Rebuild help

[Rockytop20]

I am new to all of this and I recently bought a 1997 kx250 from a guy. The top end is off ready to be send of to be re-plated. I have looked down into the crankshaft and can see some kind of metal shavings. I really though I would try to avoid splitting the case by trying to flush out the shavings (probably not the best idea, I know). I noticed that the lower rod bearing looks to be messed up on one side, which I think could be some of the metal that ruined the cylinder in the first place.? So it looks like I will be splitting the case. My question is would it be cheaper to buy the tools to remove the flywheel,split the case and remove the crankshaft or take the motor and have the dealer use the tools for me? Thanks for any advice you can give.

 

[fatboyslim]

Way cheaper if you buy the tool but if you can't get a hold of the fly wheel puller then get you and 2 other friends with long screw drivers wrapped in soft material as to not damage the flywheel and brace them behind the fly wheel and at the same time pry it off keeping the pressure even and careful not to damage your stator.

 

[whenfoxforks-ruled]

Way cheaper if you buy the tool but if you can't get a hold of the fly wheel puller then get you and 2 other friends with long screw drivers wrapped in soft material as to not damage the flywheel and brace them behind the fly wheel and at the same time pry it off keeping the pressure even and careful not to damage your stator.

Here I was under the idea that using a 3 jaw puller to attempt rotor removal was a really bad move! The rotor removal tool is cheap, under 20 dollars and most shops carry them. Splitting the cases ideally, needs a case splitter, 3 digit expensive, but you can modify a car harmonic balancer puller, cheap.

 

[Rockytop20]

Thanks for the help. I have a 3 jaw puller but im guessing by your post it will mess things up? What would I have to change on the balancer to make it work? Is it just changing the bolts to 8mm or 6mm?

 

[whenfoxforks-ruled]

The 3 jaw draws from the rear, if it does not fly off, break, or make the rotor fly about 20 feet very quickly, it just is not the correct tool. 8 to 14 dollars lands you the correct tool that draws it from the front threads, and does not damage the crank end. Right about the puller, you use the large screw to draw the case off using the crank end again, put something soft to squish against the crank, brass is nice, if the end has a pivoting end, leave the nut on full thread flush. The case screws go into the threads for the magneto cover, sprocket cover if it reaches, make sure they are all the way in and the puller is parallel to the case. A lot of times the center case screws are long enough with some washers, and use washers to shim the puller if crooked. You may have to tap the countershaft to keep drawing it apart parallel, brass, lead, or a dead blow hammer. The first time is the worst time, and the better tools make it a lot easier to perform, and are pretty universal to all dirt bikes. Motion pro makes some nice stuff. A plate of aluminum, the size of your cases, and that draw screw from a c clamp and make a custom splitter, heck, put two of the draw screws in it, put one by the counter shaft. Drill a hole where ever you can get into a threaded hole in the left case. Bolts all the way into the right case could be a problem, caution. You can turn it around if need be and push the crank out of the other case with the same set up.

 

[Rockytop20]

Can anybody with a splitter tell me what size bolts they should be and how long? I think they are either 8mm or 6mm?

 

[whenfoxforks-ruled]

The bolts that hold your ignition cover on, are the same size as the center case bolts, just longer. If they are too long, shim it up with washers. The diameter is important, and the thread pitch. The hardware and even menards has handy go- nogo gauges to determine what you have. The parts micro fiche will tell you the proper size also. Figure how much goes in for full thread, add the distance to the pulling face of the puller, get the next size longer. And a bunch of washers.

 

[Rockytop20]

Do I really need a flywheel holder and is there any trick to get around using or making one?

 

[whenfoxforks-ruled]

You can jamb something softer than the gear in between the teeth, IMO that is nuts, too much stress. An impact wrench/tool will eliminate the need for any holder.

 

[jsantapau]

oil filter or strap wrench that will wrap around the flywheel snug and tightens as you apply force is the basic idea. just make sure you take the primary drive gear(clutch side) first before you take off the flywheel. works well on bikes that have the trigger coil on the inside of the flywheel,might not work on the kawasaki

If you have an old tie down strap you can try wrapping it snugly around the flywheel (the opposite direction you want to turn the nut) a few times and then tying the loose end to the frame or something that is in a relatively straight line. Then wrench away ,might take a few revolutions to get things tight enough to grab. ooh and make sure there is no grease or oil on the strap or flywheel.

