'87 K75S Removing lower crankcase

[132524]

1987 K75 s For years I’ve always wished I could stop an oil weep coming from the TOP of the lower crankcase half just under the engine block and on both sides. I decided then to put up with it. Several weeks ago I needed to replace the darn clutch O-ring and track down a vacuum leak around the T.B’s. One thing led to another and the frame is removed from the motor. The motor is now sitting on the work bench with the T.B’s off along with the bell housing and yes, the water pump needed to come off as well as the rear main seal to address taking the lower crankcase off to reseal. Clymers makes like that after you turn the motor upside down, take all the bolts out, carefully lift up the lower crankcase so the output shaft stays put, put in two new O-rings then reseal. Other information I’ve read is that the output shaft is under tension and stuff could go flying. Any thoughts? and yes another sealant question, what kind do I use there. Mike #132524

 

[mohler]

The shaft isn't under tension, but there is a retaining ring ,next to the front ( smaller) bearing that sits in a groove. When lifting the lower casing the ring and bearing may get moved a little out of position, just have to check that they are in the right place when putting back together. Also the output shaft and crankshaft gears have alignment marks where they mesh,
to keep the shafts in balance. I was into mine to replace the large bearing that was bad and found these alignment marks were 6 teeth away from being correct. Not sure if that was the reason for the bearing failure.

 

[132524]

I got the lower crankcase off just as suggested. I want to make sure I’m looking at the right marks on the output shaft gear & crankshaft. There are two marks on the inside of the output shaft gear. One is a little round indentation right next to the teeth & the other sort of in the middle of the gear which is a round bump & is larger. On the crankshaft on the inside, a small line, which mine has a tiny bit of orange paint. Interesting those marks on the output gear are six teeth apart. A couple of other things I need to ask about are the spring that fell off the starter countershaft when I pulled back the intermediate flange (bell housing). And lastly, (so far) a shim that I think fell off the bell housing frame location but Clymer’s only pictures one on the left front of the motor/frame location

 

[mohler]

The dimple near the teeth on the output gear should line up with the mark near the teeth on the crankshaft gear, if I remember right it is a line not a dimple.Probably the orange paint mark on yours. What I meant about being 6 teeth apart was that someone previous to me didn't line it up properly.

 

[mohler]

As for the starter countershaft spring, look at a parts fiche diagram for proper orentation. My bike aslo had a fiber washer shim between the intermediate housing mount flange and the frame .

 

[132524]

With the motor upside down, I'm installing the lower crankcase on the block but it will not bottom out. I notice that the grooved ball bearing not seating all the way in. I removed the output shaft and just put the gear wheel in and still the ball bearing does not seat. The only thing that stands out for me is that the gear wheel & idler gear teeth are offset from each other just a bit. Suggestions? Mike

 

[mohler]

I think that the idler gear is offset from the output gear because it is spring loaded to prevent backlash between the two gears. When the shaft and bearing are pushed down enough for the idler gear to rotate to the same position as the output gear, the bearing should be seated. I've seen photos in a repair manual of the bearing being tapped down using a wood block before the case is installed.

 

[132524]

1987 K75 lower crankcase update. Well I got the lower crankcase on. I did what Clymer’s said not to. I installed the lower crankcase, installed the four “inner” bolts finger tight and then with a ratchet on the two hex bolts came down what turned out to be a half turn and bingo, the bearing was set. I turned the crankshaft several revolutions and there wasn’t any binding or scraping.
Several things that stood out for me by doing this job was that I found what may have been causing frequent replacement of the clutch O ring, was that the output shaft had a burr just on the other side (back) of the threads, probably where I had struggled to get a prior O ring out. Another was that the O ring for the coolant between the block and the lower crankcase was a mess. You could see that coolant had migrated beyond the disintegrated O ring almost into the oil. This is the same part # O ring used in the water pump. And lastly, the amount of old sealant found in the oil strainer & bottom of oil pan. It was alarming. I’ve had the oil pan off before but had since resealed valve, crank and timing covers. So looking back, two of the issues are my fault ( burr & sealant) the other probably the miles on the motor. I would suggest that if your sealant challenged as I seem to be, that you drop your oil pan from time to time to make sure the oil passage ways are clear. The oil/water pump is on using ultra gray and once the intermediate flange (bell housing) is on I’m back into my comfort zone. I’m conflicted still with the spring (P# 11-26-1-460-956) on the countershaft. Looking at the back of the bell housing with countershaft attached, I know of the two “ears” on the spring, the narrow one should be at 12 noon. But is the inside diameter of the spring protruding out at me or in? Thanks to everyone for their help. I would not have had the courage to do this without the support of this forum. Mike