Splitting the Case of KX85

[Chance3]

My son has lost a piston in his 2004 KX85 and there is metal in the crankcase oil. My feeling is that the case needs to be split to recover and miscellaneous metal pieces. Is this a complicated procedure? We have successfully rebuilt top ends many times however a little nervous about opening the bottom.... Any suggestions or advice would be greatly appreciated.

 

[skiboyracing]

Nothing to it.. Buy yourself a good service manual. For your flywheel rent a 3 jaw puller from autozone (it's free) then on the clutch side use an air impact to remove the center nuts. Then when the clutch and everything is removed and your ready to split the case, build a box out of 2x4's and lay the engine on the box with the clutch side down. Get a harmonic balancer puller or steering wheel puller and install it over the flywheel side of the crank case. Get yourself longer bolts to thread down through the puller to the stator bolt holes and torque the puller making sure you have grease under the puller where it meets the crankshaft.. it will split the case. The only place I used outside help was to remove the crank from the right side case. Cost 5 bucks at a local shop. For bearing replacement, heat the empty case in the oven or set it in front of a salamander heater. once hot tip it over and bearings should fall right out.. the mains may need tapped with a socket and hammer. For the install, heat the case up, pull the bearings from the freezer and drop them in.. when the case cools they are pressed in. For the crank shaft, first install it in the right side, find an alluminum slug or something that will fit into the center of the main bearing. heat it with a torch being carefull not to over heat it and turn it blue. once hot drop your FROZEN crank shaft into the bearing.. it will drop right in. Do the same to the left side cover and bearing, but this time have a block of wood and a mallet ready. Place the cover with the heated bearing over the crank and tap the two cases back together. Nothing to it. And when you reinstall all your gears and clutches to the side of the case you can use a penney to bind the gears to torque the bolt. But it will cost you $.01 as it will eat your penny. :) Give it a try, it'll be a good learning experience for you and your son. I assume your doing this to replace your crank shaft. Otherwise I would flush it out with solvant and call it a day.

 

[Chance3]

Actually I believe that the bearings are ok, it just that we have found metal in the oil after the piston let go and would like to be sure that there is not any residual pieces left that would do more damage. Do you recommend just rinsing with solvent? If what do you recommend for solvent? Thanks for the help.

 

[skiboyracing]

you found metal in the transmission oil? If so the crankshaft is completely sealed from the tranny oil so you shouldn't have any issues with metal from a cylinder/crank in with the tranny oil you drain from the bottom of the case. Unless some how you put a hole in the case. It's hard to give an opinion on what you should or should not do since I can't see what you have going on, but if you think your bottom end was fine then I would fill the crank shaft up with kerosene or fuel oil and flush it out and rotate your crank shaft around a couple of times. Take the rod with very steady hands and make sure there is no up and down movement, a bit of side to side is fine, but no up and down. Also, when you flush the crank shaft out, you can then make sure none of it goes into the tranny. If so then i would look for a seal or gasket leak. If you have chunks of metal, not just clutch residue in the tranny oil, then you may have to do like you were thinking and split the case to see what is going on. Make sure the chunks weren't off the clutch basket or something as well.. Basically investigate and be sure you know what the metal you found was and how it got there. Then decide what to do about it. I personally wouldn't split a case without a new crank or rod assembly and bearings through out it. To much work not to spend a couple hundred bucks to make it new while your there. But that's just me. Make sure to post how you make out.

 

[Chance3]

Maybe I am a bit more in the dark then I thought. If a piece of the piston came apart wouldn't the metal pieces drop down into the crankcase? This is the oil that was drained and it felt like there was some metal fragments in it. Sounds like the transmission gears are not part of the crankcase area?