KLX250S Service

Discussion in 'Technical' started by johnnysneds, Apr 24, 2011.

  1. Hasn't had much attention lately so thought I would service the old KLX.

    Before: not too much different looking until you start stripping her down.









    Swing arm was removed and all joints removed, cleaned and lubed.


    Corrosion at lower roller bearings from sitting water that breached the seals




    Thoroughly cleaned from old grease and re-lubed.




    Re-assembled and ready to be installed.






    I use a bucket of warm soapy (washing up liquid) water and a sponge to clean my chain. Leave it in the sun until dry and lube with Motul Offroad Chain Lube. Good stuff you can see it penetrating the o-rings as you spray it on.



    A happy, clean and lubed rear end. Onto the front....



    Still plenty of grease apparent from the last time I lubed the steering stem up 3,000 Km ago.


    Remove all the old grease and put plenty of new stuff on.


    Bearing installed with dust cover.

    Lower bearing also still plenty grease apparent from last service, nice.

    Cleaned and re-greased

    Forks re-assembled and all electrics cleaned with WD40.



    Front wheel bearing maintenance. Required plenty of cleaning and re-greasing.





    Rear rack has been modified to mount a Kolpin 1.5 gal fuel tank, really handy and easy to get on and off. I have two of these and one is used for water. More info can be found here: http://www.kolpinpowersports.com/products/water-and-fuel-packs/fuel-pack-jr-with-pack-mount.html





    Also the engine oil was replaced with Motul, oil filter replaced, new spark plug (correct gap set) and the No-Toil two stage filter was thoroughly cleaned and re-sprayed with Motul Air filter oil.

    Nice and easy to work on the KLX
    And here she is all ready to go for some more adventure....







  2. Enjoyed that pictorial walk thro of your very comprehensive service. How long did that take you to do?
  3. Oh I started Thursday and finnished yesterday afternoon. Not rushing though taking my time and doing it properly.
  4. Awesome Johnny! You are an inspiration!!! Now that you've got the WR will you keep the KLX? Happy Trails! Tony
  5. I actually love my KLX, I've pulled it out of ditches, rivers you name it, lift it upright and the thing just fires straight up. It has been my first off-road experience and every minute has been a pleasure on it. Some might say it's a little underpowered, well I suppose that depends on your experience. For me it had bags of power off-road. I've been on rides with guys who have all the Carlos Fandango bikes and she's managed just fine, nothing to be embarrassed about. It also has a good top end which would put some 400+ bikes to shame.
    Bang for bucks I don't think anything comes close to it in Thailand, legally.
    It's a good back up for the WR. Depending on how the green book goes I may or may not sell.
  6. Great post and really clear photos. Funny enough, after following all your work on the WR450, I was thinking how good it would be if you did the same with a KLX250, saying as how a lot more people have them.. and you did! Thanks, and I am hoping there might be a few more installments and tips of how to keep them running sweetly and maybe even how to tune them up slightly.
  7. The mods I've done to my KLX go something like this:

    First thing I did was de-restrict. Re-routed the wire to the ECU which allows the engine to rev to it's limiter in all gears. Most people this is the first thing they do.
    I also bought an aftermarket Thai exhaust slip-on but this fell apart several times. On it's final farewell it completely departed the motorcycle and narrowly missed a friends head in Cambodia, oops sorry F. Now there is exhausts kicking about the Kawasaki shops etc but what a price there asking form them. All I did was get a hold of a second hand FMF slip-on took it along with the bike to one of these exhaust places and got them to make a pipe up for it that will mate with the stock header. I was chatting with Ian Bungy about a power bomb header pipe that can be manufactured locally. What these do is exhaust gases passing through the power bomb expand, cool and accelerate increasing flow. He swears it makes a big difference so I will give it a go soon. Moreover this power bomb will act like a pre muffler and hopefully quieten my booming exhaust down a bit.
    Now I also have a contraption fitted to my bike called a Memjet Module. It's fitted inline with the air intake signal. It has a manually operated dial of infinite settings which will intercept the signal from the ECU to the butterfly, amplify it to increase the amount it opens. The ECU should sense the increased intake of air and alter the ignition/fueling to suite. This also will give you a wee bit extra power. Too much though and it starts coughing and farting as the mixture becomes too lean. It will drop your mpg quite significantly also.
    You can remove your snorkel on the top of your air box to increase flow, however I put mines back on as any dirt/water gets in easily. Not worth the insignificant increase in performance in my opinion.
    Now depending on what you use your KLX for this next mod will produce the biggest single noticeable change out of all of them, without going for a big bore kit that is. If you mostly ride on the road I would just leave the gearing as is, however if you spend most of your time off-road and not worried about top speed, change your sprockets. I need to check but I think I went one down on the front and a 48T on the rear. Now you'll probably think the mods previous to this made a difference, combine them with the sprocket change and you won't believe the difference. I run my rear tyre pressure around 18psi and have ripped off two stems. Yes I need to fit a tyre lock, the point is it didn't do it before the gearing change. I want to try a 50 or 52 tooth rear sprocket to see if the front end can come up any easier when riding holes/bumps on tricky trails. This is an area which let's the KLX down for me, but it's not a biggy. I thought it might just be my limited ability but no, I rode some trails on my WR last week and this does it no problem, fantastic, but that's another thread.
    I believe you can now buy Power Commanders for them and I'm sure it will smooth out the fuelling, however I think the fuelling is pretty good from the injection system as it is.
    Not long ago I was looking into a 350cc big bore kit. It would be a very interesting project and one I still want to have a go at, however my priorities have change for the time being but I'm sure I'll get around to it again at some point. I think there's a thread on here somewhere and a chap from Indonesia has successfully done it with great results, it did however cost him over $3000. Cheaper options will become available as the more people figure it out.
    I've personally been very happy with the mods ive done to my KLX. It's kept a smile on my face over the years and still does.
  8. Very interesting Johnny!
    I have just bought a KLX and now contemplating various upgrades, I took off the snorkel and can at least hear the difference ;-) the air intake opening is now twice as big as with snorkel so I hope it makes a difference and also hope the filter does it's job with keeping the dirt out, note you use a No-Toil filter, where can I get that in Thailand?
    I did already order an exhaust with power bomb header from Ian's contact in Chiang Mai, Bht 5500.- and arrived last saturday by EMS at my place in Bkk, have not installed it yet.
    At the recent motorshow the Kawa Rama 9 staff told us that some people are working on an better ECU for this engine, in tests people have done 160 km/h they say...supposedly ready for sale in a few months, not surprised as think especially all the D-Tracker kids cant wait to get more power out of this engine so a proper ECU would sell as hot cakes.
    The sprocket upgrade is interesting, where did you buy those?
  9. Hey FrankT,

