KX Riders
Maintenance & Technical => KX250 / KX125 => Topic started by: ihampson on December 23, 2007, 07:28:10 AM
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Hi, I am a bit confused about which parts are interchangeable.
I am trying to rebuild a 87 250 but am struggling to find good used spares. The r/h crankcase is cracked and the water chamber on the barrel is smashed. I have been told that the crankcases from newer engines (up to 92) will be ok with the 87 internals as there are only slight differences. but the dealers say that each year has a specific set, and the clymer manual has diagrams for 82-86, 87 and 88-91. In the manual some other internals stay the same (shift forks 83-91, shift mechanism 85-91 + kx125 85-91) exhaust advancer assy 87-91, clutch 87-91, primary drive gear 87-91, gear shift 84+) but there is two different gear assy (82-87 and 88-91) How accurate are these diagrams? Are they generic and only show the layout is the same but the parts may have different dimensions? Also the gear assy apears to be completely different. Is the way they fit into the case the same? maybe with different bearings?
I have found a mitaka conrod kit that claims to fit all years of kx, has anybody else used one? did you have to order a specific kit for your year bike? if one size fits all would it be a fair assumption to say the crank is the same?
Sorry for all the questions but i`m new to kx`s and this has got me beat. any advise or suggestions would be greatly appreciated.
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The Kawasaki web site has parts diagrams with numbers, unfortunatly its by model years, not by interchange. Look up the parts in question, if the part numbers are different, chances are they wont work. Kawasaki loves using the same parts as long as possible, sometimes for 30 years if they can.
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I dont know much about the transmissions.. But I do know that the cylinder and crank will definately work in the newer cases...
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Hi guys, thanks for the replies. cr480 i have been reading your other post about rebuilding you kdx engine and it was very interesting. I had previously been told that the kx and kdx shared the same bottom end but using a different top end, and a flywheel weight on the kdx to help bottom end power. I was a bit dubious, thought it might be another urban legend. From the sounds of it your rebuild is going well and would love to hear your progress, was everything straight forward or did it take a bit of modification other than the power valve rod?
Good to see there are some actual mechanics about rather than just fitters, which is the case at my local dealers.
Keep up the good work!
i have decided to buy the con rod kit after the holidays and hopefully it will fit. I also have a top end from a 89 bike which is NEARLY the same to mount as the `87. it fits the crank case, inlet, exhaust etc, exactly the same, the only thing difference is a idler gear for the powervalve, there is no recess on the case for the stub to fit into. Hopefully i can use a newer crank case so this wont be a problem, alternatively i will have to machine a small hole in the case so that it will bolt down all of the way. sounds extreme but looks quite straight forward. Time will tell i suppose. will keep you posted.
It would be good to create a list of interchangeable parts. maybe we should start a new post and we could update it as we go along? could save us all some money and hassle. And make it easier to find used spares from breakers, ebay etc. What do you think?
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My engine besides the powervalve lever and 2 cylinder studs(wrong length) was a direct bolt together deal... I had an '88 cylinder I was going to use before I bought the '98 and it fit the '91 cases just the same... I wouldnt be surprised if your internals will fit in the newer cases just fine, but I would buy a complete bottom end just to be sure... even if you have to swap in your good crank to make it a runner at least you'll know that the trans is right.
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Any advice regarding the stator and cdi? if the cranks are the same, are the flywheels and would i be able to mount the 87 ignition system? Clymer manual show different cdi`s for different years. they have various amounts and colours of wires so is each one specific to certain models and would it have to match the barrel and/or crank,flywheel .. or do i only have to match the stator and cdi?
the way i see it is if you can mount it and get a spark at the right timing it would be ok? or am i overlooking something that would stop it working? as i said i am new to kx`s and two stroke. all of my experience is with cars.
What are you using in your kdx cr480?
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I am using the Kdx ignition... I dont know if it will perform as well as the ignition that matches the KX cylinder but its what I have... I have used an '85 Kx ignition on my '84 tecate and also used it with a '84 kx cylinder with great results... I dont think the ignition changes between the years is enough to worry about.. As long as the stator bolts up to the case you should be fine
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Did everything bolt straight on to the crank ok and does the stator bolt on behind or in front of the rotor? i cant remember what mine is like as i haven`t really messed with it as i need a puller before i can get stuck into it. will go and check what mines like ...
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I have had a look at my stator and it is behind the rotor. I have also uncovered some new problems! it took me all of two minutes to take the rotor off with out a puller. the rotor came lose as soon as i undid the bolt and then i saw the woodruff key had sheared off. the pickups seem to be intact and ok but the seal behind the stator is leaking and has been patched with chemical metal (seems like a attempt to cure the leak rather than repair the case, hopefully!) do i have to split the case to remove that seal?
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yeah you have to spit the cases to change crank seals on kawasakis
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Well i suppose i have to split it sooner or later anyways. any luck it will come apart as quick as the rotor! Watch this space to see what other trouble i find!!!
How`s your kdx doing cr480?
