QuestionI just acquired a 1981 Yamaha 550 Maxim for my mother. The problem is it has not been started for about 12 years. The reason it sat for so long is it needs a top end rebuild, how do you exactly do one and what parts would i need? What else do you think it might need done to it; just off the top of your head?
Thank you for any of your help
Jason
AnswerJason, you need to acquire a shop manual, good set of metric tools and a high limit credit card.
I am not a Yamaha guy, but I believe that they are DOHC engines; two cams, 8 valves and 4 carburetors.
http://www.bikebandit.com/houseofmotorcycles/yamaha-motorcycle-xj550h-1981/o/m81...
If you are lucky enough to get it apart without breaking any fasteners or parts, the sequence is removal of the fuel tank, air box, carburetors, exhaust system to start. Hopefully, you can work on the top end in the chassis. Otherwise, you will have to pull the motor out of the frame for rework.
Top cylinder head cover comes off, then the camchain tensioner, so the camchain can be loose enough to allow the camsprockets to be removed from the cams and then slipped out and away.
All the valves have adjustment shims on top of each valve assembly and those clearances will have to be measured before disassembly and then after reassembly. Doing a valve job will change the clearances of the valve train, so you will have to acquire a new set of shims to get valve clearances back to where they belong.
The cylinder block will need to be removed from the pistons, measured and then rebored to a size that will allow proper piston fit. You will be buying new pistons, rings, gaskets, seals, valve stem seals, O-rings and other small parts. If the engine has a lot of miles on it, the camchain needs to be replaced. The chain is endless, so you will have to tear down the whole motor to remove the crankshaft and loop another chain over the middle of it.
I can imagine that you will drop at least $1,000 into the motor work, then you have to rebuild the carbs and fuel system. Old bikes have old tires and chains, so those will need replacing. Then the new battery, fork seals, air filter, oil filter, exhaust gaskets and who knows what else.... Now you are up to about $2k...... The bike is worth about $500-800 running. Check out the www.nada.com site for current values, all of which depend on the overall condition of the bike and the miles on engine/chassis.
This can only be a labor of love, not profit and probably not a viable way to put your mom up on 2 wheels. Shop around for something newer, with low miles and all ready to ride.
Good luck, in any case.
Bill "MrHonda" Silver
