ktm noob needs help...please

i am relatively new to the do it yourself mechanics on my 09 ktm 125sx.  I went on a vaction and my bike sat for about two months.

before i left i made sure to run the carb dry and not leave any gas in it.  When i came back and was ready start the bike she fired up first kick.  I have a fresh spark plug, clean carb (took apart the float chamber to inspect), and a fresh oil change in the gearbox.  She sounded great, idled great but when it was time to go for a cruise she was all talk no walk.  the engine would scream but i would barely get going.  Even after she was all warm still never got going like i've been used to. had to constantly rev just to keep on creeping a long.

Now I am basically stuck and I dont know where to take it from here. 


Can anyone tell me what i should be looking for or trying to do next?  possible clutch problem? resevoir seems to be full.  Could  I have missed somthing when inspecting the carb? All advice is greatley appreciated.


thank you

My guess is your clutch plates are stuck together, might have to pull them and check..

if the bikes in gear and the engine is screaming and you're barely moving then you need a new clutch.

Thanks poldies and pmxhillbilly....this sounds very probable. When I Get some time in the next few days I am going to open the clutch up...are there any tips/things too look for when inspecting and taking the clutch apart in order to confirm either of those issues? This'll be the first time I take it apart anything I should be aware/very cautious of doing other than the obvIous lIke dont mIsplace parts ect..lol...?

....just another follow up question/comment..during my ride I was able to shift up and down through gears..is this still possible to do with possibly stuck plates/or blown clutch? I did not hear any gears grinding

You would not hear grinding gears with a slipping clutch and yes, you'd still be able to shift. Just lack of power to the ground in any gear. If it only revs but won't go in one gear but the others are normal you have a different problem.

If your cheap like me, youd just ride it a couple more times hopeing to get the plates soaked again with oil. Id start with fresh oil too.

Def have the problem narrowed down to the clutch going to try and open it up later today

Opened the clutch case....squeezed the lever before taking out the clutch plates to see how it was functioning...the only part that moved was the most outer pressure plate....all the other ones stayed stuck together... took out the clutch and pressure plates....soaked them in fresh motorex 15-50 oil....put em back in...still the only part that moved when I squeeze the lever was the most outer pressure plate.....the clutch plates had almost zero wear...saw what seemed to be grooves on the clutch basket but when I felt for an y texture the metal was flat...


It's normal for only the outermost plate to move when you pull the clutch lever. In order for the others to move and all separate there would need to be a spring between each one. This is "static drag" (at least in the Caterpillar transmission world) and is the reason it is so much easier to push your bike in neutral than in gear with the clutch in.

RIght on superslo....If thats the case then I guess the plates must be cherry...mInImul wear. RIght amount of oIl....movement from the outer preasure plate when pullIng clutch....messed around w the the bIke whIle It was off and also whIle runnIng...notIced I could roll It around the yard In gear w/o havIng to squeez the clutch lever and w minimal resistance...(when running and in gear it basIcally goes nowhere unless revving hard)

I guess that would just indicate further that I have an issue with the clutch....

So just recently noticed a slight tear in the the rubber seal where the piston on the clutch lever connects to the master ccylinder..seems like hydraulic fluid might slowly be leaking out...could this possibly put air in clutch hose? The lever still has plenty of pressure when I squeeze...are there any other clues that could possibly lead to air in the line??

What! is wrong w my clutch I just wanna rip my f*cking bike already!!!

Edited by haole808

Air in the line would cause the opposite problem. If you had air in the line you would not be able to make enough pressure to push the slave cylinder. So the clutch would always be engaged. Your clutch is always disengaged. So something isn't returning to its normal position. Either the master cylinder is holding pressure in the circuit (not very likely). The slave cylinder is stuck (more likely). Or I assume there is a push rod because the slave cylinder is on the opposite side of the basket, So perhaps that's stuck. OOOOOOOORRRRRRR, the most simple and most common cause is that your springs are weak. That's just hard to believe because the bikes so new. 


I could be wrong about the air thing, but as a heavy equipment mechanic I deal with alot of hydraulics, and it doesn't make sense to me that air could cause the pressure plate to push against the springs. Air compresses a lot. Fluid compresses almost not at all. Thats why hydraulics work.

Have you had the clutch slave off to check it yet?

I think I would unbolt it from the engine, leaving the hydro line connected. Take the cover off the clutch reservoir. Try to push the slave cylinder piston all the way into the slave housing with your fingers. If you do get any movement further into the housing, It would displace fluid out of the res and I would take it to mean that either the slave cylinder piston was stuck or there was too much fluid in the system.

I've also experienced the throw out rod that runs thru the case between the slave cylinder piston and throw out bearing hanging up and not seating correctly in the throw out bearing. If that wasn't caught and was put together like that, it would lengthen the throw of the whole system. Seems to me that would cause the clutchpack to always be slightly disengaged and slipping.

Just a few thoughts for discussion.

I would just try getting new friction and steel plates.  If that doesn't fix it then you've eleminated that problem and have a new set for when they do go out.

buy a new engine. if that aint the problem then atleast you got a spare sitting around :lol:

Ha harryhand! Lemme just pull some loot off the moneytree in my backyard...jk..but still....

waiting for some time off work to mess around w the bike...appreciate the help everybody

Updates will be coming soon. Aloha

buy a new engine. if that aint the problem then atleast you got a spare sitting around :lol:

Haha, just sayin-process of elimination.  Last time my bike did exactly those symptoms it was just worn clutch plates.

So been trouble shooting the past few days and found a leak in my master cylinder where the plunger meets the rubber seal underneath the reservoir...since a new master cylinder is almost 300$ was gonna buy the rebuild kit.

On the bottom of my master is a 10...I've only seen kits for 9.5mm or 10.5mm.....has anyone bought one of these kits before??? What is the measurement for and do these kits help permanently fix the problem???

Could really use some feedback thanks everyone

Slapped a brand new master cylinder on that I scored off amazon back bled the line w a syringe and everything was back to normal!!!! Much thanks to everybody who helped out!!!! Sry it took so long to respond but w family work and other things it was just hard to find time. BRAAP

Did you ever fix the clutch problem? Just curious on to what it was .

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now