I have a seca 750 82 and it has been in storage for 2 years. When I took it out to start it was misfiring and I had to keep the choke open, even though it kept misfiring and dying. The tank was rusting with lots of rust inside, I cleaned and recoted the tank put new gas and with courage I took the carburator out and cleaned every part possible with a spray and reinstalled, the plugs where new and where black, clean it up and reinstalled, check the air filter it was good and after everything put together it started on the first start. It sounded great and smooth. I hope this may help you out.