    Congratulations with your new bike, im pretty sure your going to love it.

    Actually the air filter that comes standard with your KLX is pretty good, not sure but i think its a two stage one, will need to double check. Its just I ordered a No-Toil without knowing this. So I just fitted it since I bought it :think:

    You can pick-up Renthal sprockets at Dirt Shop, Bangkok, you should also be able to get a two stage filter there also if required. Not sure where you are located, if Pattaya theres a handy dirt bike shop in the East Side of Pattaya I previously used. Its a pain to find. If this is of any interest to you let me know and ill see if I can track it down in google maps and send you the co-ordinates. It has all the good stuff or the really helpful guy who runs it will be able to get you what you want in no time.

    My KLX has done a GPS indicated speed of 148km/h (before changing sprockets). Now do you really want to go this fast on one of these, its not comfortable at these speeds. Anything over 130 and it becomes unstable. I would suggest forgetting about top speed (thats for Hayabusas) and gear it down so it max's out at 120, you'll have a wonderful time off-road with it.

    Save your money on the magical ECU and put it towards a Scott Radial Damper.

    Cant wait to hear how you get on with it, please let us all know.
  10. Buy the Air Box Snorkel from a Kawasaki Boss 175, You need to file a little on each side of Your Air Box Lid but it is very easy to do and once Fitted it increases Airflow considerably without Risking Water entry which is Possible if you just remove the Stock Snorkel or Lid? All the Mods make a Marked Difference when combined as Johnny says they are a Great little Bike once You get them going well and amazing Value for Money!
  11. Thanks for the motivation Johnny, got off my duff yesterday and went down to Nana Screws and purchased a large quality socket set to fill out the few tools I have.

    Asked the Kawasaki Dealer to do the same work at 29,000 km, which they said was unnecessary at that mileage but they did, where we found that dry swing arm bolt and a head bearing in need of replacement (both of course were replaced). :roll::cool:

    Now at 50,000 I feel the need to have a good inspection of all the moving bits; always stripped down my own MX bikes every winter and your pictures showing that you enjoy this work remind me to get at it.

    The Kaw Boss snorkel is another of those phenomenally cheap mods for the KLX's.

  12. Hi Johhny,

    I live in Bkk and already bought some parts at Dirt Shop, will have a look again for the sprockets.
    Agree this bike is not for speed but a bit moreg runt would be nice, steep up-hills can be a bit of a struggle I noticed altough, again, the sprockets could make a big difference.
    If I go for new sprockets can I still use the old chain?
    What's the Scot Radial Damper?
    Hope to get my license plate today and then we are off to Pakse Friday for a 5 day ride around the Bolaven plateau ;-)
  13. and oh, the big bore kit they use in Australia and USA only works for the carburretor engines, not for the fuel injected ones we have here...such a shame...
  14. You might be able to use your existing chain, depending on what size rear sprocket you go for and how much adjustment is left at your rear axle nut. I put a Renthal o-ring chain on anyways and kept the stocker as a spare if I ever go back to stock sprockets.

    Read about Scott steering dampers here: http://www.scottsperformance.com/Stabilizer_Purchase2.php?Make=Kawasaki&Model=KLX&Bike_ID=5432&Year=2011&Size=250&Fred=S&BI_ID=144233 This is the one for your bike. It provides high and low speed damping to your steering. High speed damping is the important one, if you hit something off-road ie a large rock the damper will control the deflection and hopefully the bike wont go off in an unwanted direction. Ive tried it and it works.
  15. Yes they do work on the EFi models, its just there hasnt been a lot of success stories so far. Its ever so close to being perfected so watch this space......

