tubes_rock said:
Actually, engine oil doesn't break down when it's just sitting. The acids that accumulate are byproducts of combustion, so since the engine isn't running, you won't have to worry about that.
Change the oil in the engine, and leave it full. This way, the oil will keep things inside from rusting, and actually prtect the inside. Also, it will keep seals from drying out too much. Leaving used oil in it would be a bad for it, but leaving fresh oil in it is the best thing you can do.
Everyone is right about draining the fuel, and putting some oil in the cylinders.
As for the valve springs and things, just remove the valve covers, as though you were going to adjust the valve clearance, and make sure that the springs on one cylinder are relaxed, and that the springs on the other cylinder are as close to relaxed as possible. It may be tougher depending on if your engine is a single-pin or a dual. For this, timing is everything!
The metallurgy is very good in those springs, and they are made to withstand nearly infinite cycles of compression and decompression. The only time a well-made spring will deform under load is if it is pushed beyond it's limits, which in the engine, will never happen. But for good measure, just make sure that the springs in both cylinders are not full compressed, and they will be just fine.
If you do wrap the engine up in a plastic bag, be sure it it well sealed with a desiccant (silca gel or whatnot). If you can't get a good seal, or a good desiccant, leave it in the open air. Open air will dissipate any accumulated condensation or moisture, but if it is sealed in a bag, it will just rust the engine.
Block the intake and exhaust ports with good shop towels or clean rags. You want air to be able to flow through them, but you want to keep the dirt and critters out.
--Justin
Great advice and I agree, with one small exception.
I wouldn't wrap the engine up at all... just let is sit. Put a blanket over
it if you wish, but don't wrap it up.
They do make special engine wrap bags that you can wrap one up in,
but I honestly don't know where you can get them.
They are the same type of bags that you can buy for firearms.
They are a breathable plastic and they are designed to keep junk out,
but still breathe.
Virgin engine oil won't have acid problems... as tubes state,
the acids come from combustion by-products mixing with moisture.
So, storing with fresh oil is not a problem and probably something I would do.
I would avoid turning the engine over also.
Remember, crank and cams ride in a suspension of oil, the
do not actually ride on the bearing.
Without oil pressure, when an engine has sat for a while and the bearings
are dry, turning the crank and cam could smear the bearings.
On the top end, I would remove the valve covers and loosen the valves,
if they are not hydraulic. I would also get a non-sheding brush and
coat the valves, springs, etc with a good coating of STP honey.
Don't glob it on, just give it a good top coat.
Fogging the cylinders is also a good idea...at the very least, shoot some
oil down the plug holes.
Put some anti-seize on the plug threads so they don't corrode up in the holes.