There is way more to do right than removing the tires and slipping them into a bag.. Here is what you should do to assure the engine alone is stored correctly (Plus a few other tips)
Engine Storage – Gregg Pelton (The Gimpster)
I like to have the engine runnable to completely set it up for
storage. Where I will add 'Sea Foam' to the fuel system and let it
run for 10-20 minutes so the carberators will get a good dose of it
inside to cover the main corodable componens. Preferably, near the
end of the run time, a fogging spray ( available at a motorcycle
shop ) should be sprayed evenly into the carb throats to totally
coat the valves, pistons and cylinder walls. The fogging oil will
not run down the engine components and settle at the lowest part,
like engine oils will after longer setting times, it will stick to
the components. And will stay coated where the engine is stopped.
When the engine is stopped, drain the carbs, drain the engine oil
and refill the crankcase with fresh oil. ( even if oil is not due to
be changed, combustion byproducts produce acids in the oil that can
corrode engine components ) Turn the engine over a few times with
the starter to get frash oil into the oil pump ( ignition off ) And
the clutch depressed to get fresh oil in the discs before releasing
it. Bleed the clutch system of all old fluid and replenish with new
DOT 4 brake fluid from a sealed container to be sure once the engine
is removed that old brake fluid that may have moisture in it cannot
corrode the clutch slave cylinder, and when the engine is removed,
fill the line all the way with brake fluid and cap it off to prevent
the moisture/corrosion thing from taking place while stored. Cap off
the crankcase oil breather outlet. Duct tape the exhaust ports if
bolt on exhaust plugs are not available. If the carbs were removed,
plug off the intake manifold boots, and if they were left on the
engine, cap carb throat the opening with plastic bags and hose
clamps, cap the fuel inlet, and carb breather hoses. Any extra
wiring harnesses, and coils that can be removed should be so they
will not get damaged if the engine were to be tipped while
transported, moved around the shop etc... The pulser wires if left
on the engine should be neatly tucked away so they do not get
damaged. Cap any oil line fittings. Coat the clean engine with WD-
40, Cosmoline or equivalant ( what ever you use, make sure it will
not harm rubber and plastic components ) and wrap the engine in a
lightly oiled plastic ( on the engine side of it ), and secure it as
well as possable. Another alternative is to use shrink wrap like
used to cover boats when they are shipped or stored in the off
season. Of coarse it can be obtained from most boat shops. If the
engine was stored with the header in place, I would sugest steel
wool in the exhaist exit before sealling, to keep mice out in case
they get past the exhaust sealing material. Mount or band the engine
to a suitable wooden base, or engine stand to keep it stable.
Did I forget anything ? Oh yeah, if the engine was not running
before storage, and cannot be fogged, clean around the spark plugs,
remove the spark plugs and put a tablespoon of oil in each cylinder,
and turn the engine over ( with a wrrench ) a number of times to
coat the pistons, cylinders, etc... and reinstall the spark plugs.
Then remember to undo everything you just did to get it running
again when reinstalled into a chassis. Change the oil also before
starting, as moisture condensation may have contaminated it while
stored.
Hope this helps ...