Maico MC250 - Service Bulletin: Reasons for Gear Slipping

3. Insert the thrust washer in the mainshaft, either by inserting the
clutch body, or use some bushes to pull the mainshaft all the way towards
clutch side and tighten the !Minshaft. nut. With a screwdriver turn the cam
into the neutral position. Shifting forI:. should be inspected through t.he
hole (fig. #2 A, B) for up and down axle play.
4. Turn the cern to the first gear posit.ion and insert. the hooked "ire in hole
E (fig. t(2) and lift up the aecond gear Oay.haft. slider). Check the upper
shift fork axle play through the hole A.
5. l".ave the shiftinB C~r-I into the second gear position and hook the "ire into
the hole A (fig. 112) and the third Bear in the mainshaft should be lifted
(mainshaft slider) upwards. (You miBht not be able to find the play if you
did not pull the main9haft to"ards clutch 9ide.) Check the bottom fork play.
6. The cam is shifted to tlle third gear position and the hool:ed wire should be
inserted into the hole B (fig. n) and pre99 down the layshaft slider and
check the upper for!: play.
7. For fourth gear groove the gear into the fourth Bear position and ingert the
\lire in hole t. (fig. ;IL). The third gear b the main shaft. (Mains:,aft
sliding gear) should be pressed down ,.,hile checking the bottom fork play.
For the radial crankshafts tl:e play should be cI,ecleed, if you changed the cranle,
main bearings and crankcaae:i .. :.Jith the heIr of B feeler gauge insert the feeler
gauge in between tlle crank and ~ngine cases. The cranlecase play should be
0.20""" (.OOC") to 0.36 rrrn (0.11:"). If it i9 rrore than that, shims should be
obtained until clearance i. obtained.
Some of the reason9 for gear slipping:
The hooked rachet shou Id be inspect.ed in \,oth edges (f ig. I!3C). Check the pu11rod
for bend. To avoid the over engagement "eld the hool:ed rechet as shown in
fig. '3 B. to "btain the clearance in the C'IBes. Fig. n A OIl to 112 1ml)(1•• 13").
There la a difference in the gear changing crank (shiftershaft) and the gear
changing pullrod between Radials (~50, 1:00, 1:50, SOl, V, Vl) and the S"uare
Barre19. The gear change return apring must be bent and adjusted so that the
gearchanging cran!: shifts in proper \lay, in accordance with the modification
to the pullrod and the crankcase (fig. J~ area9 A &. C). The proper position
for the crank adju9ted "ith the 9ide cover scre\l hole as shown in fig. 1ft,. S.
Illustration Fig. ill: " depicts the related positions for the 250, 1;00, and 1.50
3. Insert the thrust washer in the mainshaft, either by inserting the
clutch body, or use some bushes to pull the mainshaft all the way towards
clutch side and tighten the !Minshaft. nut. With a screwdriver turn the cam
into the neutral position. Shifting forI:. should be inspected through t.he
hole (fig. #2 A, B) for up and down axle play.
4. Turn the cern to the first gear posit.ion and insert. the hooked "ire in hole
E (fig. t(2) and lift up the aecond gear Oay.haft. slider). Check the upper
shift fork axle play through the hole A.
5. l".ave the shiftinB C~r-I into the second gear position and hook the "ire into
the hole A (fig. 112) and the third Bear in the mainshaft should be lifted
(mainshaft slider) upwards. (You miBht not be able to find the play if you
did not pull the main9haft to"ards clutch 9ide.) Check the bottom fork play.
6. The cam is shifted to tlle third gear position and the hool:ed wire should be
inserted into the hole B (fig. n) and pre99 down the layshaft slider and
check the upper for!: play.
7. For fourth gear groove the gear into the fourth Bear position and ingert the
\lire in hole t. (fig. ;IL). The third gear b the main shaft. (Mains:,aft
sliding gear) should be pressed down ,.,hile checking the bottom fork play.
For the radial crankshafts tl:e play should be cI,ecleed, if you changed the cranle,
main bearings and crankcaae:i .. :.Jith the heIr of B feeler gauge insert the feeler
gauge in between tlle crank and ~ngine cases. The cranlecase play should be
0.20""" (.OOC") to 0.36 rrrn (0.11:"). If it i9 rrore than that, shims should be
obtained until clearance i. obtained.
Some of the reason9 for gear slipping:
The hooked rachet shou Id be inspect.ed in \,oth edges (f ig. I!3C). Check the pu11rod
for bend. To avoid the over engagement "eld the hool:ed rechet as shown in
fig. '3 B. to "btain the clearance in the C'IBes. Fig. n A OIl to 112 1ml)(1•• 13").
There la a difference in the gear changing crank (shiftershaft) and the gear
changing pullrod between Radials (~50, 1:00, 1:50, SOl, V, Vl) and the S"uare
Barre19. The gear change return apring must be bent and adjusted so that the
gearchanging cran!: shifts in proper \lay, in accordance with the modification
to the pullrod and the crankcase (fig. J~ area9 A &. C). The proper position
for the crank adju9ted "ith the 9ide cover scre\l hole as shown in fig. 1ft,. S.
Illustration Fig. ill: " depicts the related positions for the 250, 1;00, and 1.50
Maico 72-74.5 Radial Manaual
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