KX Riders
Maintenance & Technical => KX250 / KX125 => Topic started by: mustangfury on September 05, 2010, 09:30:02 AM
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:-( I have a '93 kx 125 and I believe the right Main bearing is worn because I took the cover off the motor and can feel a little play if I move the main drive gear up and down. I have also been getting a ton of oil out the silencer and I tried leaning the jetting and that stopped a lot of it and now more and more oil is starting to come out as time goes on. I believe the seal on that side is shot too and the oil from the crank is getting sucked into the cylinder.
The left side is fine. I just checked that about a month ago. The engine also makes a slight whiring noise when it runs that started a little while ago. I do not have a press or a shop oven to use for replacing bearings. I can probably find someone I know who has a press to do it though. How hard are the main bearings to get in and out? Do I need to remove the motor and split the case or can I service everything from under the right cover? Is there any other way besides heating things to the boiling point or using a press to replace these bearings?
Given I can find a press or way of replacing the bearings, my question is A.) Is there anything else that might be worn that I should look for in relation to the right side bearing. B.) Can I fix this myself as a doi it yourselfer and regular sockets hammers and basic mechanic stuff or do I need any special tools for splitting or reassembling the crank? C.) How much would be a reasonable price to pay for a shop to fix it?
Your thoughts are much appreciated,
Stang
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sound alot like you are on the right track, your mains and seals need to be replaced. you can do it your self with basic tools if you are carefull. it would be hard for me to explain how to do it with words alone on here. i am about to rebuild a kx 500 motor but it wont be for a month on so from now and could show photos on here of how its done. if that is to late for you i could probably do it using an old engine i have in my garage. how far can you get on your own i.e can you romove the head barrel clutch ignition ect
regards
john
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Winter is approaching and college just started so I have a lot of work getting ready to get dumped on me. I was hoping to get this knocked out asap so I am ready to go for spring next year. I don't have a garage either, so all my winter car/dirtbike/snowthrower repairs are done in the cold.
I have done top end rebuilds, had the clutch apart, and have had pretty much everything else apart on the bike except splitting the crank. I have a clymer manual and it talks about special splitter tools and according to the manual, a press seems to be a necessity. I have some steering wheel pullers and others that may do the trick of their little kawi splitter tool. The press I will have to look around for.
Should I pull the motor out of the frame after removing the stator, clutch, barrel, etc.?
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the best aproach is to remove as much as you can while the engine is in the frame as the frame dose a very good job of holding it still. you should be able to remove all most every thing bar actually spliting the cases. you can make a tool to split the case if you have access to drill and welder. old bearings can be knocked out carfully with a suitably size socket and hammer. new bearing in the freezer and cases in the oven and just drop them in. easy
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a pic of the spliter from the other side. this cost me about ?2/$4 to make and i have split at least 40 cases with it. you put the ignition cover bolts with some washers through the out holes and screw them in to the ingnition cover holes on the case then wind the center bolt on to the crank center and it will pull the cases apart. it will work on just about any bike, you just put more holes in it as you see i have
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Holy crap that is so simple! You just saved me a few $$. Thanks!
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When heating the cases in the oven use the spit method. as soon as they are hot enough to sizzle spit they are good to drop the bearings in. If the cases are not hot enough the bearing will get stuck and you have to press it out and start over. If the cases are to hot you run the risk of hurting the bearings temper with heat, not good. You can also heat the inner race of the main bearing and then drop the crank right in. You have to cool the crank in the freezer of cours. I have a speical aluminum plug that fits in the main bearing. you heat the plug and then set it in the bearing. when the inner race gets hot the bearing will stop spinning and then you know it's ready but don't get it to hot. Use a small screw driver to turn the bearing.When you feel drag pull the heated plug out of the bearing and drop the crank in. This is a very easy way to put the engine together but you can get it wrong very easy.
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BDI- i like the plug idea, i use an old impact socket.
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Thanks for the ideas guys. I will get as far as I can and will get back with questions. My trucks U Joints just started showing signs of binding in the 4x4 so that will have to be fixed first unfortunately :-(.
thanks again,
stang
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I have taken off the cylinder, carb, right cover, clutch, primary drive gear, left cover, and am working on the stator. Any suggestions on how to remove the flywheel?
I noticed there is a little play in the drive shaft bearing as well. Should there be play in that? It only moves a little. I just want to replace that while i'm at it if it needs it. It is the bearing on the shaft that the clutch bolts on.
I will probably have the engine pulled within the next hour or two. let me know what I should do next.
