Shop Supplies - Yamaha MM700A Manual

6
be installed in either direction, since both faces have sharp
edges. Stamped snap rings (Figure 9) have a sharp edge
and a round edge. When installing a stamped snap ring in
a thrust application, install the sharp edge facing away
from the part producing the thrust.
Observe the following when installing snap rings:
1. Remove and install snap rings with snap ring pliers.
See Snap Ring Pliers in this chapter.
2. In some applications, it may be necessary to replace
snap rings after removing them.
3. Compress or expand snap rings only enough to install
them. If overly expanded, they lose their retaining ability.
4. After installing a snap ring, make sure it seats com-
pletely.
5. Wear eye protection when removing and installing
snap rings.
E-rings are used when it is not practical to use a snap
ring. Remove E-rings with a flat blade screwdriver by
prying between the shaft and E-ring. To install an E-ring,
center it over the shaft groove and push or tap it into place.

SHOP SUPPLIES

Lubricants and Fluids
Periodic lubrication helps ensure a long service life for
any type of equipment. Using the correct type of lubricant
is as important as performing the lubrication service, al-
though in an emergency the wrong type is better than
none. The following section describes the types of lubri-
cants most often required. Make sure to follow the manu-
facturer's recommendations for lubricant types.
Two-stroke engine oil
Lubrication for a 2-stroke engine is provided either by
oil mixed with the incoming fuel-air mixture or by oil in-
jected into the fuel-air mixture. The models included in
this manual are equipped with an oil injection system.
Some of the oil settles out in the crankcase, lubricating the
crankshaft and lower end of the connecting rods. The rest
of the oil enters the combustion chamber to lubricate the
piston rings and cylinder walls. This oil is burned during
the combustion process, then expelled with the engine's
exhaust.
Engine oil must have several special qualities to work
well in a 2-stroke snowmobile engine. The oil must func-
tion properly in the high operating temperature associated
with 2-stroke engines, as well as flow freely in cold tem-
peratures. The oil must lubricate the engine sufficiently
and bum completely during combustion. The oil should
Internal snap ring
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not leave behind excessive deposits. Refer to Engine Lu-
brication in Chapter Three.
NOTE
The injection oil used by Yamaha snowmo-
bile engines
must
temperatures of -40º C (-40º F). See Chap-
ter Three under Lubrication for additional
information.
Four-stroke engine oil
CA UTION
Four-stroke oils are only discussed to pro-
a
vide comparison. The engines used in
these models o f Yamaha snowmobiles are
2-stroke engines. Only use 2-stroke oil.
Four-stroke (cycle) oil for ATV, motorcycle and auto-
motive engines is classified by the American Petroleum
Institute (API) and the Society of Automotive Engineers
(SAE) in several categories. Oil containers display these
ratings on the top or label. The API classification is not an
indication of oil quality.
API oil classification is indicated by letters; oils for gas-
oline engines are identified by an S, such as SF, SG, SH or
SJ. Using the type recommended by the manufacturer is
important, but some earlier classifications of oil may be
difficult to find.
Viscosity is an indication of the oil's thickness or ability
to flow at a specific temperature. The SAE uses numbers
to indicate viscosity; thin oils have low numbers while
thick oils have high numbers. A W after the number indi-
CHAPTER ONE
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also be able to flow at