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Discussion Starter · #1 ·
We all know someone who has a busted out drain bung on a 420. Overtighten the drain plug and CRACK, the little piece up there breaks off and your crankcase is junk.


Looks like Honda redesigned the crankcase. Saw this on an ebay posting today for a 2012 Rancher crankcase.


Look closely at the drain plug.
 

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Nope. They're all like that. I have 4 420 engines from various years all disassembled. All that little stub gives you is a few extra threads. But that soft aluminum can still be stripped/cracked by overtightening the drain bolt. Can rescue the crankcase by tapping 2 sizes up but have to be very careful, there's not a lot of extra meat on the sides of that stub to re-thread. And if the crankcase is cracked from overtightening, well, then it's a decision of whether to tear apart the engine and change out the crankcase section or find some type of product to "repair" it as best as possible. Aluminox was a good product, haven't seen it around in a while, but they must still make it or something similar. It's an epoxy resin mixed with aluminum powder, something like JB Weld.
 

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Discussion Starter · #3 ·
The early ones had threads at the bottom, then a gap, then a ring around the top that was threaded. If you overtightened you would break the "ring" at the top and it was done.

The crankcase I pictured has threads going most of the way around without the ring at the top.

Probably still not a bulletproof design by any means, but better than the original design.

http://www.hondaatvforums.net/forums/539754-post16.html
 

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haha, I know for a fact the old design sucks !!!..lol. what they SHOULD do ?, is make that bottom area thicker for one , and then make it solid, with a hole at the case level for oil to drain, that's how I would make them.
 
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