Main Shaft
Disassembly
1. Remove circlip (1) from main shaft (2) as shown in the figure.
2. Pull out 5th gear (1), needle bush (2), needle bearing (3), main shaft bearing (4) and low gear (5) with bearing puller (6) and press (7).
3. Remove synchronizer ring and ball (1).
4. Pull out low speed sleeve/hub assembly (1), needle bearing and 2nd gear (2) from main shaft.
5. Pull off synchronizer springs/keys and low speed sleeve from hub.
6. Remove circlip from front part of main shaft and pull out 3rd gear (1), needle bearing, synchronizer ring and high speed sleeve/hub assembly (2).
Inspection
^ Check clearance "a" between synchronizer ring and gear, key slot width "b" in synchronizer ring and each chamfered tooth of gear and synchronizer ring and replace with new one, if necessary. Also, check gear tooth.
Clearance "a" between synchronizer ring and gear (main shaft)
Standard: 1.0 - 2.0 mm (0.039 - 0.079 inch)
Limit: 0.8 mm (0.031 inch)
Key slot width "b" (main shaft)
1st, 2nd:
Standard: 12.2 - 12.4 mm (0.480 - 0.488 inch)
Limit: 12.65 mm (0.498 inch)
3rd:
Standard: 10.0 - 10.2 mm (0.394 - 0.402 inch)
Limit: 10.45 mm (0.411 inch)
^ Check clearance between fork and sleeve.
If clearance exceeds limit, replace fork and sleeve.
Clearance between fork and sleeve
Standard: 0.15 - 0.35 mm (0.006 - 0.014 inch)
Limit: 1.0 mm (0.039 inch)
^ Check diameter of main shaft (1)/needle bush (2) and thickness of main shaft (1)/needle bush (2) flanges as shown in figure. If measured value is out of specification, replace them (or it).
Main shaft/needle bush specification (diameter and thickness)
^ Using "V" blocks (1) and dial gauge (2), check runout. If runout exceeds limit below, replace main shaft (3).
Main shaft runout
Limit: 0.06 mm (0.0024 inch)
^ Using cylinder gauge (1), check inside diameter of each gear. If its inside diameter exceeds specification, replace it.
Inside diameter of gear
1st, 2nd and 3rd
Standard: 44.015 - 44.040 mm (1.7329 - 1.7339 inch)
^ Check chamfered part of each sleeve for damage and excessive wear, and replace as necessary.
^ Check each synchronizer key and synchronizer spring and replace as necessary.
^ Check splined portions and replace parts if excessive wear is found.
^ Check 2nd gear (1) thrust clearance by using thickness gauge (2). If clearance is out of specification, repress-fit or replace defective part.
2nd gear thrust clearance
Standard: 0.10 - 0.25 mm (0.004 - 0.010 inch)
^ Check low gear (1) thrust clearance by using thickness gauge (2). If clearance is out of specification, repress-fit or replace mainshaft bearing and 5th gear.
Low gear thrust clearance
Standard: 0.10 - 0.25 mm (0.004 - 0.010 inch)
Reassembly
NOTE:
^ Before installation, wash each part and apply specified gear oil to sliding faces of bearing and gear
^ Use new circlips on shaft for installation. Don't reuse circlips.
1. Assemble high speed synchronizer hub (3), sleeve (4), springs (1) and keys (2) according to the following procedure.
a. Slide hub (3) in sleeve (4) so that wider flange side of sleeve (4) and boss side of hub (3) face opposite as shown in figure, also aligning hub slots with key location teeth of sleeve (4).
b. Insert keys (2) in hub slots with depression side of keys face center of hub (3).
c. Install springs (1) to internal circle of key locations with spring end gaps apart at angles about 120 degrees each other, in order to apply spring tension equally to each key.
NOTE: Do not mix high and low speed synchronizer keys as dimensions are different.
1. Install synchronizer ring (1) by matching its key slots to keys as shown in the figure.
2. Insert 3rd gear (2), needle bearing (3) and high speed sleeve/hub assembly (4) with synchronizer ring to main shaft (1).
3. Press-fit high speed sleeve/hub assembly (1) with special tool and press (2).
Special tool
(A): 09940-53111
4. Select Circlip (1) that will make thrust clearance of clutch hub 0.1 mm (0.0039 inch) or less and install it.
Circlip thickness specification
Special tool
(B): 09900-06107
5. After installing circlip, check that 3rd gear turns lightly.
6. Check 3rd gear (2) thrust clearance by using thickness gauge (1). If clearance is out of specification, repress-fit or replace.
3rd gear thrust clearance
0.10 - 0.25 mm (0.004 - 0.010 inch)
7. Assemble low speed synchronizer hub (3), sleeve (4), springs (1) and keys (2) according to the following procedure.
a. Slide hub (3) in sleeve (4) with aligning hub slots with key location teeth of sleeve (4).
b. Insert keys (2) in hub slots with depression side of keys (2) face center of hub (3).
c. Install springs (1) to internal circle of key locations with spring end gaps apart at angles about 120 degrees each other, in order to apply spring tension equally to each key
NOTE: Before installing hub (3), sleeve (4), springs (1) and keys (2) assembly to main shaft, there is no specific installation direction on each component. However, when installing assembly to main shaft, gear side of sleeve (4) should face to forward direction as shown in the figure.
1. Install synchronizer ring (1) by matching its key slots to keys as shown in the figure.
2. Insert 2nd gear (2), needle bearing (3) and low speed sleeve/hub assembly (4) with synchronizer ring to main shaft (1).
3. Press-fit low speed sleeve/hub assembly with special tool and press (1).
Special tool
(A): 09940-53111
4. Check 2nd gear thrust clearance.
5. Apply grease to ball (1) and set it to main shaft (3).
6. Install synchronizer ring (2).
7. Install needle bearing (2), low gear (3) and needle bush (1) to main shaft.
NOTE:
^ Check the cut in needle bush and ball are engaged.
^ After installation, check the synchronizer ring (4) moves in circumferential direction.
8. Press-fit main shaft bearing (1) and 5th gear with special tools and press (2).
NOTE: Bring bearing so that its groove for circlip is in the rear.
Special tool
(C): 09940-51710 or
(C): 09925-18010
9. Select circlip (1) that will make its thrust clearance 0.1 mm (0.0039 inch) or less and install it.
Circlip thickness specification
10. Check low gear clearance.