SuperMoto Junkie banner

KTM 250 SX-F overhaul

72K views 76 replies 32 participants last post by  Skully25 
#1 ·
I've been saying I want to start riding some MX for the past year or so and since I got a couple months off work because of my broken leg I figured it was as a good of a time as any to start looking around for a little project. might not be able to ride but wrenching keeps me from going completely crazy with boredom...

I started looking around at used bikes. the first plan was to get a 125 2-stroke because I figured if the engine went boom it wouldn't cost me a whole lot to repair. I started having doubts as I'm a pretty convinced 4 stroke guy, plus the fact my mates who had quite a bit of mx experience were telling me to ditch the 2 stroke idea wasn't helping either. some future supermoto plans for the bike made me go 4 stroke in the end. a 450 I knew was going to be too much for a guy with little MX experience, I already rode a friend's YZF450 around a pretty gnarly track and I was just about dangling on the end of the bars. so I was looking to go lite, ie 250.

I didn't want to spend a whole lot on the bike itself because I knew I was going to take it apart completely and overhaul it, so it didn't matter if there were some bits on pieces that needed work. I went with a 2010 250 SX-F. it doesn't have a link at the back like my 450 but I honoustly didn't want an EFI bike because KTM were having some issues with it the first year they made the switch, and since the 2011 250 was the first EFI 250 my only options were a 2010 or older model. carb'd and older style bodywork, had some 530 flashbacks already.

the bike itself was in a fair condition but you could see it had been taken apart once already and they basicly put it back together with just about any (rusty) bolt or nut they could get their hands on. nothing seemed to match and I'm that anal (yes I said anal) that it was bothering me a bit to see how the bike was reassembled. the bike had been run on sand tracks close to the sea, failure to hose the bike down ment a lot of stuff had started rusting and showed signs of salt eating it's way into metal parts. not stuff you want to see on a bike that's only 2 years old but again it wasn't a big deal since it was gonne be taken apart and cleaned up completely.

so enough with the boring text stuff, on to pictures. little sidenote, tips I highlighted in bold.

how it looked when I brought it in:




the easy part, removing plastics:



the suspension needed to be resprung, the guy I bought it from was about 220 pounds. I'm 140... little difference. luckily he kept the stock springs which work for my weight. out with the forks and shock. the front end also needed new head stem bearing. the triple clamps were tightened down so much I literaly had to knock the top nut loose, it simply wouldn't budge with just wrench. I was surprised I was still able to turn the bars considering how tightened down everything was.



biggest pain in the ass is I have no room for a work bench in the garage, I need to park my dad's car outside to actually have room to work in.



subframe off, again those bolts were tightened extremely tight. how I didn't find any stripped threads on this bike is beyond me... radiators off as well, flushed them out since they had some gunk in them.



engine out, bare frame left.
for those of you that want an easy way to remove the alu coolant tube from the frame, don't bother with the KTM tool most say you have to use. get a 12 mm hex socket for your wrench, insert that in the pipe and it will grip without doing damage. the top rubber piece will come out with a little wigling. when reinstalling the T-pipe you do need to use a sealant like loctite 577 to keep everything water tight



first cosmetic fix. the seat had a tear in it and the foam had some moisture damage. I sanded the foam down in certain area to clean it up and added an extra piece to make a step seat out of it. I also spray painted the foam to keep more moisture from seaping into it. the spray paint penetrates the outer layer of the foam making it more or less water repellent.



new blackbird cover for the seat. when you mount a new seat cover staple down the front and the back first to keep the cover in place. then start at the front and work your way back going from side to side keeping the cover tight every inch you move further back. once you get close to the back remove the staples you applied there in the beginning and reapply them so the that cover fits nice and snug. I found this to be the most effective way to keep the cover nice and tight around the seat. stapling it down in different areas then filling up the gaps will more likely leave you with a wrinkly cover.



