Simonini Specifics

10/02/2007 Thanks to Adam Bell for the genesis and initial information on this page. This information is being integrated with the general troubleshooting.

See also the Chapter 12 article on Getting Parts.

Adam Bell of AZhangar.com shares some of his experiences with the Fly Simonini motors and trouble shooting problems.

#1 most common problem, easily fixed.

Electric start isn't cranking authoritatively, most pilots assume their battery is going and re-charge it often or the night before a planned flight. The problem isn't usually the battery, it's the carbon buildup plugging the decompression port that allows pressure to flow from the inside of the cylinder to the exhaust. When pressure from inside the cylinder cannot pass through to the exhaust system, turning the propeller becomes a bit harder and your battery will not appreciate this over time.

Fix:

1. Make sure master/ignition switch is OFF.

2. Remove spark plug wire.

3. Loosen the cylinder head bolts in an opposite, diagonal fashion, don't take them completely off yet.

4. Secure the motor in position with a tie strap or piece of rope etc so that when the top motor mount bolts are removed, the motor remains in position and does not fall rearward. If this step is omitted, unnecessary stress will be placed on the lower motor mounts and other components. Run the strap from the top of the frame on the left of the motor as viewed from rear, (not cage) around the cylinder (below the head) and to the frame on the right side of the motor. Make sure it is snug enough to keep the motor where it is once the top mount bolts are removed.

5. Remove the two top motor mount bolts from the front of the frame with the alan wrench that came with your maintenance tool set. If you don't have it, use a metric alan wrench that fits the bolt. It's best if the alan wrench is a bit long, this gives you better leverage and makes it much easier to get to the bolts. These must be removed first in order to get the cylinder head off the motor.

6. Loosen the 4 cylinder head nuts and Remove the cylinder head.

7. Locate the decompression port on the left side of the cylinder wall about an inch or two down. Make sure your piston is not all the way down, keep it just a bit below the decompression port so that debris does not enter into the motor via the cylinder. Use a small drill bit and electric drill to ream out the carbon build up in the decompression port. Make sure the drill bit is just smaller than the decompression port hole. The hole goes diagonally from the cylinder wall into the exhaust port. Drill at a low RPM and slowly as you feel for the path of the decompression port hole. Once you've got it, run the drill bit back and forth a few times to ensure a nice, clean port hole.

8. Now is a good time to clean up any carbon deposits or build up on the top of the piston and cylinder head. Remove the spark plug, clean and gap. Use some steel wool or lightly sand with 150 - 200 grit sand paper, taking care not to really scratch things up.

9. Put it all back together and take care in ensuring the cylinder head is fit properly down on the cylinder with no gaps between the head and cylinder. Tighten all nuts and bolts to specs, insert the spark plug and tighten, put the spark plug wire back on, remove the securing strap and go over everything to ensure all nuts and bolts are secure. 

10. Your motor should start like it is brand new! This procedure should be repeated about every 25 - 35 hours of run time to ensure reliable performance of your Simonini motor.

Sudden Power Loss or "Blip"

Pilot is flying around happily and is startled by a sudden loss in power for an instant, a kind of burble that may occur once or a few times during a flight with power at full or just shy. It really seems like an ignition type problem at first or a loose wire vibrating on a connector etc.

If you have the old style fuel primer bulb, the check valve components inside may be loose fitting, cracked or may have fallen out into the bulb. Any of these scenarios can cause intermittent power problems or a complete loss of power during flight. Take your primer bulb off and inspect for loose or damaged valve components.

The fix can be one of many:

1. Buy a new style primer bulb that is standard on Fly Products units 2006 and newer. 

2. Find another type of primer bulb that can be used with auto or aviation fuel and can handle the intended mission.

3. See if you can get parts to fix the damaged valve components in the bulb.