Well my 1989 BMW K100RS is getting closer to being back on the road. Yesterday Spotty and I put in a big day replacing the battery, rebuilding the front brake master cylinder and installing a new fuel pump. Each job was a pain as a PO had done some weird wiring mods and for some reason there’s even a mercury switch of some description dangling from a bracket that’s been fabricated with some crappy electrical connections, that all had to come off to get to the much smaller battery that he’d installed. We installed the huge Motobatt that I’d bought for it. Interestingly the old battery must’ve had a volt or two left because we could just make out the faint digits on the electric clock. We put the old battery on his charger and it appeared to be taking a charge.
I bought the brake master cylinder kit from “Moto bins” in England, and it was a simple job to remove the MC, and once we’d cleaned it (and unblocked the bleed port, which was blocked solid) we reinstalled it, got a good lever pressure and were pretty happy until we realised that there must be a blockage further along the system because the brake lever was not moving at all, so we’ll have to try to flush the system (with all the extra piping for the ABS modules) and if that doesn’t work I’ll delete the ABS completely and run brake lines directly to the calipers. Old BMW rubber brake lines have a tendency to rot from within, and block themselves so it might be time to buy some new hoses for it.
The fuel pump is inside the tank so first we had to syphon the 9 year old fuel out of it. Once we could see the bottom of the tank we realised that the tank is aluminium, so no rust! Yay! Only problem was there were lumps of black gooey crap all over the insides of the tanks. There’s a rubber “anti vibration damper” that the pump sits in, and the old one had turned to horrible sticky black mud that was of the same consistency as black gasket goop, so we had to scrape/scrub it all out then tip in a bottle of brake cleaner to break it up, then a gallon of gas to swish it around followed by a bucket of hot soapy water. What a PITA!
Anyway once it was as clean as we could get it we used his shop vac to suck out any remaining water and installed the new pump and filter. By this stage we’d been working on it for 7 hours and it was getting late, so I didn’t bother driving to the gas station to buy a couple of gallons of fresh gas and fire it up. I’ll grab some fuel tomorrow after work and add some acetone to remove any moisture that might still be inside all the nooks and crannies, and some upper cylinder lubricant as the cylinders will be very dry after sitting since 2015.
Overall I’m really happy that it’s going to be back on the road again soon, I just hope that the brake issue won’t be too painful.
