Mystery part in crank

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AndyCapp
Mariana
Posts: 29
Joined: Fri Jun 10, 2011 10:30 pm

Mystery part in crank

Post by AndyCapp » Sat Aug 20, 2016 9:33 am

Crank_MysteryPart.jpg
My big end has expired after only 8000 miles. On removal of the two plugs from the crank web I found this wedged in the middle. Ok, this explains my cranks early demise, but what is this part and where did it come from? It appears to be spring metal.

Uncle Steve
Cucciolo - the Lil Pup
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Joined: Mon Aug 01, 2016 9:49 pm

Re: Mystery part in crank

Post by Uncle Steve » Sat Aug 20, 2016 1:09 pm

The only thing I can think of that looks remotely like that is part of the gear selector fork. Regards Steve

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AndyCapp
Mariana
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Joined: Fri Jun 10, 2011 10:30 pm

Re: Mystery part in crank

Post by AndyCapp » Sat Aug 20, 2016 10:39 pm

On thinking about it more, I came to the conclusion it's far too large to have found its way there from somewhere else, so must originate from there.
If this was placed directly in the middle, it would direct the oil flow around it - towards each plug. Without this, the oil would simply flow straight past. So I guess its important to have it in place. As mine is broken, any ideas where I get a new one from ?

wdietz186
888
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Joined: Sun Sep 10, 2006 4:40 pm

Re: Mystery part in crank

Post by wdietz186 » Sun Aug 21, 2016 6:19 am

Some cranks had a restrictor in the feed end to boost the feed to the top end. It was a roll pin [spring steel] that fit a few millimeters in from the end. Leave it out and read the article Kevin Bracken wrote about building his race engine[s] and improving the oiling system.

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