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| Engine
Rebuild 3: Re-assembly - Bottom End. |
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With
the crank removed, thouroughly clean the inside of the cases. Pack
any openenings with clean cloth to prevent loose sealer from working
its way into the transmission or oil galleries, and clean any residual
sealer from the crankcase mating surfaces. Double check the oil
feed holes to the crank once again.
Always use
new crank seals when replacing the crank. This may sound obvious,
but a new Honda crank is not supplied as a matter-of-course with
fresh seals, so don't be tempted to use the old ones if you neglected
to order them, just to save time! Unlike some 2-stroke engines,
the crank seals CAN NOT be
replaced without splitting the cases.
The next
job is to pre-lubricate the main bearings with 2-stroke engine oil. |
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Pre-fit
the crank to align the seals and bearings. You will notice the seal
on the flywheel side has lugs to help locate it in the cases, and
the clutch side has a lip around its' entire edge, and neither actually
sit flush to the bearings. The bearings have locating pins to help
prevent them spinning in the cases and align correctly. Pre-fitting
the crank will ensure that it can be fitted with minimum time and
fuss once the new sealer has been applied to the cases.
Once
the seals and bearings are aligned, lift the crank back out and
carefully set to one side. Apply a light smear of high temperature
grease to the seal and bearing seats. This will help prevent the
bearings and seals moving as the cases are reassembled, and also
act as a liquid gasket. |
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Use a high quality
liquid gasket (such as Solvol Blue Hylomar or Triple Bond 1104) and
apply a light even coating to both crankcase
halves. Lower the crank into position, checking the alignment of the
seals and bearings as in the picture below. |
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Once the crank
is lowered into position, re-check the alignment of the bearings and
seals. The seal on the clutch side is a little awkward to seat correctly
as it is a tight fit, so make sure its' lip seats correctly in the
groove. If necessary, gently tap the crank webs with a rubber mallet
to seat the seals. Only use just enough
force to seat the seals. |
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Lower
the top crankcase into position, the case will need to be tapped
down to seat it correctly. Before finally tapping the case home,
check the alignment of the primary drive seal. Insert the 5 bolts
into the top case and fasten them "finger tight". Stand
the engine upright (it will sit quite stably on the upper and lower
rear engine mounts) and insert the 5 M8 bolts into the underside
of the casing, again tightening "finger tight". Once all
10 bolts are inserted, it's time to tighten them to the specified
torque. |
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| NOTE: |
Torque
wrenches are precision instuments, and should be handled and used
only as stated in the manufacturers operating instructions. Only a
correctly calibrated torque wrench should be used as incorrect readings
on the gauge can lead to premature failure of components or shearing
of the smaller bolts if overtightened. |
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Always
return a torque wrench to its' neutral setting after use. |
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Starting
with the bolts on the top, tighten them in 2 stages in the order specified
in the diagram below. The M6 bolts should be tightened to 0.8kg-m
first, and then 1.4kg-m, the M8 bolt tightened to 1.5kg-m and then
2.5kg-m. |
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On
the underside, tighten the bolts up in the specified order, again
in 2 stages. As each bolt is tightened, turn the crank through approximately
45 degrees, torque them first to 1.5kg-m, and then hit them with a
plastic mallet as this helps to settle the cases. Finally, torque
the bolts down to 2.1 - 2.5kg-m. |
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With
the crankcase bolts tightened, reassebly of the various components
is simply the reverse procedure to the strip-down. Each component
being reused should be checked for excessive signs of wear. Close
inspection of the components will also usually act as a guide to their
orientation upon reassembly. Starting with the clutch, refit the inner
collar (part# 15 - wet clutch, part# 17 - dry clutch, see below) if
removed, and then the 2 needle-roller bearings to the input shaft. |
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Apply
a little grease to the seats of the drive gear o-rings to hold them
in place, and fit the locating dowel-pins, then refit the drive gear.
Use a little thread-lock to the 3 Allen screws securing the drive
gear and tighten them to a torque of 8Nm. Tap the primary drive gear
into its' position on the end of the crank, noting the white balance
alignment marks, and tighten the securing bolt to 9.0 - 10kg-m. Insert
the pushrod into the input shaft. |
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Note
the alignment mark on the secondry gear on the clutch basket. Turn
the crank until the white dots will line up with the basket (or gear
in the case of the dry clutch models), once it is slotted into position.
Remember the thrust washer behind the hub, and then slot the hub into
position. Refit the outer thrust washer and centre-nut. Lock
the crank as shown in the previous section with the clutch holding
tool, and tighten the centre-nut to 5.5 - 6.5kg-m. |
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The
clutch plates can now be installed. Refer to the diagrams below
to check the order the various plates (and other components) should
be fitted. |
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| Wet
Clutch models: |
Fit
the flat judder spring (part# 14) first, and the shaped spring
(part# 11) with its' OUTER edge raised away
from the engine, so it appears 'concave' as you look at the
assembly. |
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| Dry
Clutch models: |
We
advise the fitment of new damper rubbers (part# 8) to the inner-most
friction plate because as these wear the clutch can become rather
harsh. |
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| Top
Tuning Tip: |
Dry
clutch models can benefit from a simple upgrade by replacing
the 2.0mm steel plate (part# 10) closest to the engine with
a 2.9mm plate (part# 9) as utilised thoughout the rest of the
assembly. This adds a little extra pre-load to the clutch springs,
and is an effective way to increase the clutch's resistance
to slipping. |
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With
the plates installed, replace the ball-bearing and pressure plate
spacer and then fit the pressure plate. Torque the 5 plate retaining
screws to 5Nm. |
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| NOTE: |
Take
extra care not to over-tighten the 5 pressure plate screws as the
hub can be easily damaged. |
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Apply
a thin smear of instant gasket to the engine case in preparation for
refitting of the gasket and clutch cover. Do not overlook the waterpump
drive shim/washer, which can be temporarily held in place on the engine
casing with a small dab of grease. Now fit the new gasket. Dowels
help align it, and the instant gasket will hold it in place around
bolt-holes. |
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Apply
grease to the kickstart shaft seal to ease fitting, and carefully
refit the clutch cover. |
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| Torque
the cover retaining screws to 1.0 - 1.4kg-m. |
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