Topic: 1975 Cb750 k chain break - now shifts badly

[scottly]

Part #7 has a reduced diameter at the end that the hole in part #5 fits onto. It can be a bit tricky, as the spring is fighting against you. You have to hold #5 in place on the end of #7, then fit the washer and tighten the nut. Also, if #7 is on backwards, the "shelf" will be facing the wrong way, so #5 won't fit over the end.
There are two dowels: the second one may be stuck in the cover? Notice that the hole on the right side is bigger; that's where the dowel fits into. The dowels are necessary to properly align the cover on the shifter shaft, and if one or both are missing the shaft may bind.
Was there a gasket when you took it apart? If the gasket is missing or too thin, the cover can pinch the shaft, again causing binding.
The notch in the outer disc on the end of the drum is the neutral detent, and the small roller drops into the notch when in neutral. I'm guessing the misalignment is what caused the problem all along, and you may have gotten very lucky.  

[rotortiller]

This should help.

[cado007]

Thanks so much Rotortiller and Scotty,
The dowel was in the case like you said and there was a gasket but it did look thin and it ripped so I have ordered a new one.
I love that hackaweek guy.
So I just carefully put a washer by washer 17 in front that is front of part 1.
I believe it is a 6mm hole washer.
Thanks so much - should I use blue loctite when I verify it works smoothly?
Have a great 4th and THANKS

[scottly]

Do you mean you added a washer between part #1 and the #17 washer that's already there? You shouldn't have to add any parts unless some were missing! And DO NOT follow the hack's torque specs unless you like drilling out broken bolts.

[scottly]

At 8 minutes into the video is when the parts under discussion are assembled.

[cado007]

no I have not done nothing yet and will not do on hacks torque specs
I am just trying to wrap my head around what the fix is exactly and what I should do.
I won't be able to implement it for a couple of days - but again trying to exactly figure out what to do I thought I am suppose to shim out #5 so it will sit correct.
Also another thing I did notice - is the way it is now it would go into neutral and 2 3 4 5 fine and not 1st  yet when I gently pull out with finger so it sits like it is supposed to  it would go into 1st most of the time but then if I kept that tension would not go into 2nd. and when I say would not go into I mean it shifts just goes into sales neutral.
Maybe it does this if cover is off I don't know

[scottly]

I think it's just a simple assembly error, where part 5 isn't fit onto the end of 7. Watch the video, starting at 8 minutes, and note how he has to press 5 onto 7 while fitting the washers and nut.

[cado007]

that is certainly worth checking but I may be misunderstanding I thought I want #5 to be further out away from bike - maybe I am misunderstanding but pushing in #7 seems like it would be going further the wrong direction - I attached a photo - Im am new at this so maybe I am looking at it wrong and will check that 7 is correct    Maybe it being incorrect is making it go in more - so I will check that first . I have been watching that hack video so I am glad you warned me about his torque specs.

[scottly]

If 5 isn't sitting flat on the ledge on the end of 7, it won't line up with the disc at the roller end.

[cado007]

thanks 

[HondaMan]

that is certainly worth checking but I may be misunderstanding I thought I want #5 to be further out away from bike - maybe I am misunderstanding but pushing in #7 seems like it would be going further the wrong direction - I attached a photo - Im am new at this so maybe I am looking at it wrong and will check that 7 is correct    Maybe it being incorrect is making it go in more - so I will check that first . I have been watching that hack video so I am glad you warned me about his torque specs.

Here's some pix of how that arm should look with its little wheel: make sure your "wheel" is riding on the edge of the shift spindle? I have seen more than one where the "wheel" or its "arm" was bent, chipped or broken and it wouldn't ride straight on the shift drum spindle. Then it won't track on the shift spindle's outer rim, falling off at times and preventing the associated gear where it did.

If nothing else: maybe trying loosening the 6mm nut (10mm wrench size) on the end of the shaft that holds the arm, about 1/2 turn or so, and lift the roller of the arm up onto the edge of the shift drum detent like Scottly is pointing out: it should stay there after you retighten the nut.

[rotortiller]

A washer under  the outboard stepped bushing  will push it out, pushing it out will push the lever with the wheel out, pushing the wheel out will cause it to roll on the edge of the thick disk. I suspect the incorrect stepped bushing with a 6mm hole (likely) or another part might be in place. Maybe from the inner part of the mechanism? Take the thing apart and look at it and compare the two stepped bushings.

If you look at the OP pictures it can be seen how the neutral detent arm is sitting low on the stud. The arm needs to come outward. It's a 50 year old bike and goodness knows what has been reassembled with what. Maybe the arm is bent although it looks good?

[cado007]

Thanks Rotortiller Scotty and Hondaman
Unfortunately I am away from the bike until after the holiday.
I am hoping to take apart and find that number 7 is installed improperly and now I think I understand why that would make it recessed.
Before I left I did loosen the nut to see if that would make a difference and it did not but again I am hoping 7 reversed is what it is.
That would be pretty fortunate - It is going thru all gears now and goes into neutral easy so I think thanks to you guys I am on the right track
Unfortunately I won't be back to it for 5 days but I will report back and Thank you all Again
Best,
Damon

[Don R]

 I had one that shifted oddly and would shift from neutral into gear while kickstarting it, that is a thrill.
 That stud had a worn thread and the entire stack of parts was wobbly. I thought the case threads were worn out but when I tried to drill it for a heli-coil I realized there was already one in there. I got a different stud and loc-tited it in.
 It's shifted perfectly since then, just illustrates how important that little mechanical marvel is.

