I purchased a ST 61 ABC new this summer. To date it does not seem to develop the power I expected. It starts, idles and transitions fine, but it just does not seem to get up to RPM very well using either Omega 10 % or Omega 15% fuels. All my other engines are running out of the same fuel bottles just fine. My question is how long does it take to break in one of these engines? What RPM Should I expect turning the 11 X 7 prop recommended in the specs? I did all the normal troubleshooting like removing and sealing the backplate and checking for air leaks around the carb base, etc. I've been in the hobby four years.

I was very careful to initially break it in per the instructions. It was run rich but not four stroked a few minutes then shut down and allowed to cool and then restarted and run over and over again for at least four tanks of fuel before it was mounted in the plane.

I have it installed in a 60 size Pattern trainer that weighs about 7 pounds, maybe 7 1/2 pounds. When it takes off it acts like its dragging the airplane into the air. Once it gets to altitude and starts down, the RPM seems to come up some. I have a MAS 11 X 6 Prop on it because it won't turn an 11 X 7 well at all on this plane. It is set up with the stock muffler, there have been no modifications. I don't have exact RPM numbers but could get them if it would help.

Frankly either of of my 46 size engines will turn an 11 X 7 prop better than this guy is doing. I have a ST GS 40 that runs great which is the reason I decided to get this one for this new airplane.

Your help here is appreciated.

John Mecalo