Topic: CB550 - Hole in transmission

[drjeffreys]

Hey guys. Recently did a top end rebuild on my '78 cb550. I ported, lapped valves, re ringed, honed, fresh gaskets all around.
It went back together very nicely. I just finished first tank of break in and it is running great, no leaks, carb tune is on point!

Upon addressing a charging issue (turned out to be stator windings grounding out on the case), i noticed some oil and a hole in my case. It looks to be just above the main gear shaft, and i think its the pin that hold the shaft to the bearings or something. The bike makes no strange noise while riding.

Ive attached a picture and a diagram of what i think the pin is, also a link to the fsm section on the "trochoid pump" oiling system which i believe it may be apart of. It appears to enable an oil passage to the bearings on the end of the shaft. I am hoping someone can explain to me its function, and what my options are. I would rather not split the case.

#16 "shift fork pin"


http://manuals.sohc4.net/CB500/HSM500550_6.pdf



Thanks

[drjeffreys]

After some more research, ive realized the pin is there to locate/stop the bearing race from spinning. The pin being forced out of the case means the race is spinning.


PICS ARE NOT MINE, found online. You can see the pin & divot in the race for it.





Thoughts? case can be split from the bottom and hopefully be put back together with fresh bearings?

[mickwinf]

If the pin is not located in the hole in the crankcase when the two halves are bolted together it can damage the crankcase, looks like it has been pushed through the alloy causing the leak. Dave will be the man to tell you for sure.

[drjeffreys]

ahh yes i see what you mean. That is a possibility, ive only had the bike for a year and a bit. I havent split the case, but maybe i never noticed this before and previous owner did it while reassambling.

Best case scenario, im hoping the case itself is holding the bearing race solid in the case. That would be really cool.

The notch in the bearing race, i was hoping it "keyed" into the case where the race sits, so even if the pin came out, the race would not spin in the case. I think i found that to be untrue though . Case being far out of tolerance for the bearing race is now a good possibility.