I have been doing some basic maintenance and one of the things I tried to do was make sure the timing was correct. The timing is retarded, but I've rotated the timing plate as far as it will go and it is still retarded. could it be a loose timing chain? I'm really not sure what could be wrong. I would think that I would notice something strange if the chain jumped, but my experience with engines is still fairly small, though with my trusty clymer manual I'm learning more as I go. The bike is a 1975 r60/6 and if it matters, it was on the early end of that production year. (seven hundred something out of 5000) Unfortunately I don't know how many miles are on it, since the odometer doesn't work, but I'd guess it could be anywhere from 20 to 50k. any suggestions or possible causes would be appreciated.