[simstro]

Hi all, (first post on here so I hope I am doing this right)

A little history first: I bought a 1970 Honda CB350 a year ago in pieces. Put it all together and found out it had a few engine issues and the transmission worked except I could never get it into second gear. It would always grind when letting out the clutch in second but then I could shift up to third and it would go in just fine. So I split the cases only to find everything is perfect working condition. No broken pieces or anything visibly wrong. So I put the cases back together, rebuilt the top end, reinstalled everything and took it for a test ride last week.

Here is where things get interesting. Everything worked fine except now I couldn’t shift up (past neutral) at all. So I took off the right side cover and clutch basket so I could watch it shift and see what was happening. Everything there seemed to be functioning correctly and to my delight I did find out I could shift up into second and so on if I used a screw driver to turn the gearshift drum. Down shifting works perfectly though.

So, the issue is I can manually shift up if I use a screwdriver but if I use the shift lever on the bike it always only turns the gearshift drum partially and never all the way so as to prevent it from shifting into gear. Attached is a picture showing what I am talking about. Any ideas as to why I can manually shift things but the lever won’t work when shifting up? Let me know if more information or pictures would be helpful. Thank you all

 

[Boomer343]

Constant mesh transmission .... has to be turning in order to shift through the gears. The transmission can also get bumped into a locked situation and mimic a seized engine.

 

[DD23]

Could you post another picture showing more of the mechanism to the left and right please ?

I asume you have a manual ?

CMSNL.com exploded views are very informative.

Even a thin shim washer missing can cause gear shift issues, even broken gears.

You sure the detent roller is not miss aligning ?

There is also a detent neutral ball and spring...

 

[PoiPio]

If you found no fork arms or the C area of the fork being burned, no gear dogs on second missing or badly bit off, and manually shift it, can get into third, back to first and N, I think you're good.

This is going to sound strange, but it may have an idiosyncrasy like an engine does starting. Meaning, it wants to be shifted like this. And that means to find it. Like I find with engine starting. My carb bike does not want a choke starting cold. Turn the key, fires right up. That's what the bike wants is no choke. That kind of idio if you will.

 

[grumpyunk]

I do not know the names, but the flat plate that actually interfaces with the teeth of the shift drum likely has wear, or the teeth on the shift drum have wear. If I understand, the 'tooth' for second gear position is always the same tooth that the shift plate interfaces on upshift, and downshift. If it can be shifted using a Philips (JIS hopefully used) screwdriver, then the toothed plate should be able to do the same. Actually the torque required by using a screwdriver is a little high, so the shifter would have an easier time providing it given the mechanical leverage of the external lever to push the shift plate back and forth.
I think the damaged portion of the end of the shift drum has been moved one tooth in rotation from where it was before, and you now are finding the problem has moved one gear down (from 2nd to N).
I would remove the shift mechanism(contraption) and inspect the teeth of the gear(?) that the flat link grabs onto to up/down shift. Making the assumption that same gear was rotated when it was put back onto the end of the shift drum. It may be wear, as in the 'hook' that pulls/pushes on upshift/downshift is not moving the drum sufficiently for ONE position to be engaged fully. Or disengaged fully. So, it was trying to go to 2nd, not getting fully moved by the shift linkage(but screwdirver does), and made graunching sounds. Now, moved tooth, and it does not like leaving neutral... the 'failure to move sufficiently' problem has followed the tooth ... maybe. It is either that, or the shift forks fit to the shift drum is too loose, allowing the linkage to move it partially, and thus partially engaging the dogs, on both up/down shift. The fork actuating end piece can move a bit in either direction within the groove, but not enough to engage/dis-engage. Ya think?
tom

 

[PoiPio]

Elongated riveted washer resting on the star-washer. Claw arm moves... taking out the slack first of the worn washer hole?

I do love my JIS T-handles... Justice Is Served... if you don't.

 

[grumpyunk]

I have not taken one apart in a while to know exactly what is under there, but to my mind,, the claw has too much slack, and is not rotating the drum enough. Wear or slop or missing parts or assembly parts order not exact.(washers swapped, or out of position, etc). Either way, I think it is too 'slack' and the slack is likely moving with the assembly positioning on the shift drum. I know not the actual names.
tom

 

[PoiPio]

Taken apart in awhile is a half a century cracking one of these eggs open. See if you agree if I list it out.
He has the bike's trans out and back in. Can't close the case, can't shift the trans if you could close the case. But this is not the case. You'd think I'd let that pun go?

The linkage can only be assembled one way as like the trans and just say every last bolt on the bike. We are up to this point of the claw throw. The claw system can't wear that much as a riveted washer. The claw is spring loaded and returns to center each time.

The only thing I used to see were the riveted washers elongating. The OP can get each gear, each gear can hold in place under load, especially second and that longer throw is because of N between 1-2.

That's the OP's complaint. I wonder if shifting faster to 2nd would find that idio?

 

[grumpyunk]

OP has not been back to comment, so likely it was taken to a shop and someone there is having fun doing the Dx. I am not very punny, so may have totally missed it.
I do not know the riveted washer, but more or less figured there was a 'star' or 'toothed wheel' bolted to the shift drum, and said teeth were likely worn in one spot, leading to incomplete shifts. I suppose starting in 1st, and then shifting hard into 2nd to get past N may have caused that particular tooth to wear more, thus leading to the inconsistent shift failures. Moving the teeth one notch on the drum changed which shift was having the problem. Sounds shifty to me...

 

[simstro]

Hey all, thanks for the thoughts. I did figure out the problem finally. Luckily and to my stupidness, I had installed the gear shift wrong. It was a spline too far counterclockwise on the shift rod so instead of turning the rod it was pushing against it. So once I adjusted and correctly installed the gear shift, everything shifts fine! Looks like it was just a rookie mistake on my end 🤦‍♂️