

Strathfield, Australia

#2 Jun 19, 2007
maby put all stock parts again and i would get it looked over by a mechienic

Normal, IL

#3 Feb 9, 2009
WOW! a 190?? i have a 172 and it still runs rich. how much compression dose it have? b/c you might have a ring stuck. did you re bore your cylinder? are your reeds worn? if they are turn them upside down. it works. bleed your clutch.com pletely clean out the carb.
john macleod

Calgary, Canada

#4 Feb 14, 2009
you have definitely compromised your powervalve system or haven't cleaned your air filter. if u take off the left side.. ignition side tiny breather cover on the cylinder ( it has a breather hose connected to it) and rev the bike u should see the powervalve arm move up and down between 2 marks about an inch apart in the cylinder if the system is operating correctly. if thats not the case... refer to assembly manual. hope u didn't take off the exhaust flange and boggle the 3 powervalves timing. the marks are so tiny u almost can't see them.


#5 Aug 2, 2010
yeahhhh how do you take the front wheel off a ktm 125 sx 05?? hahah

Midvale, UT

#6 Feb 25, 2011
kirkkkk wrote:
yeahhhh how do you take the front wheel off a ktm 125 sx 05?? hahah
are you serious!? You don't know how to take the front wheel off? You shouln't be trying to figure out how to diagnose top end bog if you cant even take the front wheel off! haha lol :)

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