How to safely split your motorcycle engine cases.

Bottom end tips and mods
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Sandblaster
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How to safely split your motorcycle engine cases.

Post by Sandblaster » Sat Jun 23, 2012 4:55 pm

Here is a problem that veteran engine guys will laugh about.
However, for the uninitiated, this can be an intimidating situation.
You need to replace your crank shaft.
So, you have removed your engine from your bike.
You have removed all the bolts, springs, snap rings, cylinder, linkage, ect from your engine.
Here is what your are left with.

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In this case, I used a 93 KX500 Engine.
Some guys will grab a hammer and start beating the transmission shafts to split the cases.
While this can in some situations work, you always take the chance of damaging your shafts, cases, gears, ect.
The solution is to buy, beg, or borrow a engine case splitter.
This one is a Motion Pro but there are many on the market that work just the same.

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#1 rule. DO NOT BE IN A HURRY.
Engine cases are expensive and can easily be broken.
Before you get started, take the time to clean the threaded areas carefully and even run a test bolt or chase the threads with the correct size tap if required.
Oil all the threaded rods, set nuts, and threaded holes.
Next, assemble your tool.
Slip the arms onto the main shaft.

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Then hand tighten the set nut.

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If bikes are for kids I'll never grow up.

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Sandblaster
Posts: 6313
Joined: Thu Jun 07, 2012 3:50 pm
Location: Eugene, OR
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Re: How to safely split your motorcycle engine cases.

Post by Sandblaster » Sat Jun 23, 2012 4:57 pm

Next, slip on the centering tool on the end of the shaft.

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Then run the threaded rods through the arms with the retaining washers and set nuts.
Try to spread them out as evenly as possible so that you get even pulling pressure on the cases.

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Hand tighten all the set nuts so that the center axis of the pulling tool shaft is in line with the center axis of the crank.
I know it's tempting to use a ratchet or a impact gun but please resist the temptation and use a hand wrench.
Yes, it takes a bit longer but your tool will last longer and you will not be as apt to strip the threads in your cases.
Once the bolts are snug and the axis of the puller is properly aligned with the crank, start tightening the main puller shaft bolt.
Within a half to a full turn you will usually hear the cases pop.

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Check the back of your case to make sure it is not pinching at the back while split in the front of the cases.
If that happens you may need to loosen all the bolts and move them around to get more pulling power on one end of the cases over the other.
Once again, do not be in a hurry.

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All done :-o
Usually it takes me about 10 minutes to pull all the tools out, split the cases and put the tools away.
Piece of cake!
If bikes are for kids I'll never grow up.

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