Splitting 2 stroke cases

GaryInVA

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I have a 1979 Yamaha IT400F that my son and I are rebuilding. We just pulled the engine out of the frame. Next comes splitting the case so that we can get the crank rebuilt. I need a case splitter and am looking for something inexpensive. Anyone have any recommendations?
 

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Vincenthdfan

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Case splitter?, they come right apart, once the bolts are out.
No, they dont.

The main bearings on the crankshaft are press fit on the crankshaft and into the case halves.

Yamaha makes special pullers for this but if youre handy you can use pieces from a steering wheel puller and a piece of square tubing with holes drilled in it. There are corresponding empty holes in the case halves that you can thread the puller bolts into while you bear against the crank and gently tap around the edges of the center cases.
 

jpdevol

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GaryInVA

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I spent the night watching videos and searching the web for case splitters. Had one similar to that bookmarked. Was also looking at Tusk tools on Rocky Mountain ATV. Have never used a crank puller like that before. We always, back in the day, froze the main bearings, heated up the case and dropped it in, then froze the crank, heated up the bearing in the case and assembled the two halves. That puller looks a lot easier.

A reason to buy more tools. Yeah!
 

toglhot

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I've pulled a quite a few two stroke engines apart, singles and twins. Never had any problems. For the difficult ones that wouldn't split, I simply turned it on it's side and gave the crankshaft a few wacks with a plastic dead blow hammer. You just have to put something underneath to catch the lower case and crankshaft when it comes apart.
 

mrtwowheel

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I just split the crankcase on a '81 CB750C, first and only crankcase that I have ever split. I did this with the engine upside down supported by a half inch plywood box and a long carriage bolt through the box and rear motor mount. Three rounds of banging with a rubber mallet and a final blow with a short 2x2 on a corner, the only corner to possibly move it, and it easily split with everything staying in place, even the crankshaft bearings. Asked for some heads up on the "non-happening" 750 forum, maybe the second time I've ever asked for help, and no one came around. Between the Honda manual and the Clymer manual I think it all came out quite well. Would gladly do it again without special tools.

I understand that we're talking about different types of bearings.
 
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Vincenthdfan

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I just split the crankcase on a '81 CB750C, first and only crankcase that I have ever split. I did this with the engine upside down supported by a half inch plywood box and a long carriage bolt through the box and rear motor mount. Three rounds of banging with a rubber mallet and a final blow with a short 2x2 on a corner, the only corner to possibly move it, and it easily split with everything staying in place, even the crankshaft bearings. Asked for some heads up on the "non-happening" 750 forum, maybe the second time I've ever asked for help, and no one came around. Between the Honda manual and the Clymer manual I think it all came out quite well. Would gladly do it again without special tools.

I understand that we're talking about different types of bearings.
Yes, horizontal splitting cases are a god send compared to vertical splitting cases...much, much easier.
 
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