Prepping a set of KX500 engine cases for rebuilding

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Seals aren't the only place for a potential air leak.
This is a troubled spot pointed out by Motorrad.
A small punch, cleaning, patience, cleaning, cleaning, cleaning, and some J-B Weld will fix this area up nicely.
Good vision would also help...

PUNCH CLEAN UP.JPG (40.94 KiB) Viewed 7398 times

Remember, if there is any oil or debris, J-B Weld will not stick and you've just wasted your time

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Here is the same view after clean up with a stainless steel wire wheel and carb cleaner.

PUNCH CLEAN UP -.JPG (40.75 KiB) Viewed 7397 times

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Nice!
Hope mine hangs in there like that

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I just discovered some new information on raw aluminum.
I'm sure some of you probably know already but there may be others that can benefit from it.
When I scuffed up the surfaces in preparation for the JB-Weld I didn't put the JB-Weld on right away.
In fact, I cleaned them up with some carb cleaner and let them sit overnight.
The next morning I noticed that the aluminum was already a little darker and not as shiny as it was when I first cleaned it up.
So I did a little research and it turns out that the oxygen in the air will start causing the aluminum to oxidize almost immediately.
From what I found, within an hour a skin can develop which will inhibit the bonding of the JB-Weld to the aluminum.
It may not be much but why take the chance?
So I cleaned mine up again before applying the JB-Weld.

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Here is how my cases looked after applying the JB-Weld.

kx500 engine case jb-weld 1.JPG (27.51 KiB) Viewed 7686 times

kx500 engine case jb-weld 2.JPG (21.35 KiB) Viewed 7686 times

Not the neatest job of applying the JB-Weld but I think it will work.

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Another thing that may help you is the tools that I used to clean the cases up.
Besides the punch I used a wire wheel (Left).
However, I felt as though it may have left too smooth of a surface so I used a small cutting tool (Right).
Man, did that do a quick and nice job of cleaning.
Because of the radius shape it was easy to get into all the nooks and cranny's.
A word of caution.... This thing cuts QUICK!!!

kx500 engine case jb-weld 3.JPG (26.92 KiB) Viewed 7686 times

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Had to fix the tower for the counter sprocket guard
So I got a piece of 1/2" round stock, drilled and taped it, also left it long.
Chamfered the angled end.
Ran a bolt through it to hold it all together.
Also, I ran a bottom tap all the way to the bottom of the tower hole as there was very few threads left.

tower fix.JPG (20.72 KiB) Viewed 7684 times

Then I took it next door and had my buddy weld it up for me.

tower fix -2.JPG (16.1 KiB) Viewed 7684 times

Once it was welded, I removed the bolt, ground the tower to the correct length, countersunk the end and cleaned up the edges.
I won't grind the weld down to clean it up because there is very little penetration and I don't want it to break off for no good reason.

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Some guys drill and ream the main bearing oiling holes to .250".
I like to stay around .180" - .200" as the material is pretty thin there..

pre-oil.JPG (42.21 KiB) Viewed 7646 times

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Since this was originally wrote, I invested in a vapor blaster and it was one of the best things I have done..
Now our cases are amazing
And no media impregnation...

KX GURU RACING 1992 KX500 SNOW BIKE ENGINE BUILD FOR BRENT 147.JPG (361.21 KiB) Viewed 6053 times

KX GURU RACING 1992 KX500 SNOW BIKE ENGINE BUILD FOR BRENT 148.JPG (353.02 KiB) Viewed 6053 times

There is also some other things that we could discuss such as the cylinder mating surfaces and the studs.

Again, thanks goes to Motorrad for his patience in tuning me up on many of the things you saw in this thread.