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2003 Ktm sx125 not running right

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Hi all, I have a 2003 Ktm sx 125 new to me so I'm trying to get through all the kinks. I'm quite familiar with 2 strokes from rebuilding hand fulls of Blasters but I'm unfamiliar with powervalves. So here's the issues I got the bike to start first kick during the colder months about 30 degrees. It would start first kick every time. Then once it started warming up I cleaned out the carb and set float height. It's got a 190 main jet and 48 pilot w/ full Pro Circuit exhaust. I replaced the rubber head o rings and put a new spark plug in too. Along with 93 octane mixed 32:1 with ams oil interceptor. Once the weather warmed up to 70-80 i tried starting it and it would barely start with choke. Would just bog out. I messed around with the 2 screws on the carb, the plastic one with a spring and a small brass on the bottom. Got the bike to start but doesn't first kick anymore. Also after riding it I noticed a bunch of spooge coming from header meets silencer, there's no flange there. Radiator hose wouldn't fit would rub a lot on rear shock. Sorry for such a long post just trying to get all the details there. Would like your guys opinions on how I can make it run better. Thanks :ride:

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Hi, KTM recommend 40:1 mix for your bike ie 125ml of oil per 5 litres of petrol. There should be a rubber sleeve fitted to the joint between the pipe and silencer. The screw with the spring lifts the slide when screwed in. The other screw is your airscrew which should be 1.5 turns out if your idle jet is fine. It should tick over smoothly. When warmed up if you  have less than 1 turn out go richer on the idle. If more than 2.5 turns out go leaner. You have to change your jetting from richer to leaner as the weather warms up and it may mean you could go to a 45 idle. Try and get the a/s set correctly first to see what effect it has. Also, you could check your reeds to ensure they are not chipped and closing fine, as this can also make a bike difficult (but not impossible) to start. Also bear in mind you jet for temperature, altitude, track/ground conditions and how you ride it. These motors like to be worked hard. Presume AMS is fully synthetic oil - not familiar with it. Hope this helps. Bob.

Edited by 7Tktm

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3 hours ago, 7Tktm said:

Hi, KTM recommend 40:1 mix for your bike ie 125ml of oil per 5 litres of petrol. There should be a rubber sleeve fitted to the joint between the pipe and silencer. The screw with the spring lifts the slide when screwed in. The other screw is your airscrew which should be 1.5 turns out if your idle jet is fine. It should tick over smoothly. When warmed up if you  have less than 1 turn out go richer on the idle. If more than 2.5 turns out go leaner. You have to change your jetting from richer to leaner as the weather warms up and it may mean you could go to a 45 idle. Try and get the a/s set correctly first to see what effect it has. Also, you could check your reeds to ensure they are not chipped and closing fine, as this can also make a bike difficult (but not impossible) to start. Also bear in mind you jet for temperature, altitude, track/ground conditions and how you ride it. These motors like to be worked hard. Presume AMS is fully synthetic oil - not familiar with it. Hope this helps. Bob.

Right on

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Alright update on the Ktm, I drained the gas and mixed up some 40:1, and yes ams oil is full synthetic. I then removed the full exhaust to clean up the mess. I was able to get a good view at piston which didn't appear to have any gouges on it. I took a video and I'll upload the link later. But I thought since I was already here it would be a good idea to leak test it. It ended up not holding any air. I used soapy water and sprayed everything even tester but no air bubbles appeared. So this tells me it's either a bad clutch seal of middle case gasket. Hoping it's the clutch seal. Earlier I had to replace water pump seal because coolant was getting into oil. This may have something to do with that? I'm looking at getting the all balls crank seals. But I also saw the tusk complete seal kit, is that any good? 

 

Edited by Blaster528

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Buy OEM everything for bearings and seals unless you enjoy doing it twice.

Replacing you main seals is a major pain. You might as well get new main bearings if your going in that deep.

