Decisions had to be made as to the direction the design would take – was the airbox going to:

  • cover both carbs and be one long box,
  • two smaller boxes which had induvidual filters
  • two smaller boxes connected by piping which went to a larger air-filter situated somewhere to get cool air.

I initially decided that two smaller boxes would be easier to fabricate and design and that combining the piping would allow me to get cooler air (always a bonus), be slightly cheaper (only one filter to buy/change) and easier to maintain (less fiddly to attach I think). However, when I started to think about it, having one long box would solve a lot of my problems. Firstly I wouldn’t need to join two pipes as the box would only have one entry and secondly when I needed to get to the carb-mouths it’d just be one box I’d need to remove.

The first thing to do was decide on exactly how much space I have to play with so referring back to the engine picture

there is 35mm between the front carb and the bodywork, 70mm to the rear. Height is restricted by the curve of the bonnet and the side panel and is much more difficult to measure.