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Thursday, January 10, 2013

Philosophy of engine building / RG500 Stator Installation


I have recently proved to myself once again that it is possible to work too fast building an engine.  

A mistake which would have taken another minute to carefully avoid during construction can turn into twenty hours of consternation and repair work later on.

OK, here's a recent war story from my RG500: I skipped looking in the manual at the stator mounting page.  Seemed fairly simple, just three screws after all.  Didn’t see the notice to use locktite.  Didn’t use locktite.

Turns out stators are under lots of periodic stress as the magnets in the rotor whirl around and electricity is generated.  Lack of locktite resulted in stator becoming loose.

Loose stator rattled around for a while.  Until a few windings wore through against the rotor and shorted out.  Causing one of the three yellow stator output wires to break and the stator to fry. 

Fifty twisty miles from home on the Coast Highway while zinging along in 6th.  Sudden and complete spark disappearance.

Talk about a buzz kill.
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Here's the fried stator:

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Here's the RG500 Shop Manual item about installing the stator.  I don't know what Thread Lock 1342 is.  I used Red Locktite.  It's OK to use Red on small threads, it's only large things that need to be heated for disassembly.

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Here's the loose screws.  Looks like they were rubbing against the inside of the rotor for a while.
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It would have been a lot easier and less time consuming to have read the manual and used Locktite than to have to remove the stator again.  Here's a pic near the end of the job with the replacement stator in place:
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It is important to pay attention to every word in a shop manual.  When they say "Route the stator lead wire properly" they mean it.  Suzuki cast a little post and threaded a mounting hole for a bracket just for this purpose.  After a previous rebuild I found out that if this bracket is left out the wire will rub the rotor, wear through, and cause the bike to stop running.

I made my own bracket.  It's in the top right of this image:
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Suzuki wants lots of Locktite around the stator and rotor:
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Factories are vary sparse with the words in shop manuals.  Each word is important.  Read it or weep ;-)
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Of course, there is another possibility.  Maybe I verified the words of an old AMA Pro friend "Never put a fastener on part way."  It is possible that I put the stator screws in finger tight then never made another round for final tightening.

Which ties in nicely with my opening statement about how important it is to be patient while building engines.




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