914 Not Starting after an Year

hi Mehdi

After that long a time you will need to remove the carburetors and have them cleaned.  Fuel evaporates and leaves behind gums that plug up the jetting and contaminate the fuel system.  Replace the fuel filters also and be sure to clean the finger screens in the inlets of each electric fuel pump. 

Be sure to drain the old fuel and replace with fresh also. 

Cheers

I would remove a plug from each cylinder and see if there is any sign of fuel. I would then connect the plugs to the HT leads and rest them on the block. With the ignition on, crank the engine and check that you have a spark across the electrodes. It is unlikely that you have lost compression in all cylinders, so the above tests should allow you to isolate your problem and then you can proceed accordingly.

Sure, Will try doing this 

Mehdi

Be very careful if you are trying to "see" spark on a CDI engine.  The spark is very fast and difficult in any bright light.  In addition if you remove, for example, the cylinder 1 top plug and cylinder 2 top plug they fire from the same HT coil.  If both plugs do not ground you can get a backfeed that may damage the CDI box internally.  CDI in general has to have the plugs grounded at all times.  In shop work this is done with a ground strip where the testing involves screwing the plug into the grounded strip to be sure that they will fire.  Laying a plug on the cylinder head is not a good method to ensure grounding.  

Cheers