Age and info

Category: 2 Stroke Technical Questions one month ago

Have a 503   Serial number 3561689.

Trying to find out year of this engine and a manual that I can download. Also looking for a starter that will fit this without breaking the bank.  I’ve tried online searching for info and manual but cant seem to locate one. I know about the ones you see online for starters but not sure if any of these will fit. Doesn’t matter if it protrudes into firewall. Hope some of you out there can help. I know its an older engine and its in a Himax ultralight i just bought. Has pull start but want to switch it to electric. 

  • Re: Age and info

    by » one month ago

    3561689 was produced 02-July-1985

    Unfortunately, that  is so ancient that there is zero additional information in the current factory database (not even a confirmation of model number / engine type!).


    I assume you have already read the 'modern' 503 manuals (found at https://www.rotax-owner.com/en/support-topmenu/engine-manuals#447-and-503-engines)


    Maybe have a look at the older historical version found here: https://www.rotax-owner.com/en/support-topmenu/engine-manuals#2-stroke-historical-documents


    Do you have the engine logbook? Can you post some photos of your engine here? 

  • Re: Age and info

    by » one month ago

    Thanks for the info. At least I know now when it was build. It’s in an Ultralight I just bought at a good price. Want to put a electric starter on it and not sure if the kit that Aircraft Spruce sells will adapt to this engine. The serial number that i gave you is 356-1689. I’ve ask Aircraft Spruce about it fitting but they haven’t really replied with correct answer. I think theyre not sure. I know this engine came with a recoil starter, just wonder if it ever came with electric or would the new ones AS sells fit. They’re numbers are not 15-05370. Says its supposed to fifty all the small rotax’s. The reason I sent you original e-mail was to find out the year so I can track down a starter. As far as a manual the ones online will do. I’m familiar with this engines from having Skidoo’s long ago. I’ll try and send some engine pics here also. It is a 503, single carb. 

    26330_2_FB30475C-5649-4C6A-8F53-588594EA4A22.jpeg (You do not have access to download this file.)
    26330_2_EF8C6EFC-17A8-4E78-9176-69171F5162C1.jpeg (You do not have access to download this file.)
    26330_2_EA6A3F4D-771C-48C2-9F63-61F33F28DFAE.jpeg (You do not have access to download this file.)

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