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Title: Aprilia float level missfire Post by: Augustacab on 13 December, 2023, 05:00:52 PM I am nearing the end of my recommissioning of a 1939 Aprilia Bilux, with a series 1 engine. She drives nicely but when I put the power on for a hill she just misses a few beats, also she doesn't tick over quite as smoothly as I would expect. I have had a spark indicator on and they seems okay, so is she short of fuel, or is she flooding? She has a Zenith 30 VIM carburettor, unfortunately the float had a hole in the top, which I have soldered but I had to fill the dimple in the top, to compensate I flattened the matching dimple on the shut off arm. I am struggling to get the petrol level correct, can anybody tell me what the level in the float chamber should be, at least then I would have a good starting point.
Thanks in advance Title: Re: Aprilia float level missfire Post by: Kari on 14 December, 2023, 09:15:09 AM I wonder if you have the right carburettor. In the "Aprilia Instruzione" of December 1952, for the 1350 cc engine, a Zenith 32 VIM is mentioned.
Karl Title: Re: Aprilia float level missfire Post by: chriswgawne on 14 December, 2023, 10:19:47 AM From your description it sounds a little like lack of fuel when opening the throttle. The sort of thing which was dealt in later years using carburettors with accelerator pumps & jets Have you a manual choke you can apply on acceleration? Or maybe larger jets?
Chris Title: Re: Aprilia float level missfire Post by: davidwheeler on 16 December, 2023, 09:56:19 PM Fulvias have had to fit larger jets to cope with modern petrol's different viscosity...
Title: Re: Aprilia float level missfire Post by: Augustacab on 02 January, 2024, 04:50:53 PM Problem solved, the petrol level should be approximately 3mm below the bottom of the venturi hole where the petrol enters the choke tube. This equates to 16/17mm down from the top of the float bowl.
She runs well now, yesterday we did 75 miles, her first decent run in 45 years!!! Title: Re: Aprilia float level missfire Post by: Kari on 05 January, 2024, 09:48:01 AM Very good to hear that the Bilux is up and running. I recently have found an information sheet which is describing how to check the float level with the aid of a special tool. Listed on this sheet are various carburetors.
Yours would be 18 mm. You seem to be close enough with your setting. regards Karl Title: Re: Aprilia float level missfire Post by: Augustacab on 24 January, 2024, 04:22:53 PM Thank you Kari nice to have it confirmed. Running nicely now.
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