These are excelent bikes. You probably should completyly drain and flush the cooling system then refill with silicate free antifreeze. Dilute the antifreeze 50:50 with distilled water – not tap water because the tap water has minerals and other sediments that could harm the cooling system so it is worth the extra money to go distilled. Change the oil and filter I prefer a WIX filter with Castrol Act-Evo 4 Stroke 50W-30 with a form of Oil Stabilizer. Lucas is a very good choice but there are others out there. I would put new D8EA NGK Spark Plugs with a Plug Gap of 0.028 Grease the U-Joint for the rear differintal and change the Rear differental oil. Change out the fork seals and oil along with the dust wipers. There are also air cut off´s in the carburators that you will probally have to replace along with the fuel cut off neadles in the carburator. If there has been gas sit in the tank or carburator i would take it to a professional because the carburator will have to be soaked to get all the gum off. The tank should also be looked at to make sure there isn´t any rust in the tank because it could cause problems down the road if not fixed now. I would also check the brakes and tires before taking it out on the road.