[HondaMan]

I had one that shifted oddly and would shift from neutral into gear while kickstarting it, that is a thrill.
 That stud had a worn thread and the entire stack of parts was wobbly. I thought the case threads were worn out but when I tried to drill it for a heli-coil I realized there was already one in there. I got a different stud and loc-tited it in.
 It's shifted perfectly since then, just illustrates how important that little mechanical marvel is.

And, I'd bet you already know what a PITA the K0 version of those things is to assemble: 3 hands would help, 4 would be great...

[Geoff Hastings]

My 1976 had the casing damaged by a thrown chain, the damaged case got pushed into the gears and locked the gearbox. I managed to lever the case back to its position and then weld up the case. The gears all functioned correctly but after a short test run there was a strange knocking noise from the box when the bike was on the side stand. Much as I didn’t want to take the engine back out I knew I had no choice. Fortunately with the engine out and the side cover off you can flip the engine upside down and remove the lower case without disturbing the top end. Mine turned out to be a small spacer that separates the gears had been left out from a previous engine strip.

[scottly]

And, I'd bet you already know what a PITA the K0 version of those things is to assemble: 3 hands would help, 4 would be great...

Hey Mark, the K7 version isn't any easier!! I took one apart the other day to refresh my memory, since it had been several decades since I'd done my K1.
I put it back together without the springs to check the alignment, and indications are the correct parts are assembled in the correct order on Damon's trans; note the exposed threads on the end of the shaft. If something was missing, there would be more threads, and if miss-assembled like I suspected there would be less threads.
Damon, I would bolt the cover back on and give it a try on the road.  

[HondaMan]

And, I'd bet you already know what a PITA the K0 version of those things is to assemble: 3 hands would help, 4 would be great...

Hey Mark, the K7 version isn't any easier!! I took one apart the other day to refresh my memory, since it had been several decades since I'd done my K1.
I put it back together without the springs to check the alignment, and indications are the correct parts are assembled in the correct order on Damon's trans; note the exposed threads on the end of the shaft. If something was missing, there would be more threads, and if miss-assembled like I suspected there would be less threads.
Damon, I would bolt the cover back on and give it a try on the road.  

Yeah, I'm still haunted by a much-abused K3 I rebuilt some years back: both the mounting post and the top roller-arm thingie were bent from some unspeakable event (which was probably why the trans cover itself was shinier than the rest of the engine?) and I had to also straighten the shifter arm: I didn't notice until 3 days after I walked away for a break & came back again that the threads below the hex nut on the post were at an angle, so when tightened the post was still tilted just a tiny bit. The whole thing looks tilted anyway, but I couldn't keep the little roller arm to stay up on the edge of the shift drum for nuthin'. Turned out it was also twisted slightly, putting the little wheel on the very edge of the shift drum's top plate, so it would fall off on every downshift attempt and lock the thing up. I was lucky in that I had a K7 engine on hand with a wrecked crankshaft that ended up donating its shifter stuff, which worked. That was a cold December project! I actually threw those bent-up pieces away at the end: I usually try to restore them or repair them, but I wasn't going thru that again with those. 

[cado007]

So I got back home and disassembled everything   - every thing looked correct -also bolt did not look bent - there is maybe a little less then 1/16th (end play)  on shifter drum if I pull out - I removed bolt in 2nd photo and spacer was the correct way
can I put a washer where the red arrow is to try to shim outward ?
Thanks
damon

[scottly]

A washer under  the outboard stepped bushing  will push it out, pushing it out will push the lever with the wheel out, pushing the wheel out will cause it to roll on the edge of the thick disk.

[cado007]

so just to be very clear put washer where black arrow is?

[HondaMan]

I can measure a set of those sacer parts that is sitting in a box with a disassembled engine here (awaiting rebuild) to make sure of the length of the 'stepped' bushing that holds this arm. The arm must ride on the edge of the shifter drum with its little roller, or else something is amiss. Back in a while...

[scottly]

so just to be very clear put washer where black arrow is?

Correct.
Mark, I already measured part #7, the stepped bushing. The overall length is .463", including the stepped end. The length of the fat part of the bushing, which is what sets the position of the arm, is .345". The OD of the fat part is .498", so the washer should be at least that size or larger.

[cado007]

well I put back everything and decided to ride it 10 miles. It is running great here is a video link - hope it works:  https://vimeo.com/manage/videos/1100882325  however I have to drive it in 2nd gear. I only putzed  around 10 miles in my neighborhood. It did not really want to go into 1st - mostly started in 2nd  - could eventually get into 3rd and 4th  not 5th -  would go back into neutral and neutral light works -false neutral in between 2nd and 3rd - think I may have to open bottom case - which will be a big job for me - but I have been wanting to get more involved in these engines. As stated previously I do have a 76 engine in my garage but that was given to me and I do not know how it runs- this seems to run well. I have some more seasoned guys I ride with that I am going to have ride it and see what they think. I am thinking and I am no expert - maybe a bent fork rod ?  I did adjust clutch, not sure if it could be clutch plates but I did adjust the clutch per manual and it feels good. I have a running xs650 so I can take my time on this - it just stinks cause it runs so nice and shifts so bad. thanks Damon

[cado007]

https://vimeo.com/manage/videos/1100882325