I've just made my throttle pedal much lighter, thanks to advice from somebody on here whose identity I cannot recall. I replaced my standard 'bicycle-brake-cable' type outer, with a Teflon-lined, steel-braided, outer cable. I also shortened it, to eliminate an unnecessary 'S' bend which just didn't need to be there. An amazing improvement, so easy to do. De-grease your inner cable, then replace the outer with the following components:

https://www.ebay.co.uk/itm/162226131285 This is the outer cable material. (I bought 2 metres)

Venhill Engineering Ltd: SKU: FT4SN or SKU: FT4LN These are the ferrules which I chose.

All of this took only 20 minutes or so to install. I was also able to install a weaker return spring on the carb, due to the reduced drag in the cable run.

Total cost: Approx £13.

You won't find the ferrules on eBay - go straight to Venhill.

This was such a great and easy upgrade. Enjoy!