RZ/RD 350 & Misc. 2-Stroke Tech BBS

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PostPosted: Wed Jun 13, 2018 2:45 pm 
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Joined: Sun Sep 16, 2012 7:10 am
Posts: 205
Location: gold coast Australia
I have been cleaning up my 4l0 engine parts ready for re assemble. I noticed a small lip on the bottom case half where the left side inner crank crank bearing sits. (Adjacent to labyrinth seal). There is also a small lip to the outside of the outside crank bearing. I have checked over some other cases i have and none have this lip (indent). The top half of the case is good. This engine was running a few weeks ago and there was no binding on the crank and the crank has been checked and is still true. looking at the cases it shows evidence of the other inside (right) crank bearing maybe being slightly loose, causing some chattering? Any tboughts on this gents?
I now have a spare set of good cases, all be it wrong engine number. Should i be looking at using these cases instead. ImageImage

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Last edited by graham heise on Thu Jun 14, 2018 7:09 am, edited 1 time in total.

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PostPosted: Thu Jun 14, 2018 6:46 am 
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Location: gold coast Australia
Had my lc crank trued today. show'd the crank cases to the guy. He said he's seen to many cases like it, could pull the crank out of true. Recommended i use the spare cases.

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PostPosted: Sun Jun 17, 2018 4:26 am 
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Joined: Mon Mar 03, 2014 8:44 pm
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Location: Alberta, Canada
Graham, you could always bolt the cases together and have them measured for tolerance. That would give you a better idea.

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PostPosted: Sun Jun 17, 2018 7:17 am 
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Location: gold coast Australia
what we be the tolerance? Maybe i could have used them but i decided to go with the spare cases. i completed the rebuild today, been through 5 heat cycles and all seems well.

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PostPosted: Mon Jun 18, 2018 3:57 am 
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Location: Alberta, Canada
Good work.

As for clearances, I'm not sure what the specs are. The machinist in me says 0.0005", is the standard bearing fit. Yamaha should have a spec somewhere. Anyone?

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