I think Harry may have hit the nail on the head here... when I was changing the fluids the local small engine company I get my parts from said to use 80W140 gear oil in the tranny. I'll be replacing the 80W140 with the correct fluid soon as I can get it picked up and testing from there.
I agree the lines are small, but its only seeming to happen when the tranny is in gear.. I let it run at full throttle the other day for an hour and no issue till I put the tranny in gear... tiller/PTO was running the entire hour (to place stress on engine) without any issues.
-Original copper gas lines
-Coil & condensor seem to be good becuase as soon as I take it out of gear/put in neutral the engine returns to regular operating speed.
-no oil traces or head gasket issues
this happens whenever its in-gear (not in neutral) doesnt matter if clutch is in or not.
I have an IH Cub Cadet 122 w/ the Kolher 12HP motor and manual H transmission that I purchased back in April.
I've been fixing it up, tuning this or that here & there, new oils/lubes, new belts, etc. Unit was sitting for a couple years before I purchased it.
I seem to be having trouble after...