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How to check bottom end play?

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I changed my piston the other week and just want to double check how you check for bottom end wear, what I did (which was what I was told) was basically checking for up and down movement of the conrod on the crank which there was practically none at all, there was a tony bit of side to side movement but no up/down or in and out depending on how you want to describe it,

Is this the right method?

Just out of curiosity how much bottom end wear would you expect after at a guess 150hours of use overall? I know it's hard to gauge depending on riding

Edited by pwalker

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Your manual will give you all the specs for axial rod movement, crank run-out, rod-to-thrust-washer clearance, etc.

 

My KX250 OEM lower rod bearing was toast at 150 hours. The Hot Rods crank in it now has over 200 on it and is still tight.

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I am just finishing up a complete rebuild on my 2001 yz250...when I first took the jug off the crank had tons of up and down slop in it...which is bad. The lower arm bearings were hammered flat, luckily that was the worst of it. From what I've read/heard/seen you don't need to worry about side to side movement (since the cylinder keeps it centered) but up and down is bad news bears. If you have even a little I'd probably crack the case open and swap the crank out...sucks but is better than wrecking your stuff beyond repair...just my $.02

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There are specs in most service manuals that list the tolerances for "side play" (horizontal clearance at the big end) and actual bearing clearance, both.  With most Japanese bikes, since the correct bearing ("vertical") clearance is so small, the measurement usually given is for the amount the small end can be rocked from side to side without it sliding on the crank pin at the big end.

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