I had the head off my 96 250 for some maintenance work and reassembled everything however there was a pronounced rattle that sounded like very noisy tappets. I drove it that way for a while but it finally got to me. On disassembly there was no evidence of anything out of order the top end looked all good. I also have developed a leak in the lower gasket and while prepping to get at it, removing the head etc. I found that on last assembly I neglected to tighten up the top engine steady-stay and that is where the rattle was coming from. Also my high beam failed to come on as I had to replace the headlight, the old one was burned out. I removed the lamp and bench tested it and it worked just fine, back to the bike again and checking the circuit and there was no power to the high beam wire, following the wire back up to the switch and opening it up there was evidence of green corrosion right at the terminal contact, this is all very small stuff. I mixed a glass full of soda and water and immersed the switch assembly in the solution, there were small bubbles coming from the switch for a few moments until the corrosion was all dissolved and then walla the headlight came on with full brilliance.