DF90 Low Compression #4

[Sirfishalot]

I have a less than 100 Hour 2005 DF 90 than has compression of 160 in number 4 cylinder the three other cylinders are over 215. I have run and ran a decarb and the compression will not rise. The oil is clean without water and no water on the spark plug. What else do i look for?

[Moonlighter]

Were the valve clearances checked and, if necessary, shims adjusted at the 20hr and 100hr service checks?

If not, get that done by your dealer as a matter of priority.