Cylinder/Piston Clearance

2 replies to this topic
  • wweagleflyer

Posted February 22, 2013 - 12:11 PM


I have searched the forum for cylinder fit/wear topics, but did not quite find what I was looking for. I have measured my cylinder very carefully ( I have access high end inspection equipment ) and found the cylinder diameter to be 3.7408 to 3.7411 (absolute max and min readings). My piston to cylinder fit is 0.003" (diameteral) and the manual gives a limit of 0.004", so I should be good. However, the manual seems to say that the cylinder should be replaced if the diameter is greater than 3.7406. The manual gives a diameter range of 3.7402 to 3.7406", but I can't tell for sure it the manual is quoting the range of new parts or if the maximum limit is 3.7406". If the piston to cylinder clearance is within the allowable, is there any reason I would have to change the cylinder even if it is a bit over the limit?

A copy of the relevant manual page is attached.


Attached Thumbnails

  • ManualPage.png

Edited by wweagleflyer, February 22, 2013 - 08:04 PM.

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  • grayracer513

Posted February 22, 2013 - 05:01 PM


The cylinder needs to be measured first in two places, the top, above the maximum point that the top ring reaches, and again near the bottom. These two numbers should match, and because there is virtually no wear in these two spots, it will tell you what size the cylinder originally was.

Then, it should be measured about a third of the way down, front to back. (It's worth checking in a few spots) If this measurement exceeds the others by over .002", replace the cylinder.

  • wweagleflyer

Posted February 22, 2013 - 08:10 PM


Thanks for the information. None of my measurements (top, bottom or center) differ by more than 0.0003", so I am good. It is amazing to me how little these cylinders wear.

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