Thanks guys,
Stang
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you need the correct flywheel puller, they are on ebay. there is a pic below showing 2 pullers. the 1 on the left in the correct 1. i would not advise using the 1 on the right as that 1 can deform the flywheel. i would buy the correct tool for the job as anything else would damage the components, dont try and prise it off, again this will result in damage. to use the puller, wind out the center screw so that it will clear the end of the crank shaft then screw the boss (left hand thread) in to the center of the flywheel until it seats. wind the center screw in and put some pressure on. give the flywheel a light tap with a hammer, it may come off it may not, if not apply more pressure with the center screw, another light tap. continune until does come off. while you are spliting the cases i would do all that need doing
any probs post again
regards
john
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Ok, I got the puller yesterday and the motor is ready for splitting. Is there a gasket between the cases that will need replacing? Also, besides the loose bearings and the main shaft seals, is there anything else I should look to replace, specifically, while i have the case apart? Are there any common things that should be replaced any time you open the crank? Just want to do this right the first time.
I appreciate the help.
Stang
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When you pull the flywheel put a little grease on the end of the cranke so the puller does not guald up the end of the crank. Things I would recommend replacing are the output shaft bearing and the shift forks. there is no gasket between the cases just sealer.
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the most cost effective thing to do is get a complete set of seals and gaskets from ebay. as bdi said thare is no gasket in the center. the mains need doing, the crank seals are a must. i suppose anything else is upto you. depends on how long you plan on keeping the bike and how hard you ride and the budget you are on. perhaps split the cases and post some photos of the components and we can have a look.
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I greased the end of the puller and put a washer over the end of the crank to get the flywheel off. Came off real easy.
I will take pictures once i break down the motor and will post them.
Stang
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this is my high tech case splitting tools. steering wheel pullers work just fine but you need to source up the correct bolts. On the pullers I have the slots had to be lengthened by 1/8" with a round file but thats no big deal. I like useing two pullers when ever possible, on yamaha 450 engines if you let the cases get out of parallel to each other just a little bit it will crack the case where the shift fork slides in. On any engine if you let the cases get out of parallel you run a chance of screwing something up.
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nice when we going to split my cases?
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Cool, I have a steering wheel puller and i was wondering if it would work. The only problem i have is i dont have bolts long enough.
I was looking over my parts and the piston has some wear patterns on it. I was wondering what they could be signs of. This could be from the goofy mixture that was being run due to the leaking crank seal. I know the black crown is from all the crank oil getting in to the cylinder. I was just wondering about the marks on the skirt. Let me know what you guys think. My camera takes good pictures up close. If you need a zoomed in shot click on the image.
I will post pictures of the inside parts once i split it.
Thanks.
Stang.
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i would renew that piston. you need to have your bore measured too. i have not :| see marks like that on a piston before.
take the ring off the piston and put it in the bore as if it was on the piston about 1/4 inch down the bore and post a pic
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check your piston clearance
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The piston clearance was almost perfect when i rebuilt the top end. It only has about 5 hours on it.
I was running a really lean fuel mixture because I was getting a lot of oil out the silencer. That solved the problem for a short time, then it started spitting oil out the back again and that is when i decided to break down the bottom end. The excess oil was not from a rich mixture but rather from the crank case. I had the bike jetted pretty lean with a 150 main and a 50 pilot. The manual calls for a 168 main and 52 pilot. I kept seeing oil so I kept going leaner, one size at a time. I have never seen a piston like this either, that is why i am wondering if it is due to the lean mixture I was running.
The piston currently in it is a standard size. Fortunately if the walls are worn I will be able to get a B, C, or D size.
Stang.
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I would say it was trying to seize up.
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bdi, do you think the funny marks (the spirally curved marks) on the piston are due to vibration from the bottom end. the bore looks ok but should be measured i think
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oh sorry, I know what you are referring to now. The curling marks are an optical illusion from the way the camera picked up the lighting and the way the software compressed the full size picture. Click on the top picture of the three i posted earlier and zoom in to full resolution and you will see the ribs are running the way they should.
The marks i was wondering about were the two vertical lines on the intake side and the top wear on the exhaust side. the ribs are worn down a bit. BDI, do you think that the reason it was trying to sieze was from the lean(hot) mixture?
Here are two more pictures. They are a little darker but they don't show the ribs zoomed out.
sorry for the confusion. I guess you definitely haven't seen that before.
Stang
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oh sorry, I know what you are referring to now. The curling marks are an optical illusion from the way the camera picked up the lighting and the way the software compressed the full size picture. Click on the top picture of the three i posted earlier and zoom in to full resolution and you will see the ribs are running the way they should.
The marks i was wondering about were the two vertical lines on the intake side and the top wear on the exhaust side. the ribs are worn down a bit. BDI, do you think that the reason it was trying to sieze was from the lean(hot) mixture?
Here are two more pictures. They are a little darker but they don't show the ribs zoomed out.
sorry for the confusion. I guess you definitely haven't seen that before.
