Engine Preservation Exceeding of Maximum Admissible Exhaust Gas  Temperature Troubleshooting and Abnormal Operation Troubleshooting Engine Keeps Running With Ignition OFF Knocking Under Load Abnormal Operating Exceeding the Maximum Admissible Engine Speed Exceeding of Maximum Admissible Cylinder Head  Temperature 11-24 Reduce engine power, setting to the minimum necessary,  and carry out precautionary landing. Any exceeding of the  maximum admissible cylinder head temperature must be  entered by the pilot into the logbook, stating duration and  extent of excess-temperature condition. Reduce engine speed. Any overage of the maximum  admissible engine speed must be entered by the pilot into the  logbook, stating duration and extent of over-speed. Possible cause: Octane rating of fuel too low.  Remedy: Use fuel with higher octane rating. Possible cause: Fuel starvation, lean mixture. Remedy: Check fuel supply. Possible cause: Overheating of engine.  Remedy: Let engine cool down at idling at approximately  2,000 engine rpm. Problems of a more complex nature are best left to an engine  technician. The following are examples of engine troubles  and potential fixes. The information in this section is for training purposes  and should never be used for maintenance on the actual  aircraft. Only qualified personnel (experienced two-stroke  technicians) trained on this particular type of engine are  allowed to carry out maintenance and repair work. If  the following information regarding the remedy of the  malfunction does not solve the malfunction, contact an  authorized facility. The engine must not be returned to service  until the malfunction is rectified. As described earlier in the  text, engines require basically two essentials to run: spark  and correct fuel/air mixture. The majority of problems quite  often are a simple lack of one or the other. Follow an organized method of troubleshooting. This  facilitates the identification of discrepancies or malfunctions. If the engine is not going to be used for an extended period  of time, certain measures must be taken to protect engine  against heat, direct sun light, corrosion, and formation of  residues. In particular, the water bonded by the alcohol in  the fuel causes increased corrosion problems during storage. After each flight, activate choke for a moment before stopping  engine. Close all engine openings like exhaust pipe, venting  tube, and air filter to prevent entry of contamination and  humidity. For engine storage of one to four weeks, proceed  with preservation prior to engine stop or on the engine at  operating temperature. Let the engine run at increased idle  speed. Shut the engine down and secure against inadvertent  engine start. Remove air filters and inject approximately  3 cubic cm of preservation oil or equivalent oil into the  air intake of each carburetor. Restart the engine and run at  increased idle speed for 10–15 seconds. Shut engine down  and secure against inadvertent engine start. Close all engine  openings, such as exhaust pipe, venting tube, and air filter,  to prevent entry of contamination and humidity. For engine storage of engine for longer than four weeks and  up to one year, proceed with preservation prior to engine stop  and on the engine at operating temperature. Let the engine  run at increased idle speed. Remove air filters and inject  approximately 6 cubic cm of preservative oil or equivalent  oil into the air intake of each carburetor. Stop the engine.  Remove spark plugs and inject approximately 6 cubic cm  preservation oil or equivalent oil into each cylinder and  slowly turn crankshaft 2 to 3 turns by hand to lubricate top  end parts. Replace and re-torque the spark plugs. Drain  gasoline from float chambers, fuel tank, and fuel lines. Drain  coolant on liquid cooled engines to prevent any damage by  freezing. Lubricate all carburetor linkages using the proper  lubricates. Close all openings of the engine, such as exhaust  pipe openings, venting tube, and air intake, to prevent entry  of any foreign material and humidity. Protect all external  steel parts by spraying with engine oil. Reduce engine power, setting to the minimum necessary,  and carry out precautionary landing. Any exceedence of  the maximum admissible exhaust gas temperature must be  entered by the pilot into the logbook, stating duration and  extent of excess-temperature condition. •  Fuel—start by checking the supply (tank), fittings  (loose), filter (plugged), and float chamber (fouled). •  Spark—check for spark at the spark plugs.