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motocrosschump

Splitting Cases Virgin..

7 posts in this topic

Is there any special tools that I need? Or any special things that I need to know. My 400 5th gear is shot.

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You'll need a flywheel/rotor puller to get the rotor off. An impact wrench would help with the crankshaft nut on the right side, and maybe the clutch/countershaft sprocket nuts, but is not really necessary - you can use a piece of soft metal (aluminium) in between the gears on the right side to keep things from turning while you are loosening them. The crank comes off with the left case (it's pressed into the left case crank bearing) so as long as you don't plan on changing the crank/main bearings you don't need any special tools. That's it, as far as I can remember from my engine teardown/rebuild. Oh yeah, a torque wrench for when you put everything back together.

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while your tearing into the motor,its a good idea to replace the crank bearings while your in there,TRUST me on this one,i have to tear mine back down as we speak because i knew i should have done it but i didnt want to wait for parts,plus mine were fine anyhow,i guess thats the price i pay for trying to cut corners.good luck :thumbsup:

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The crank comes off with the left case (it's pressed into the left case crank bearing) so as long as you don't plan on changing the crank/main bearings you don't need any special tools.

If you decide to replace the main bearings (a good idea IMO) you will probably need a press to install them, although I've heard folks do w/out by heating the cases and leaving the bearings in the freezer, something I do even though I have a press. I've not tried to put new bearings in a used case, but know that they damn sure won't go into a new set of cases w/out a press.

You can use a common steering wheel puller to reinstall the crank...

Before reinstalling the tranny parts, make sure all the splined gears move freely along the shaft, if the shaft splines got nicked at some point you will need to smooth them out so the dogs will positively engage. For the same reason make sure the shift forks are straight and move freely on their shafts and inside the shift drum.

You can verify that the tranny is shifting properly before you put the cases back together by operating the shift drum (you install the tranny in the left case and then put the right case on over everything).

Hope this helps.

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If youve never done it before you need to assess a few things first...you MUST have a manual, especially if its your first time doing cases. Keep things VERY clean and organized...put parts in labeled baggies and together in order of installation if possible. Use a digital camera to take pictures of things before you take them apart...you might need them later to figure out where the spare parts go! :thumbsup: The cleaner and more organized you keep your parts and work area, the faster it will go together...other than that, any tools(flywheel puller, Torque wrenches, etc) can probably be loaned to you by your local dealer...at least they let me borrow theirs!

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