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If the seal is bad theres a good chance the bearings need replaced too... As for my KDX I am having problems getting the crank true... I may just end up buying a new one... I still need to alter the powervalve lever, but I going to wait until the final assembly.. Other than that I have everything figured out... I really want to get it going so I can start a new project.
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I thought i would replace all of the bearings, seals and what ever else i found wrong anyway, just for piece of mind. its a long drive to the place my mates ride and the last thing i want is the engine to go bang and i have to sit and watch everyone else have all of the fun!
I have put some specs for your crank in your kdx post, they are from the 82 - 91 manual but could be usefull. is the crank bent or will it not press together true? Sounds like a nice project you got and has given me a bit more faith in getting my bike working sometime soon!
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Yeah pressing the crank myself with out a proper fixture has turned into a mess... its almost within specs, but I am having trouble getting the wheels to move with any sort of control.... If I dont get it dialed in soon I may end up just buying a new one
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Ive never pressed a crank before but a guy i know told me he uses v-blocks and some angle iron to make a jig for the bench press. Cant remember exactly how he explained it but next time i see him i will find out. What are you using to press it at the moment? What do you mean when you say "getting the wheels to turn"? Sorry, i`m new :?
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I mean that its already pressed together and the crank wheels are out of true in several directions... After messing with it for over an hour and it is still .006" out... Its hard to imagine, but the crank pin can press in crooked.. I used some v-blocks clamped to the crank while pressing, but its not even close to accurate enough for this kinda work... Its not even worth trying without the proper fixture...
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Can you buy fixtures or do you have to make one? i have never seen one before. Must be frustrating as you are only of by a fraction but that small amount can be significant at high revs.
precision engineering - easy with the right tools, a guessing game without!
what i`d give to have my own work shop!!!!!
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Actually I may just re-press it... Last night a guy I know here in town offered to let me borrow his pressing fixture, He used to race motocross and run a small engine repair business... I hope it works, he said it works good and they usually press very close to true.... I noticed that my new crank pin fits tighter into one crank wheel than the other. The press I was using had a pressure guage and one half took 12tons to press and the other less than 8tons... So if I get this thing trued I am definately having my buddy weld the pin..
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i would not weld the pin,, the pin is diffrent than the counter wieght matirel and its a single throw,,, crank springs the hollow rod pin smaller about .005 thousanths in diameter to hold it in place ... takes the right fixture to get perfect ,,,,,,,,,,,,,,,,,,,,,,,,,,,, check run out thread cr 480,,,
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Thanks for the input stewart :-) That is basically how I have been checking mine(I got the idea from your thread), my main problem is the pin wasnt pressed straight so I was of out of clock on the wheels and also crooked on the pin... Thanks for the heads up on the welded pin, it makes sense that a single throw crank wouldnt need it anyways... I am going to start over using a pressing fixture, hopefully It gets me close enough that I can get it true...
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Yeah pressing the crank myself with out a proper fixture has turned into a mess... its almost within specs, but I am having trouble getting the wheels to move with any sort of control.... If I dont get it dialed in soon I may end up just buying a new one
How are you trying to move the wheels? A nice heavy brass hammer works well, you have to get a bit viscious at times.
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When I true a crank I use a copper hammer because it is less likely to dent the crank weights then a brass hammer. I hold the crank in one hand and hit the weight that is out of clock with the hammer and then set it back in the V-blocks and check it. It is very hard for a pin to be pressed in crooked from my experience.
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When I true a crank I use a copper hammer because it is less likely to dent the crank weights then a brass hammer. I hold the crank in one hand and hit the weight that is out of clock with the hammer and then set it back in the V-blocks and check it. It is very hard for a pin to be pressed in crooked from my experience.
I would agree, if the pin were to be crooked you would notice damage either to the counter weight or the pin, and the pin is soooo hard don't think it would happen.
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How are you trying to move the wheels? A nice heavy brass hammer works well, you have to get a bit viscious at times.
my wheels were .030 out of clock initially and It doesnt seem to like to move that much...It was easy to get a couple thousandths out of it, but the more it moves the harder it gets to move... Maybe my hammer wasnt heavy enough? I was getting some pretty good whacks with it though... I was afraid I was gonna knock the crank out of the soft-jaws in my vice
I would agree, if the pin were to be crooked you would notice damage either to the counter weight or the pin, and the pin is soooo hard don't think it would happen.
I should probably get a new crank then. There may be somethin wrong with one of my crank wheels. I had .002 runout directly over the pin when I first checked the wheels after pressing.. and the pin pressed much easier into one side.. 8ton vs. 12ton..
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I should probably get a new crank then. There may be somethin wrong with one of my crank wheels. I had .003 runout directly over the pin when I first checked the wheels after pressing.. and the pin pressed much easier in one side 8ton vs. 12ton..
Not sure what your measuring over the pin, do you have a dial indicator on the crank wheel? It would not suprise me that they would be off .003. I think Stewart was chucking them up and truing them, but the measurements you need to be concerned with are on the bearing surfaces, I have a set of ways with precision bearings that I use, but them I've used V blocks and Lathe centers as well.
