Your Water Pump Seal (and probably some other parts) is worn out. Here is a list of parts needed to refresh the water pump and related side cover parts.
It would be a good idea to replace the Water Pump Gear (55) as it is plastic, probably embrittled and may break upon disassembly.
The Water Pump Gear Circlip (54) is one time use only. It's good to have a few extras on hand as you have to pull the impeller to remove the side cover to access the seal.
The Water Pump Needle Roller (56) (Holder Pin) if original, is probably rusted out by now. Consider it a one-time use part. If the pin corrodes or breaks the impeller will stop spinning and overheat your motor.
When installing the Water Pump Seal (60) Note the orientation. Do not bash it in with a hammer and socket. Press it in.
You will have trouble finding (63). It is a special ball bearing with a seal attached to it.
The O-Ring in the side cover (65) gets flattened over time. Replace it now.
Use the correct O-Ring (26) size only. Close enough won't do.
Lay the bike on its side or put a piece of old carpet under the bike so parts don't ricochet off the floor never to be found again.
Tap the kick start shaft as you slowly remove the side cover so that it does not come out with the side cover.
Press the water pump seal in gently into the side cover or have a professional do it for you. Purchase extra seals. You may go through a few trying to get it right.
Grease the Balancer Shaft (aka Water Pump Shaft} and the Kick Start Shaft liberally with grease before reinstalling the side cover. Work slowly. If you nick the Water Pump Seal lip you will be glad you purchased extras.
The special ball bearing seal is discontinued. You may be able to reuse yours or just leave it alone for now. The Bearing/Seal combo thing (63) is not pressed into the side cover very tightly and can be removed, cleaned (seal side) and reinstalled.
Lightly grease the side cover gasket so that you can reuse it again or if you have to redo the seal because you damaged it during installation.
If someone has already replaced the Water Pump Seal many times you may want to consider purchasing a new side cover as it has all of the bearings and seals already installed. They were still available the last time I checked for about $250.00.
CLUTCH COVER
53. GASKET WATER PUMP COVER 800.35.053.000
54. CIRCLIP DIN0471-10X1 0471 100010
55. WATER PUMP GEAR (Impeller) 800.35.055.000
56. NEEDLEROL.DIN5402 NRA 2,5X19,8 0402 251980
60. SHAFT SEAL RING 10X18X4 BSL 0760 101843
25. GASKET CLUTCH COVER 800.30.001.044
63. BALL BEARING SPEC.B.B.SKF 6201 0625 062013
65. O-RING 17,30X2,40 NBR 70 SH 0770 173024
27. GASKET OUTER CLUTCH COVER 800.30.027.100
BALANCER SHAFT
26. O-RING 10,00X1,30 NBR 70 SH 0770 010013
Check with Taffmeisters for readily available individual parts and parts kits and Joel Asbach for the special Seal/Bearing (63).
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