Hello all,
I am back into my '78 Special restoration after a couple of months' absence. Removed the oil filters and found the telltale signs of black plastic and shiny aluminium - not a lot but enough to give that "Oh no!" feeling. Have read all the threads on this topic and the general consensus seems to be to remove the motor, replace the front guide and chain, check the bores, replace the rings, lap the valves and clean up the pistons and head. The problem I have is that I have never had the motor running for more than a few minutes before I began the strip down process and, even then I wouldn't have recognised the metallic sound of a deteriorating cam guide. The PO had replaced the bushings and the steering bearings, so his maintenance schedule wasn't too shoddy. It is possible that he has replaced the guide and I am seeing the detritus the motor can retain for a period of time after the replacement.
I could change the oil and run the motor for a while to see if the deposit of break down sediment continues but she is stripped down and ready to pull out now. The motor's compression is good but the plugs in situ are black with carbon which makes me suspect that the head may be in the same condition. She has 21,000 miles on the clock which would appear to be the mileage that most contributors cite as time for a few replacements. The bike is an American import in surprisingly good condition so I have no way of checking with the PO.
So, do I pull the motor on the off chance that there may be things inside that need attention, or do I put it back together, complete my rebuild, start it up and run it for a few oil changes and then make a decision? What would you do?
I am back into my '78 Special restoration after a couple of months' absence. Removed the oil filters and found the telltale signs of black plastic and shiny aluminium - not a lot but enough to give that "Oh no!" feeling. Have read all the threads on this topic and the general consensus seems to be to remove the motor, replace the front guide and chain, check the bores, replace the rings, lap the valves and clean up the pistons and head. The problem I have is that I have never had the motor running for more than a few minutes before I began the strip down process and, even then I wouldn't have recognised the metallic sound of a deteriorating cam guide. The PO had replaced the bushings and the steering bearings, so his maintenance schedule wasn't too shoddy. It is possible that he has replaced the guide and I am seeing the detritus the motor can retain for a period of time after the replacement.
I could change the oil and run the motor for a while to see if the deposit of break down sediment continues but she is stripped down and ready to pull out now. The motor's compression is good but the plugs in situ are black with carbon which makes me suspect that the head may be in the same condition. She has 21,000 miles on the clock which would appear to be the mileage that most contributors cite as time for a few replacements. The bike is an American import in surprisingly good condition so I have no way of checking with the PO.
So, do I pull the motor on the off chance that there may be things inside that need attention, or do I put it back together, complete my rebuild, start it up and run it for a few oil changes and then make a decision? What would you do?