Stang
I would say yes.
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i though my eyes were playing tricks but its the camera, cool thats sorted.
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Drinking tranny fluid is exactly how my bike stuck 2 years ago... crank seal let go, without warning, in a sand wash, started going slurp, and stuck, boiled the radiator also....
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That's comforting to know that might be my only problem.
what were you using for trani fluid, ATF? Does it seize from simply too much oil?
The back of your piston looks like my last piston when i last did the top end. It had that little melted lip on the exhaust side. Mine was even more melted. It didn't seize or mess up the cylinder though. Those previous pics are of the same cylinder wall, no changes. I put in a plug one step hotter because I though that might help with the oil problem I was having. I went down the trail and it just quit. Being fairly new to dirt bikes, I thought it was from riding it hard and hotter. Once I rebuilt the top end, I realized that wasn't my problem, went to jetting, and now i am here. Learned a lot since then.
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I got the cases apart. The left main bearing did not come off the crank shaft. It came out of the case still on the crank.
How do you remove the shift drum?
Is there a way of removing the crank shaft from the right case half without the special tool?
Any suggestions are appreciated.
Stang.
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that sometimes happens. look at this vid http://www.youtube.com/watch?v=q38HUzr043c
those tool are expensive. but you can see what you need to do. if you made a case spliting tool like mine or bdi's steering wheel puller, you can use that. if you weld 2 or 3 bolts even in length to the outer bearing case and then use nuts on the end. if you do weld on the bearing be sure to sheld the crank from splatter. i have not done this before i have used the proper tool but see no reason why it wont work, its an idea anyway
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sorry stang, the shift drum, try and leave it in you should be able to work round it if you use blocks of wood. i use an electric of air powered impact wrench to remove the bolt, thay are normaly very tight with thread lock on
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Here are pics of the guts.
How about getting the crank out of the right case half?
Stang
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more pics
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if you put it on blocks of wood with the clutch side up. you should be able to tap it out, put a peice of wood over the crank shaft end so you dont bruse it and knock it with a hammer. if the wood splits get another piece. an extra pair of hands would be use full
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That's comforting to know that might be my only problem.
what were you using for trani fluid, ATF? Does it seize from simply too much oil?
The back of your piston looks like my last piston when i last did the top end. It had that little melted lip on the exhaust side. Mine was even more melted. It didn't seize or mess up the cylinder though. Those previous pics are of the same cylinder wall, no changes. I put in a plug one step hotter because I though that might help with the oil problem I was having. I went down the trail and it just quit. Being fairly new to dirt bikes, I thought it was from riding it hard and hotter. Once I rebuilt the top end, I realized that wasn't my problem, went to jetting, and now i am here. Learned a lot since then.
That is my 500 motor of course...
I was running Bel Ray Gearsaver....
The reason my main seal went...
was the Crank journal was actually sized small and no one caught it.. Odd as it looked perfect (no sign of wear or tampering...... (I bought it with a fresh motor).. so the main bearings actually were loose on the crank (didnt spin on the shaft) but could be installed and removed way too easy.... also guess what... the crank seal didnt seal properly because of thsi,,, bike got warm and started drinking oil...
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I tried running bel ray gear saver but the clutch was sticking really bad with it. When I would go to put the bike in first it would not go in easy. It would slam in and try to take off if I did not hold in the front brake. I don't know why. I was told you could use 10W-40 motor oil and that is what I have been running. When I put the motor oil in, I did not have the clutch problem anymore. It works fine? From experience, has anyone found motor oil to be a bad idea? If you have found it causes problems, what is the best to use to avoid wear?
Thanks.
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10w40 oil is fine as long as it meets the standard for motorcycles. Friction inhibitors are bad for clutches, it makes them slip. I ran ATF based on a after reading some chatter on this site. In 5th gear pinned I had the oil build up enough pressure it pushed out the countershaft sprocket seal. Going back to motor oil never had the problem. Stewart runs 30 weight non synthetic in his engines for what that is worth. Gear oil like a Bel-ray gear saver or Amsoil type stuff I would think would be good. I like most have run about every oil out there over the years and have my preferences like most people. Run what works for you. I run Amsoil 10w40 motorcycle in my K5.
Good luck!!!
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What designates oil meets the standard for motorcycle Transmissions? I am assuming it is one of the two letter codes/standards on the bottle? If so, which one(s) should I look for? Would synthetic be worse or better? I ran walmarts supertech non-synthetic.
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Usually API Service SG, SL/CF/CG-4, Jaso MA/MA2, ISO-L-EMA2 are all ratings that will work. Rotella 15w40 is a great all round oil. I have used it in 2 and 4 strokes and it is a great inexpensive oil that you can get at Wal-mart for less than $13 a gallon. It is made for diesel engines and holds up awesome.