    Read the last few posts in this link from KLX331CRAZY: https://www.gt-rider.com/thailand-motorcycle-forum/threads/34052-KLX250S-(EFI)-Big-Bore-Kit
  16. Well let us know how you get on.
    And thanks for the info on the Boss snorkel Ian, wasn't aware of this. Another chance to get the Dremmel out, awesome.
  17. All clear Johhny, talking about Scott, is that the same people who make those chain oilers? Woudl you recommend that too?
  18. Hi Guys,

    I'd been following the threads on KLX250 and keen on buying one for off road riding. I'm still searching for KLX 250 with carb which is 2010 model overhere in Malaysia with future big bore upgrade.
    Otherwise I had to buy DFI KLX250, I am interested in the modification of rerouting the limiter as Johnnysneds had done on his bike. Would anyone show me how is it done in detail, please?
    Please be warned that I am not mechanical/technical inclined.
  19. Click on this link and it will download a a pictorial procedure for derestricting the KLX


    Ignore the Russian writing just follow the numbered steps. If you any difficulty with the pictures send a PM and ill take some clearer photos from my own bike.
  20. Hi Johnny, a few clearer pictures would be much appreciated as I am still a bit puzzled..., tnks, Frank
  21. OK you'll have to give me a day or two and ill post up a nice pictorial walk through of how to do it.
  22. :smile1:Thanks:smile1:

    Please take clearer photos, maybe you can post it here as reference for others.
  23. Firstly remove your rear rack if you have one. Then your seat and the left hand side panel.

    It should then look like this.

    Disconnect the negative terminal of your battery and then the positive and ensure the cables are clear from the posts.

    This is your ECU

    Gently pull it off the upper and lower securing brackets.

    Depress the connector with your thumb as shown, you'll hear a click. With your other hand disconnect the loom/connector from the ECU and store the ECU somewhere safe.


    At the lower part of the connector at the rear you will see a light green wire. Snip this wire approx. the same length as in the photo.

    The yellow wire you see is additional. Get a piece of say 24" long, this is more than enough and the excess can be snipped of later. I put some plastic sheathing over it to give some extra protection. Prepare both ends and tin them ready for soldering as shown.

    Put a piece of heat-shrink over the longest end before you solder both ends together. Solder the ends and slip the heat shrink over the joint as shown.

    After finishing off the heat-shrink/joint with a heat gun it should look like this.

    The other snipped end of the light green wire ensure you put a piece of heat-shrink over the end and isolate it with a heat-gun as shown.

    Your now finished with all the fiddly stuff here and hopefully it should look something like this, or better.

    Leave the ECU out of harms way until the other end is complete.

    Where your bum is roughly parked when riding you will see three connectors, the one of interest to us is the one in the middle.

    To make life slightly easier remove the two rubber connectors just forward of these three connectors. You'll have more access.

    Ok back to the connector. First you remove the connector by using a small screwdriver, press gently down on the clip as shown.

    Pull the connector free with your other hand. Note: the black and clear sections of the connector remain connected.

    Pull the female end of the connector free from the bracket as shown. This is the end we will be working on.

    At the rear of this connector locate the black wire with a red stripe. Be careful there are two black wires, one has a brown stripe. The one you want is at the corner of the connector as shown. Snip this wire as shown in the photo.


    Remove the black/red wire with crimp from the connector. Use a small watch makers driver from the front to release the crimp. (ignore the terminal block connected to the wire)

    Now it makes things a little easier if you solder a short piece of wire onto the piece you just removed to give you a little bit more free play to work with.

    Put a piece of heat-shrink over the joint and heat gun it into place. Tin the free end ready for soldering.

    The yellow wire from the ECU you have to route this up to the connector you just removed, you should have plenty extra. Snip the yellow wire (or whatever colour of wire you are using) so that it matches with the other end of the black/red wire you snipped earlier. Twist these two together and tin them ready for soldering.

    The crimp connector that you added the small extension too, solder this to the black/red and yellow wires that you just soldered together. You will now have a "Y" connector like shown in the photo.

    Slip a piece of heat-shrink over the "Y" splice and use a heat gun.

    You should end up with something like this.

    Insert the crimp back into the connector until you hear it clicking into place.

    Slide the connector back into its bracket.

    Connect the other end until you here it clicking into place.


    Put the lower two rubber connectors back onto their posts and your finished up here and it should look like this.

    Get your ECU. While its off give the connector a good check for dirt and corrosion and clean as necessary.

    Mate the ECU and connector fully back together carefully. And slip the ECU back onto its upper and lower brackets. If you've any excess wiring tidy it up by using a cable tie around the sub-frame as shown.


    Connect the your battery. Fit your L/H panel and seat.

    Your bike is now de-restricted.
  24. Wow, that's one of the best DIY technical explanation so far!
    Thanks Johhny!
  25. Thanks for that. I appreciate what you have shown other people to do and I don't even have a KLX . Very decent of you and it saves people having to spend money to derestrict their bikes. Good man yourself.

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