Thinking about it, the crank wheels do have a center on the inside, so they could be chucked up and trued to the rotating points, that would probably help make the motor run smoother than just truing the crank.
Stewart, are you truing the crank wheels in a lathe?
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Not sure what your measuring over the pin, do you have a dial indicator on the crank wheel? It would not suprise me that they would be off .003. I think Stewart was chucking them up and truing them, but the measurements you need to be concerned with are on the bearing surfaces, I have a set of ways with precision bearings that I use, but them I've used V blocks and Lathe centers as well.
Yeah i am using a dial indicator to measure.. With the dial indicator on the o.d. of the crank wheels one at a time there is very little runout.. maybe a .0005... so I know the pin is not in right... If it were simply out of clock 90degrees from the pin I would already have it trued... this crank is messed up.. I am gonna take it apart and try again...
Stewart, are you truing the crank wheels in a lathe?
I bet it takes some kind of grinder to remove the hard material that the cranks are made from
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If you don't mind hearing my two cents I would not take it back apart you can spread the crank by wedging something between the counter weights or you can go the other way by putting the counter weights in your vice with the soft jaws and giving it a squeeze.
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If you don't mind hearing my two cents I would not take it back apart you can spread the crank by wedging something between the counter weights or you can go the other way by putting the counter weights in your vice with the soft jaws and giving it a squeeze.
I dont mind at all... I will give that a try first... thanks for the suggestion
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Any luck with that crank cr480? I`m having some trouble splitting the crank cases on my kx. it seems to be stuck on the crank on the ignition side. I`m using a puller and have looked all around and cant find any bolts clips etc that would stop them coming apart.
Could the bearing be siezed on the crank and in the case? It doesnt apper to have been taken apart for a while.
Is there a hidden away clip somewhere or do i just keep tightening the puller?
dont wanna strip the threads or damage anything by going too tight. I have made another post "splitting cases?" that goes into more detail.
Any of you guys got any advise?
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Any luck with that crank cr480? I`m having some trouble splitting the crank cases on my kx. it seems to be stuck on the crank on the ignition side. I`m using a puller and have looked all around and cant find any bolts clips etc that would stop them coming apart.
I havent had a chance to work on the crank again... its at my buddies shop and he's been away... As for the splitting the case mine have always came right apart with gentle taps with a rubber mallet.. Are you sure you have all the bolts out?
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why not get your crank case welded?
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I should probably get a new crank then. There may be somethin wrong with one of my crank wheels. I had .003 runout directly over the pin when I first checked the wheels after pressing.. and the pin pressed much easier in one side 8ton vs. 12ton..
Not sure what your measuring over the pin, do you have a dial indicator on the crank wheel? It would not suprise me that they would be off .003. I think Stewart was chucking them up and truing them, but the measurements you need to be concerned with are on the bearing surfaces, I have a set of ways with precision bearings that I use, but them I've used V blocks and Lathe centers as well.
Thinking about it, the crank wheels do have a center on the inside, so they could be chucked up and trued to the rotating points, that would probably help make the motor run smoother than just truing the crank.
Stewart, are you truing the crank wheels in a lathe?
we are putting them in a od grinder between centers
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Hi mortisha, I know i coud get the case welded but it`s gonna look bad and there is damage to the other side casing aswell as the rear mounting has a big piece missing on the left side. it would also be easier to fit the new (`89) barrel to a newer crank case, rather than having to do more work to a case that is already a mess. And the bike is also a `89 bike with a `87 engine so would be making the bike something like original. That said, newer cases havent been that easy to find and definately not at a reasonable price so i could well end up rebuilding the old set and just keep my out for a cheap case and transmission. Am just looking to get it running again (cheaply) and then restore it to its former glory as i go along.
Managed to seperate the cases, had to get a better puller than the one i had and that still struggled. The bearing/crank/case were really tight together. maybe it had got too hot sometime or just hadnt been apart for AGES! My money is on both! No nasty suprises inside, the selctor drum and forks are worn but not too bad so i am gonna re-use them and see how they perform. Now that the engine has been apart once it shouldn`t be too hard change them afterwards. plus i will need different ones if i do change the casing so dont want to waste any money because i have got my eye on a kdx125 for the girlfriend.
Took her out on my dr650 on sunday and its too tall and heavy for her, (it weighs about 2 ton but goes up hills like nothing else!) and the 250 will (hopefully) be too fast to learn on. Does anybody know if a 94 kdx125 is suppose to have a rear drum brake? The one i`ve seen for sale has and i`m sure it shouldnt. am going to look at it in the next few days and want to be sure what year it is.
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Hi, if you want I can send you email of guy who did some case repairs for me, his work is 1st class, looks good and he is cheap.
where did you get the 89 topend from? ebay at a guess
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That would be good, thanks mortisha. Yeah the barrel came from ebay, small world eh? Where is this welder guy from?
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The guy is from monmouth. If you want I can pm you his email. If you send photo of what needs welding he will give you a price and you pay return P&P.