started work on the motor but took it to a friend's shop to make life a little easier, now I actually had a bench to work on. the initial idea was to take it apart completely because I don't trust used bikes in general. by complete coincidence it turned out my suspension guy had gone through the motor at the beginning of the year since he knew the previous owner. he assured me the crank was good and a new piston plus camchain was installed. so I binned the teardown plans and just went over the obvious things. checked the valve clearances, all were within spec. checked the clutch, tiny amount of grooving on the clutch basket but nothing serious that would require work or a replacement part. springs and plates were all within spec. checked the stator and flywheel, found some dirt building up in there, mostly dust that found it's way inside through a stator cover weep hole at the bottom. drained all the oil I could, changed the oil filter and cleaned all the screens. ditched the stock hydraulic camchain tensioner and replaced it with a dirt tricks automatic one. the stock tensioners are known to fail and on a motor that spins around 12,000 rpm it's not something I want to risk. I've run dirt tricks tensioners in my last 3 bikes and they never miss a beat. they take 5 minutes to install and are fit and forget.




the stator cover showed some wear and tear. rather then buying a new one I choose to sand this one down and respray it. started with 80 grit waterproof to remove the old coating. then went to 200 grit to smooth the bare metal out.



primer, applied in several coats.



color, also applied in several coats



that's how far I am. got the frame and swingarm back from powdercoat today so reassembly will start saturday. I'm heading out to the UK on friday.
 
See less See more
14
#3 ·
well I was able to finish the ignition cover though it didn't go without a fuss. for some reason the orange paint reacted with the black eventhough they're the same kind of laquer. don't know maybe the black wasn't dried out completely yet though it had been drying for the last 10 hours or so... I had to carefully sand away the wrinkled orange paint until I hit the basecoat layer. pretty tedious work as I didn't want to sand away any other black paint on the cover, just the areas I painted orange. I then applied the orange paint again and it didn't react with the primer so glad that worked out, else I think I would have chucked it out the window :D

finished cover, it's not perfect but considering how the cover looked when it came off the bike it's a hell of a lot better. makes the 2 hours I spent sanding it worth it at least :lol:

 
#7 ·
one of my main issues... when I get bored I start spending money :anim_peep: good deal though, got a nice discount on the wheels, plus a brand new front and rear moto master rotor for free!

btw, this is just one of 2 sets... the other one will come in a couple weeks and will help the little 250 handle better on tarmac :D will also serve as a rain tyre set for the 450 should the need arise.

 
#8 ·
Nice looking bike nothing better than picking up a bike and tearing her down and putting in some wrench time. I too am finding myself in a similar boat as i just picked up a bike to get back into MX! However i wish i would have looked at a smaller bike like yours as i think i went alittle big for just starting again but o well. Any way good luck with MX riding its a blast and looking forward to seeing your progress with the bike!
 
#9 ·
Sweet, looks like fun! I need to post some pictures of mine soon, I should have the real deal Ohlins on it this week. :thumbup: I think you are really going to have fun on this 250. 450 it is not, but it is a lot of FUN to ride! Power isn't there, but that's not the point anyway. :D

Hey, those forks look old? <2007 possibly? :hmmm: Interesting...

Gerry
 
#10 ·
Hey, those forks look old? <2007 possibly? :hmmm: Interesting...

Gerry
yeah the forks and shock are from '07. noticed that when I went to look at the bike and it helped me knock the price down a bit :D

already had my suspension guy go over everything and all is still in decent shape, seals were only recently replaced as well as the oil. things are a little rough on the outside but nothing too bad.
 
#11 ·
so I started work on saturday, taking things easy and cleaning everything up along the way, most is more or less done. just need to get tyres mounted on the wheels, fit the rest of the plastics and get a hold of my graphics guy.

powdercoated frame, RAL2009 orange. installed new headstem bearings on the top and bottom. put the T coolant line back in the frame. used loctite 577 to make a proper seal between the 2 pieces.





motor in along with the swingarm. that one was powdercoated satin black and fitted with some new chainguides.



subframe prep. gave it a modest polish and installed some new plastics.



installed on the bike.



installed the headers. might run into a probleem with these. the bike was fitting with a full doma pipe that used a different header flange on the head. swapped out the flange and installed the stock headers but things feel a little loose. not sure of it's gonne seal properly or not... will know when I run it for the first time.



