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GENERAL INFORMATION
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cause the gauge needle to move slightly. If the crankshaft is
360°off, these indicators will not be present.
NOTE
The decompress or mechanism will click loudly once
during each crankshaft revolution. This is normal.
7. Use hex socket on the primary drive gear mounting bolt and turn the crankshaft clockwise and align
the TDC mark on the flywheel with the index mark on the left crankcase cover Remove the hex socket
from the primary drive gear.
8. Perform the following to lock the transmission so the engine remains at TDC on its compression
stroke when performing the leak down test:
WARNING
Do not attempt to lock the engine by trying to use a
tool to hold the Allen bolt on the end of the crankshaft.
Once the combustion chamber becomes pressurized,
any crankshaft movement can throw the tool away
from the engine under considerable force, attempting
to hole the tool can cause serious injury. Engine
damage may also occur to the crankshaft or right
crankcase cover. Lock the engine as described in this
procedure.
a.
Turn the drive sprocket by hand and shift the transmission into top gear with the shift pedal.
b.
Mount a holding tool or equivalent onto the drive sprocket. Use a wooden block and clamp to
hold the holding tool so it cannot move when the combustion chamber becomes pressurized.
c.
Check that the TDC marks are still aligned as described in Step7,
If not, turn the crankshaft as required, then relock the holding tool in position.
9. Remove the radiator cap and the oil filler cap.
10. Perform a cylinder leak down test by applying air pressure to the combustion chamber. Follow the
manufacturer’s instructions while reading the percent of leakage on the gauge. Listen for air
leaking while noting the following:
NOTE
Because of play in the transmission gears, it is unlikely the
engine will stay at TDC on the first try If the crankshaft
turns, reposition the countershaft slightly and then relock it
in position with the holding tool. After several attempts, you
will get a feel of the transmission play and know what
direction the countershaft should be turned and locked.
NOTE
If a large amount of air escapes from the exhaust pipe or
through the throttle, the air is leaking through on open
valve, Check the index mark to make sure the engine is at
TDC on the compression stroke, If the engine is remaining
