A couple of issues have recently come to light regarding the EVO 58 from our service department at Horizon this past week.

1. There are occasional instances where drawing fuel to the carb is very difficult, even with the choke closed. We have discovered that with some of the walbro carbs included with our 58cc engines, the sprung loaded automatic mixture control needle under the vented plate (opposite the pumper side of the carb) will occasionally stick, almost like there is a preservative used in the manufacture of the carb. If you attach a clean piece of fuel tubing to the aluminum 90 degree elbow and blow lightly into this chamber, you will free the sticky needle and you should see fuel readily move through the carb. This usually only needs to be done once.

2. The one common cause of apparent low power output is a hi-side needle setting that is too lean. What we have discovered is that while the base line settings for the high side (1 turn, 10 minutes, or not quite 1-1/4 turn) were correct when we first introduced the engine and published the manual, it does seem that the proper new baseline setting for the high side is 1 turn 45 minutes (or 1-3/4 turn) from closed. This will put both needles at the same spot to start the engine and adjust from there. We are in the process of updating our manuals to correct the error.

The two engines under debate are indeed identical engines, as we at Horizon have been boasting all along. You should easily see numbers in the 64-6600 rpm range with quite a few different aftermarket mufflers. With the cannisters we did indeed test the EVO 58 at 6900 rpm on a Mejzlik 24 X 10 prop. The actual best torque curve for the engine is in the 6100-6400 rpm range, yielding a very flat response. For performance that requires the maximum torque (not necessarily the maximum horsepower) prop your engine for this range and we think you will be astounded by the hovering power available to you. We actually were very happy with a wooden 26 X 8 prop turning in the 6300rpm range on one of our 33% Edge 540's Awesome performance.

If anyone is still having issues such as very low power output after trying the above suggestions, please don't hesitate to contact our service department and/or send in your engine for evaluation. That is what our warranty is out there for. We are ultimately interested in your long term satisfaction with each of our products.

Pete Bergstrom
Category Manager
JR Radios and Engines
Horizon Hobby Inc.