forks back on, easy.



front and rear brake needed some TLC. rear brake had quite a bit of dirt built up around the pads and inside of the caliper. took everything apart and gave it a good clean. little WD40 and copper grease works wonders. if you're doing maintenance on dirtbike brakes, always check the guide pins of the calipers. pry the rubbers loose and slide the caliper off, if the pins show signs of dirt or rust clean them up with some mild sandpaper or scotchbrite pad. regrease them and refit the caliper.



radiators back on the bike. bought a set of radiator guards as well but the radiators themselves were beat up just enough so that the new guards wouldn't fit properly... wasn't much I could do to change the guards to make them fit without putting stress on the radiators themselves so I binned the idea. money well spent... oh well.

also installed some samco hoses which to my surprise needed some trimming to make them work. the 2 hoses running to the bottom of the engine were slightly too long and got kinked when I installed them. had to cut them down about a half inch. should be plug and play normaly, the other samco sets I purchased never gave me any trouble fitment wise.

orange neken handlebars on there along with the powercoated barclamps. stock silencer back on that I got with the bike. still in new condition as it was taken off the bike right away. installed the ignition cover along with a case guard for the clutch slave. cleaned out the carb and fitted it with some orange breather hoses.



some more plastics that went on, we're closing on the finish.

 
#15 ·
it really is something I always wanted to do but since my previous bikes were all brand new ones I couldn't make those look any newer than they already were :lol:

this time I went the used route with the idea of making it look like new again.


250's seem to be the new thing :headscrat

that's a lot of orange. curious to see what your graphics come out looking like. your style isn't usually that...bright.
the graphics will even things out, and without the tank pretty much the whole frame is exposed as well so it all looks quite flashy right now.

first idea was to go with black and white again, this time more white than black. but I figured I already got a bike that's a bit more stealthy/less outspoken. so I flipped the book and said I'm gonne do the opposite now. not going to make everything super loud but I haven't had an orange KTM since 2006 so this time I'm sticking with orange :D

main idea is to use this bike for MX, hence I went with a 250. 450 is just holding on for dear life, hell I even doubt I'll be able to put the 250 to any decent use... maybe should have bought a crf150 :D
 
#16 ·
still no graphics but the rest is done.

fitted the wheels along with new sprockets and a blingy orange chain. chain made by esjot/HRT in germany, only half the price of a KTM orange chain and it actually looks like the orange will last, unlike the ktm ones where the orange paint just chips off. filled the engine with oil along with a new filter. did the same crankcase breather hose mod I did on my 450, route the line to the airbox and put a filter on the end.

the fun part came about when I tried to mount the tyres on the shiney new rims. I'm used to mounting my sm tires on my own and apart from dunlops slicks that have a pretty stiff carcass I can get most tyres on pretty easily. so I figured dirt tyres weren't gonne be that much different apart from the rim lock you need to put in there.

oh how wrong I was....

I went to tackle the rear first. getting the first bead on went fairly easy, put the tube in, still all is well... but then the job of actually getting the second bead over the rim, well that's where it went south... it's been pretty warm out the last couple days and after 10 minutes sweat was dripping from my nose. I wrestled that thing for over half an hour and could not get it on the rim. my left leg still not being healed up completely wasn't helping either. I watched dozens of different youtube vids of guys mounting dirt tyres looking for what the hell I was doing wrong... nothing really, I know I know what to mind when mounting them myself but I still could not get that sucker to budge. either the dunlops I wanted to put on were super stiff because there almost no give at all in that tyre. by this time the rim was already scratched in some places which evidently pissed me off even more to the point where I was about to dropkick everything across the garage :rant: I didn't even bother starting with the front...

into the trunk of the car everything went and off to a buddy who had a tyre mounting machine. even with that they were still giving me some grief before they finaly went on...:nutkick:

alright enough bla bla, pictures:




 
#19 ·
minor update but didn't take any pics yet because the weather has been complete crap the last couple days (summer... my a**)

made some frame decals out of skateboard griptape instead of fitting those large frameguards that woud cover up most of the coated frame. installed a acerbis plastic skid plate that I had to modify a bit to make it work with the KTM catch tank you can fit between the frame and swingarm.