 

But it sounds like its just you jetting being way to rich. The manual should have a breakdown of what jets to use at certain temperature and elevation... The Aftermarket pipe will little effect on these specs.

 

If you main seal was bad the bike would be burning oil. So I would verify that is the case before you waste your time...

Unless it failed on the magneto side in which case it would run lean like it had a vacuum leak.

 

 

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25 minutes ago, 2strokezuke said:

Buy OEM everything for bearings and seals unless you enjoy doing it twice.

Replacing you main seals is a major pain. You might as well get new main bearings if your going in that deep.

 

But it sounds like its just you jetting being way to rich. The manual should have a breakdown of what jets to use at certain temperature and elevation... The Aftermarket pipe will little effect on these specs.

 

If you main seal was bad the bike would be burning oil. So I would verify that is the case before you waste your time...

Unless it failed on the magneto side in which case it would run lean like it had a vacuum leak.

 

 

How is replacing the clutch seal a major pain? All that has to be done is remove clutch basket and primary drive gear.. no?? The bike does smoke a bit and Im going to check oil level tomorrow. Im quite certain its the clutch seal and or stater seal since the bike has been sitting for over 5 YEARS. When I leak tested it I sprayed the crap out of stater seal and saw no bubbles. I agree oem is best but there are no other good brands out there? I know alot of companies just put there name on certain seals.

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There is no such thing as a clutch seal.

You are referring to the crank seals, 70 & 71 on the link. 

http://www.cheapcycleparts.com/oemparts/a/ktm/524b74c0f8700231ac495885/crankshaft-piston-125-200

You probably don't have to split the case, in which case it wont be that bad. Also remember the primary gear bolt is reversed threaded when your taking that off.

 

I have been scrw**d over so many times with bearings and seals from PivotWorks AllBalls Moose ... all of them. 

If you want to save money try to find someone selling OEM ones on EBAY. I find genuine KTM stuff on there around 50% of the time.

Anything aftermarket will be made in china.

 

 

Edited by 2strokezuke

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4 minutes ago, 2strokezuke said:

There is no such thing as a clutch seal.

You are referring to the crank seals, 70 & 71 on the link. 

http://www.cheapcycleparts.com/oemparts/a/ktm/524b74c0f8700231ac495885/crankshaft-piston-125-200

You probably don't have to split the case, in which case it wont be that bad. Also remember the primary gear bolt is reversed threaded when your taking that off.

 

I have been scrw**d over so many times with bearings and seals from PivotWorks AllBalls Moose ... all of them. 

If you want to save money try to find someone selling OEM ones on EBAY. I find genuine KTM stuff on there around 50% of the time.

 

 

Alright good to know ill check out ebay. I figured it was called the clutch seal since it was on the clutch side and it keeps the gear oil from entering the cylinder? Thats what all the blaster people call it:blink:  But before I do anything ill look at the amount of gear oil that comes out. Also when leak testing is there any vent lines you need to block off, I couldnt find any. 

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Alright drained the oil and about 650ml came out and I put in a littlest less than 700ml 2 months ago. The oil was greyish so maybe that's because it was the first change since I replaced the pump seal for the coolant? Or the seal went bad again since the bikes been sitting. 

IMG_3647.JPG

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Alright so then it would appear my right side crank seal is fine? I tried leak testing but i think all the air was coming out the power valve

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46 minutes ago, Blaster528 said:

Also is .77mm too much for big end bearing play

side to side or up and down ?

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11 minutes ago, kxrob said:

side to side or up and down ?

Side to side. I snuck a feeler gauge in through the intake. No up and down play

Edited by Blaster528

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 Fix your jetting rather than chasing bigger issues.  

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5 hours ago, seer said:

 Fix your jetting rather than chasing bigger issues.  

I thought it was wise to get the big issues out of the way then tweak out the little issues. Also back to 7Tktm I did find that my reeds were chipped and a little bent up. I ordered some boyesen pro reeds carbon fiber 

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