Cleaning decompression hole on Simonini engine:

After 70 - 120 of flight hours you may notice compression increase on you Simonini engine. It will manifest it self by starter motor barely able to turn the prop over or general difficulty to turn over the prop. If this is the case, you will have to clean the decompression hole. This is how to do it.

Turn your paramotor frame upside down and secure it. (make sure you close the tank nice and tight, you do not want to spill your fuel)

Undo the two silent blocks attach to the engine head. Then undo the 4 bolts holding the cylinder head down.

Take the head off. Note the small arrow engraved on piston that is showing the orientation of piston with respect to the exhaust port. It should always point to the exhaust side of the crank case.

Here is the decompression hole filled with carbon. 

Take a 2.5 mm drill bit and bore at 45 degree angle to clean the hole. Make sure that your drill bit does not slip as not to scratch the inside of the cylinder head. Use a spoon to collect all the carbon and possible metal shavings.

Install new O ring gasket and re torque the head to 22 NM. Attach the head silent blocks to the frame, slip on the spark plug wire and you are done. 

Good luck cleaning you hole ;-)   Andre

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