Hi all. Trapjaw from South Africa here. I just bought a (mostly) mint, low mileage 1986 GSXR 1100 G in standard blue and white trim. Everything on the bike is original and unmodded, engine is super clean with no rust, leaks, drips or anything. Bodywork is all original, absolutely spotless. Real gem. Previous owner had it garaged for a long time, and said it hadn't been ridden in months, but assured me she was running like a peach. When I checked it out we started it up, and it fired up and idled decently, but sounded a little noisier than the bikes I'm used to (more modern water-cooled bikes). I put down a deposit to secure the purchase, then was out of the country for a month, and when I returned last week I went to pick it up.
It started okay and I rode it home, but it seemed like it was running a bit rough - would cut out when I stopped and wouldn't idle. I put this down to a flat battery, as it had been standing unused so long. Checked battery voltage - it was low, as I thought. Charged it, put it back in the bike, she fired up quickly and idled no problem. Multimeter readings seemed okay for the charging system. 15 volts while throttle held at at 3000rpm and when revving higher. That was 2 days ago. Did not ride her again until today. So, took her out this morning to run down to the DMV to sort out the paperwork. Less than a kilometre after leaving my house, suddenly starts feeling rough and the oil light comes on. I pull over and kill the motor. No oil leaks, oil level in sight glass is fine. Start her up, oil is bubbling in sight glass, so oil is moving around the engine, presumably, but oil light is staying on while it is running. Kill the motor. Try start again, but now it's reluctant to start.
I don't want to ride it anyway, so a push back home it is. Take out the battery and check it, and sure enough the battery is low. Alright, so, old shitty battery, that's the issue, right? I went and got a new battery, started her up - fired up and idled and sounds relatively smooth, but now the damn oil light is sticking on.
I'm pretty worried now. Any ideas what might be wrong?