Main Bearing Repacement

[mustangfury]

  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

[jonny500]

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

[mustangfury]

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.?

[jonny500]

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

[jonny500]

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

[traileater]

Holy crap that is so simple! You just saved me a few $$. Thanks!

[BDI]

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.

[ShadeTreeFab]

BDI- i like the plug idea, i use an old impact socket.

[mustangfury]

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

[mustangfury]

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

[jonny500]

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

[mustangfury]

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

[BDI]

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.

[jonny500]

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.

[mustangfury]

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