finally made some progress in the graphics department. my regular guy was leaving me hanging so headster from gfx designs helped me out. design is done so I should have some decals on the bike very soon.

chances are the bike will see some supermoto use just for giggles on the smaller tracks I ride on. plan first was to just switch over the beringer set I have on my 450 since it will also fit on the 250. long story short as I was browsing some local used parts sites I stumbled across a used beringer kit (mc and caliper) for almost no money. little bit of cosmetic damage but for that price I couldn't leave it sitting. so off I went and I came home with an extra set of brakes. it's a gold kit so it'll kinda work with all the orange on the bike :D now I can supermoto both bikes at the same time without the hassle of having to swap over parts.
 
#20 ·
sooooooooooow... apart from a few minor glitches the bike is done. I did notice the left fork leg started to leak... changed the oil and springs when the bike was apart, seals were still good so maybe it's from sitting in the garage. cleaned it up, when through the seal with a feeler gauge to make sure there wasn't any dirt in there so let's hope it doesn't loose any more oil.

I also stripped a thread on the fork bottom to attach the guard :rant:... it was already damaged from the previous owner but I did too much and stripped it completely now. will need to look into how to get that fixed, drilling and tapping will be difficult because the hole isn't deep enough...

anywho, couple quick pics. still need to take some decent ones:

complete list what I did and parts added:
- powercoated frame and swingarm
- new headstem bearings and swingarm bearings
- went over the motor completely, new oil, filter, valve check, everything
- fitted a whole bunch of new bolts and nuts that were rusted or damaged.
- fitted the right springs in the forks and on the shock for my weight
- resprayed the ignition cover
- replaced all the fluids (brake fluid, clutch fluid, coolant, engine oil)
- fitted a new ignition coil, spark plug and spark plug cap
- changed most of the plastics and chainguides
- KTM slave cylinder protection
- Zap shift lever
- orange samco coolant hoses
- orange breather hoses for the carb
- orange neken handlebars
- KTM catch can
- K&N filter for engine breather line routed to airbox
- new renthal grips
- zeta bar ends
- zeta doughnuts on the grips
- renthal barpad
- excel A60/ talon wheel combo with dunlop geomax tyres
- new motormaster rotor front and rear
- custom graphics made by headster @ gfx designs
- blackbord seatcover along with step seat conversion
- acerbis MX style plastic skid plate
- homemade frameguard griptape
- AFAM sprockets
- Esjot/HRT orange chain






 
#22 ·
I pride myself on making my bikes look nice but they're no pit bitches :D

the 450 has over 30 hours on it, it's been covered in dust and mud from top to bottom, yet I still get comments it almost looks brand new when I arrive at another trackday....

obsessive cleaning? what's that :anim_peep: seriously though, once I start for me it does seem to have a therapeutic effect. same reason I spent almost 2 hours sanding and cleaning up that clutch cover... you can spend a stupid amount of time working on the smallest thing, if the endresult is there it can be quite satisfying.
 
#28 ·
Get it in SM trim and go have some fun eating the 450's round small tracks ;):bannana:

way ahead of ya :lol:

ran it up and down the street for the first time today, did take a fair couple of kicks to get it fired up but after that the engine ran nicely. had some decel popping but nothing too bad.

after I pulled back into the driveway I did notice one slight issue that does need a bit of work. the camchain tensioner cover was leaking quite badly eventhough I used a new washer when I installed the dirt tricks tensioner. the problem on the 250 is you got a coolant hose in the way and it's very difficult to get the tensioner out because there's a frame rail right in front of it, plus the motor needs to be at TDC if you're gonne take it out.

drained the coolant, undid the hose and tightened down the cover some more, hope that fixes it. if not, I'll have to pull some things apart again. these covers can be quite finicky, had some leaking issues with it on the 530 and 450 as well, but one those bikes you have easy access to it.

now available in supermoto, thing just revs to the moon...




 
#34 ·
nice!
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top