I recently helped a mate with a early L-series FL1 and changed a few brake pipes. When bleeding the system, I got the impression that the brake fluid had never been changed, very milky and full of cloudy guey patches. I completely bled the system and drew through around 250 ml of fluid on each corner after the air cleared but the brake pedal feels spongy to me (although the owner thinks it's an improvement!).

Hence I want to flush the system out properley - I read in a Haynes manual that you can use methylated spirit for this but just wanted to check if anyone had done this before and what they had used? My concern is that meths might attach the seals etc. ?

Richard

just keep bleeding fluid through till fresh comes out,youll regret doing anything else ,though its quite possible m/c will need replacing

Meths is fine for cleaning hydraulic brake components as it will dilute brake fluid. I would not use it for flushing as it could cause the seals to dry out and cause problems. Don't forget that the bleeding sequence on the FL is the reverse of the norm. You start at the nearest to the master cyl and then work your way through doing the furthest last. If any of the bleed nipples feel excessively slack and wobbly when you undo them it can cause air to be drawn past the threads, if this is the case, remove the nipple and wrap a few turns of PTFE tape (The stuff Plumbers use) around the threads DO NOT put any on the cone seat at the end. This will stop any air being drawn in. You can leave the tape on and tighten the nipple when done as normal. It will help prevent the thread seizing up due to corrosion in future as a bonus.
Don't bother buying the small bottles of brake fluid either..get yourself a 5 litre container from a good motor factor, it works out cheaper and will last for ages. Buy a decent brand e.g. Lockheed, Ferodo, Pagid etc. and standard DOT 4 will be fine. No need to buy the synthetic stuff either the FL braking system is not designed for it.