I recently got a 1990 KX500, and after riding the bike just enough to fall in love with it, I'm finding out that the previous owner was not all that honest about it's condition.
Things I've found so far:
- Water in transmission, milky oil: I found that the water pump seal was bad, and in fact, had silicone over a crack in it... Minimal shaft play, unable to feel any groove in the shaft with a screwdriver or a fingernail, so I just replaced the seal. Milkiness returned once, but it'll probably take another change or two before I know if it's gone for sure.
- Frame crack at the top near motor mount: Ground/notched, MIG welded and painted over. Seems to be holding fine.
- Stripped out drain plug: It came with a cut off 1/2-13 bolt in it, which then stripped. I made a guide jig and put a Perma-Coil in it to bring it back to 1/2-20. Then I installed a Fumoto F101 drain valve with about 1mm of metal "wall" left. It seems like it'll hold, though I don't exactly want to torque it too hard. The valve is well constructed and protected by my skid plate, so it should be safe. Should make changing oil easy, anyways.
So ok, it looks like I got it under control. I come home today and check the bike over in preparation for some badly needed riding time tomorrow and discover:
- Oil leaking from output shaft/chain sprocket: Must be a seal, unsure if installed from the outside or inside.
- Whirring noise at idle: Sounds suspiciously like the kind of noise a roller bearing makes when it's worn out. I pull the stator cover off and push/pull on the crank and notice that it wiggles up and down and side to side very, very slightly, though you can feel it and hear it tick when it moves. Also, the crank has some end play as well, when pushed or pulled directly. I turn the flywheel with my hand and notice that there's a very slight slack before the piston/rod move as well... Looks like I need a full rebuild. d**n it!
So, it looks like I won't be making it to Pismo after all. Further more it looks like I'll be sitting out on riding season trying to get this thing put back together. Does anybody have any ballpark estimates on how much I'm looking at to go through the entire engine, bottom end and top end rebuild, with crank, rod and new piston? Even though I got the bike for cheap and have become completely addicted to it, I could use some encouragement... I'd appreciate any information!