JD F935 Yanmar 155# compression?

[Himark]

I have a late 90's 935 1800 hours and have been experiencing EASY start but will run rougher than crap for the first 3-5 minutes then is smooths out. (similar to low compression problem) BUT if you shut it off and restart it right after it smooths out it goes back to rough running for another 3-5 minutes. <--------a low compression cylinder after warming up wouldnt do that. Go to engage mower and it will nearly kill it. It has LOW power. Oh I also pulled the oil cap while running and it has little to none blow by...So the obvious was to run compression and I was expecting a dead hole with one marginal but what I found was even # across the motor 155, 157, 159. Is it possible that it jumped time or has a valve problem? Anybody have any experience here that could lend a hand?

[davkir]

I don't know anything about an F935, but I think some of them use a Yanmar diesel.
The specs. in the manual for my 24 hp. Yanmar 3TNV76, call for 498 psi @ 250 rpm cranking speed and a minimum of 398 psi.
Hope this helps.