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Comet Primary Chain Case Leak

Pharquarx

Well Known and Active Forum Website User
Non-VOC Member
I have had my Comet out for several rides now in the nice Southern California weather. It runs like a beast now that the carburetor adjustment mysteries are in the rear view mirror. One thing that still bothers me and that is the leakage from the primary chain case where the Burman gear box shaft penetrates. I installed the Conways modified clutch and it is operating nicely, no issues there. I am under the impression that there is no seal at this point. When I installed the clutch assembly, I fashioned and installed a leather seal between the case and the washer/clutch bearing, but it has not proven successful. I will probably pull this assembly back apart over the next few months and am looking for suggestions as to how to cure this leak, which, after riding the Comet, consists of a significant drip and, of course, the fouled undercarriage.
 

craig

Well Known and Active Forum Website User
VOC Member
Me too!, 60 years later....any suggestions?
 

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clevtrev

Well Known and Active Forum Website User
VOC Member
I have had my Comet out for several rides now in the nice Southern California weather. It runs like a beast now that the carburetor adjustment mysteries are in the rear view mirror. One thing that still bothers me and that is the leakage from the primary chain case where the Burman gear box shaft penetrates. I installed the Conways modified clutch and it is operating nicely, no issues there. I am under the impression that there is no seal at this point. When I installed the clutch assembly, I fashioned and installed a leather seal between the case and the washer/clutch bearing, but it has not proven successful. I will probably pull this assembly back apart over the next few months and am looking for suggestions as to how to cure this leak, which, after riding the Comet, consists of a significant drip and, of course, the fouled undercarriage.

It`s caused by your mainshaft bearing pressure leakage, and possibly overfilling of the primary. Fit an oil seal on the mainshaft.
 

Pharquarx

Well Known and Active Forum Website User
Non-VOC Member
It`s caused by your mainshaft bearing pressure leakage, and possibly overfilling of the primary. Fit an oil seal on the mainshaft.

That is, the mainshaft of the Burman gear box that faces the backside of the primary chain cover?
 

Hugo Myatt

Well Known and Active Forum Website User
VOC Member
Are you sure it is a chaincase leak? Both the chain oiler and the engine breather chuck oil about in this area. Now there is a cunning recess forward of the gearbox sprocket between the inner chaincase casting and the drive side engine casting which is suitably placed to pick up any oil that happens to be flung forward. This can occur despite the cast in deflector forward of the sprocket on the back of the inner chaincase casting (Always supposing this is still there. Unfortunately this is frequently broken away due to a rear chain breakage at some time and the chain being wound up on the gearbox sprocket.). When stationary this recess will stealthily discharge its collected oil onto the ground giving every appearance of an oil leak. If you extend a digit below the chaincase and behind the inner casting and feel forward you will find this hidden recess and probably be rewarded with an oily finger.
 

Pharquarx

Well Known and Active Forum Website User
Non-VOC Member
Got it !!!! Now it becomes clear what the potential problem is, would have never looked in that direction !!!
Thanks much.

I looked a little further in Stevens and Richardson for some details on this and found the attached below. I am posting it for my fellow Cometeers, I assume that I am not the only one with this issue. I will order parts tomorrow and keep you posted with my progress.
 

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craig

Well Known and Active Forum Website User
VOC Member
500cc

who has these crankshaft sealing pieces available?
 

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Pharquarx

Well Known and Active Forum Website User
Non-VOC Member
who has these crankshaft sealing pieces available?

I just ordered everything from the VOC Spares Company. Parts Numbers E229, E216/1 and G24. I assume that the three countersunk screws behind the engine sprocket can be reused. The only setscrew that I could find in the Parts Data Base meeting the requirements in Richardson is part number 845. If the existing cannot be reused or have a different function then I will determine what I need and I will order those separately as well as a tap to complete the installation.
 
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