This is what I would do if it were my YS that had been sitting for any extended period of time.
I know he ran it dry each time but any fuel left will be old fuel so if it were me I would replace all the tubing including what is inside the tank. However sometimes the tank can be a bear to remove in that case I would rinse the tank using the old lines then replace what I could.
Your fuel should be pure synthetic as the silicon parts in the regulator/pump do not like petroleum based lubricants or castor.
Before you start remove the glo plug it makes things easier to work on.
You have good compression when you roll it over so the valve train is working ok you don’t know how much lube or if the valve clearances are correct. You can assume everything is ok as it ran when it was put away. If you decide to check it you must be careful not to tear or damage the valve cover gasket as some of the YS engines use the space to compress the fuel charge for the intake. You can usually remove the cover without damaging the gasket by just loosening the two cap screws and tapping on the cover until it breaks free of the gasket. Now you can remove the cover and check the valve lash and lube. A bit of 20/20 fuel down the pushrod tubes and on the rockers and valves and that should be good until the natural lube path takes over.
I have my own way of setting the valve lash that others may not agree with so I will just say it’s worth while to make sure you have the valve lash adjusted to the specifications.
With the plug removed squirt a bit of fuel in the cylinder and down the open carb. Spin over by hand never with a starter and the engine should feel smooth as silk. If you leave a little fresh fuel in the tank you should see fuel work its way up the fuel line to the regulator then out the regulator/pump to the carb as you continue to roll the engine over. The regulator/pump are working correctly.
Check the glo plug and make sure it is bright when lit reinstall, fuel up and try starting it.
The bearings are either good or they are not, running the engine will tell you right away no bearing noise your good to go but if you hear noise then replace them before damage to the engine can occur.
Last edited by Propworn; 04-19-2017 at 03:05 PM.