 

[Rockytop20]

Ok what to do now? I used a harmonic balancer to split my case. I make another plate to pull it apart it seemed that the bolts lined up pretty good but the case got hung up on the countershaft which I had to lightly tap the crankshaft side with a block of wood to help get the gap even. It came apart so I hope everything is ok with it.
Looking at the crankshaft made me glad that I decided to split the cases. There is some metal in the case, which I believe is from the big end rod bearing. I am not sure how I am going to remove the crankshaft without the tool? Do you guys think it would be better to buy a whole pre assembled crankshaft, or try and just replace the big end bearing which is bad? I don't have a press so I might have to have some of the re-assembly done somewhere.

 

[whenfoxforks-ruled]

Check out wiseco, hotrods and oem. Some models complete cranks are not available. I like Forward Motion for crank rebuilds, if you need to go that route. OEM Kawasaki parts are crazy priced, more than 250? Rebuilt and shipping is way less.

 

[Rockytop20]

So would you go the complete route rather than trying to replace the bearing on the one I have now? How can I remove the old crankshaft without a press or that tool they have. Hit it with a hammer? Thanks for all of your help on this.

 

[whenfoxforks-ruled]

Hell no! If wiseco or hotrods has a complete assembly, jump on it! They have complete engine, or just complete bottom end kits for even cheaper! I think I ran across on kdx's, that they only offer rod kits, you would have to send it off to be rebuilt, is a lot cheaper than the 450 dollars that Kawasaki wanted for a new crank, thats ridiculous, most are around 250 dollars! For 250, its not worth rebuilding. On the side that the crank is stuck in, set up the balancer and push the crank out, piece of cake, the less you use the hammer, the better off your engine is! Tapping on the counter shaft is a given. Unless you make your own case splitter. The motion pros price on their splitter is pretty high. You could buy a piece of aluminum and 2 clamps pretty cheap. And the harmonic puller does work. If you warmed up the bearing with a torch, the crank would probably fall out.

 

[Rockytop20]

Ok, so I am ready to put it all back together, got a new crank assembly top end sent off to be repaired. I have decided to try to put the bearings and crank in with the thermal expansion/ contraction route. My question is how can I apply enough heat for this without warping or melting the oil seals?

 

[Patman]

freeze the bearings or better yet use dry ice which is faster and colder. Heat the cases in the oven or with a heat gun, maybe a torch if you feel like you can pull it off without making a puddle of aluminum out of them.

 

[whenfoxforks-ruled]

If you have one of them stupid set ups that require the seal to go in before the bearing? You should not be getting the engine hotter than its normal operating temperature to ease bearing installation, imo. A case at 170 should not melt the seal? Thats as low as my wives oven goes! Don't make me try it on an old seal first. Warming the cases is not in all the manuals, it just makes it easier. Setting them in the sun would help over sitting in the shade. Most drive in pretty easy as long as you keep it square to the bore, and pound on the races.

 

[Rockytop20]

Yes, The seal has to be put in before the bearing. I dont have a press, so I am gonna see if the bearings and crank will pretty much fall in place with the heating/cooling method like I have read on the internet. I think the engine temp probably would eventually get up past 170, so maybe those seals can handle some heat. Getting the crank in is going to be the difficult part I think. Thank you for all your help!

 

[Rockytop20]

I had to have the crankshaft pressed in because the heat method wasn't working for me. Now I picked up the bottom end and the crank is not as easy to turn as it was before I tore the thing down. The alignment looks ok, and the shop that did it said to lightly tap it with a hammer and see if it would get better. I did lightly tap with a hammer and it does not spin any more free. They also said it could just be due to the new bearings not being broken in? Any truth in this?

 

[whenfoxforks-ruled]

Nope, it will fail again soon! Is the space between the crank halves and cases the same, centered? I use a set of c clamps to pull the cases together, directly on the case to frame mounts, no heat or cold. If the crank needs to move over, tap it with a dead blow or wood mallet.

 

[Rockytop20]

the spacing between the crank halves looks to be the same. It doesnt feel like it is seizing up on anything though.

 

[whenfoxforks-ruled]

Them crank halves have a tolerance of .002" measured at a right angle to the rod. They have to be parallel. The thrust washer clearance at the big end? Bearings properly seated? Seals are not to far in? Most all the dimensions are checked with a feeler gauge, not eye balled.

 

[kx2502009]

my kx has 2 holes on the flywheel and i just threaded the holes and attached a harmonic balancer puller with two of my case bolts and it pulls right off every time it will also work to pull the cases get a puller and find 3 long bolts to thread into the stator holes run them in all the way and it should pull it right off its easier with a impact wrench but if there is shavings in the bottom end either your rod bearing in gone and if there is shavings down in the case then the shavings went threw the bearings and eat them up