Top gear disengages. This is most likely to occur on early type gear
boxes before 7988 (250 c.c.) and 2300 (350 c.c).
To rectify, discard the sleeve gear 041273 and sliding gear 041276 as
shown in Fig. 3. Replace the sleeve gear with modified type 044075, also
sliding gear 044076, which use undercut dogs for positive engagement.
Should the fault develop on a later type gear box, the plunger 042835 may
be damaged on the extreme end, or the spring for plunger 040045 is weak
allowing the gear to disengage. Both gears must be changed to convert.
Third gear only disengages. The only remedy is to renew the two third
gear pinions 041276 and 041277. Usually this is due to bad gear changing
and possibly clutch drag.
Bottom gear only disengages. This can only be due to end play between
the first gear pinion and kickstarter bush. To remedy, use a shim washer
.020" thick placed over the layshaft between the pinion and kickstarter
bush.
Difficulty in selecting the gears. Usually due to a distorted pawl spring
041327 preventing the pawl from rocking.
Gear pedal does not centralise. The footchange pedal spring is broken.
Replace with improved cross over type 043453. Separate the legs when
fitting.
FIG 13 Lightweight gearbox with end cover removed
POSSIBLE FAULTS
It will be seen in Fig. 13 that the gear box internals are situated above
the centre line of the gear box shell. It is for this reason that at least three
pints of engine oil must be filled and maintained for satisfactory lubrica-
tion.
THE GEAR BOX
250 c.c. and 350 c.c. Lightweight Models
54
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