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Crankshaft play

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I pulled my piston out yesterday to measure it for tollernace and noticed that my Rod has left to right play in it...a fair amount.  Is that normal?  The motor is still on the bike so I havent split the cases, and didnt plan on it, but may need to now if what I am seeing isn't normal. 

Edited by WarHammer0106

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They normally have some play in them...spec calls for .012" to .030".

It's hard to gauge big end rod wear...the thrust washers only wear below the outside circumference, so they may measure correct when in fact they are in the process of failing.

The only way to know for sure is to replace it...

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They normally have some play in them...spec calls for .012" to .030".

It's hard to gauge big end rod wear...the thrust washers only wear below the outside circumference, so they may measure correct when in fact they are in the process of failing.

The only way to know for sure is to replace it...

I havent seen any gold/bronze glitter in my oil when I change it.  I got the bike in Feb 2014 and have changed the oil 3 times.  I hate to put any pressure on you Paul, but if it was you would you split the case and be sure, or if I havent been seeing any thrust washer shavings in the oil then I am probably ok?  The bike has had an engine noise since I bought it and it sound like its in the top end.  The piston that I just pulled out of it was out of spec by a good bit.  I was hoping that was the sound that I was hearing.

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No gold is a good sign, but that doesn't guarantee anything.

If the piston was under spec, piston slap was likely the culprit.

If this is a bike that will be raced or used on long haul, Baja style trips, I'd replace just for piece of mind.

If it's not likely that it will ruin a race season or leave you stranded 100 miles from civilization, you may be able to take a chance.

Only you know if saving the $ 300 for a new one is worth the chance.

 

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Thanks Paul!  I am not doing any big Baja style rides on this bike.  I will consult my repair manual and find out if I am in spec or not.  If I am not in spec is there a reason that I should use or not use an OEM crank and rod?  I do appreciate the knowledge that you and the rest of the forum share.

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You can NEVER go wrong with OEM...on almost everything except that damn front tire. :)

In this case you can also use the Heavy Duty Crankshaft from Hot Rods...it is as good as OEM (if not better...)

ALWAYS stay away from Wiseco cranks, even if they are FREE!!

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Just measured the crank...it's well within spec. I got a .012" in pretty easy but a .017" is where I got a little drag from my efforts. Not sure why I thought it was a bit loose but it's surely not. I will leave the motor in the frame and not split the case.

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I  thought Crankshaft play was a sexual term.

We know you love you X Kah Ran Nee but that is taking it too far.........................

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