What designates oil meets the standard for motorcycle Transmissions? I am assuming it is one of the two letter codes/standards on the bottle? If so, which one(s) should I look for? Would synthetic be worse or better? I ran walmarts supertech non-synthetic.
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(1) when you heat up the cases to put the bearing in, do you have to get all the bearings in with one heating or can you reheat it one bearing at a time?
(2) Will heating up the case with other bearings in it cause the case to crack because of different expansion rates of steel and aluminum?
(3)When you say the bearings will drop right in, do you literally mean you can just set them in or will you have to tap them in with a hammer and socket?
(4) how quick do you usually need to get them in before it cools too much: seconds, minutes, 10 minutes?
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I am looking to get the bearings in this weekend. Anyone have answers to any of my questions? any help is appreciated.
Thanks.
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They need to come strait from the freezer to the cases. I get my wife to get the bearings out while I get the cases out and then drop them in right on the range top. if the bearings are not cold enough the cases are not hot enough the bearings will only go in part way and stick. you also have to have the bearings real strait with the hole or they will not drop. I recomend 225 to 250 surface temp on the cases. any hotter you run the risk of ruining the bearings.I use the spit test, when it sizzles spit its' hot enough. put the bearings in the freezer atleast an hour in advance inside a zip lock back.
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Bearings are in! Piece of cake, thanks to all the help. Dropped right in. I am going to try and get the crank in and the motor back together tomorrow. I'll let you know how things go. If all goes well, I may be giving it a test run by the end of the weekend.
Thanks again for all the help everyone,
Stang
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Hmmmmmm, after that kind of confession I am not I want to come over for dinner on Sunday :-D
They need to come strait from the freezer to the cases. I get my wife to get the bearings out while I get the cases out and then drop them in right on the range top. if the bearings are not cold enough the cases are not hot enough the bearings will only go in part way and stick. you also have to have the bearings real strait with the hole or they will not drop. I recomend 225 to 250 surface temp on the cases. any hotter you run the risk of ruining the bearings.I use the spit test, when it sizzles spit its' hot enough. put the bearings in the freezer atleast an hour in advance inside a zip lock back.
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Stang, if you go to youtube and search "2 stroke bottom end rebuild " you will find a few good videos in 3 parts which help a lot when your doing it for the 1st time.hth, K.
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Put the motor back together, put it in the frame, and did the break in. Seems fine so far. I let it idle for 5 minutes and let it rest for 20. Then, I let it idle for 10 minutes and rested it for 20 minutes three times in a row. Finally, I road around my yard at quarter throttle for about 10 minutes.
Since my original jetting attempts were done with a bad seal, I put the rich main jets back in. It is definitely running rich, but it runs pretty smooth.
Thanks for the help everyone. Couldn't have done it without you.
Stang
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Stang,
If it helps at all I have my notes from back in the day & on my 93 KX125 J2 model with a 36mm Carb I used 52 Pilot, 170 Main, N1A1 Needle with the clip in the middle, # 6 Slide, 1 1/2 on the Air Screw.
38mm: The Same as above with the exception of a 180 Main, & 1 out on the Air Screw.
These settings @ 500' above sea level.
Hope some of this might help!
DoldGuy
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Took the bike out for a ride today. The throttle response is a lot better than before. all that crank oil leaking in must have been killing it. It used to be very choppy. The thing is crazy fast. First run from idle, effortlessly ran a power wheelie through second and into third gear, then ran out of field.
The rear fender still gets oily but not nearly as much as before. It mainly gets oily when I am running from 1/8 to 1/2 throttle. Otherwise there is little oil. I put in a lower pilot jet and that helped some, i think i might try one lower. Plug chop gave a perfect brown color. The mid range is very responsive. I'm not too worried about the oil if it has good response and runs well.
Thanks for all the help everyone. Everything seems to be successful.
Stang.
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Stang,
The # 6 Slide was the cure for the 93 KX125, if you are still oozing out of the silencer joint & exit the packing is probably saturated from before.
DoldGuy
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Do you know where I can get a #6 slide for a good price? All I found was $105.
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Do you know where I can get a #6 slide for a good price? All I found was $105.
Stang,
Check this link out:
http://www.rb-designs.com/
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Thanks for the tuning tips from your experience DoldGuy.
I found a decent deal on a #6 Slide. I put it in today and the low end power is sweet. The bike wasn't even warmed up and I was riding a nice power wheelie down my street off the get go. This is going to make sharp 180 turns a heck of a lot more fun!
Thanks again,
Stang
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Do you know where I can get a #6 slide for a good price? All I found was $105.
Stang,
Check this link out:
http://www.rb-designs.com/
Interesting stuff!