1970 S: No engage from First gear forward

Hi.
The bike has run great for 3.000 km from restoration.
Now the gearbox lever from neutral goes easily to first gear but doesnt return to neutral and down to the second, third, fourth (the lever mooves down, but no engages).
With the bike running mooving the gearchange indicator bolt with a spanner from the first is easy to go to neutral and then to forward and back from neutral to fourth.
But if you go to the first, that engages easily, you cannot find the other gears.
I have replaced a new "gearchange return spring", gearchange "rachet spring", "pawl carrier assembly", "oring with new ratchet spindle": i havent changed the "gearchangeratchet plate".
If i moove the gearchange indicator bolt with a spanner the four gears and neutral engage great.
Note that when the bike is on the stand the gears engage all great, first, neutral, second, etc.!!!!! but not when you ride!!!!!! N
I have rebuilt more than ten gearbox without problems, so i cannot understand what happens!.
Suggestions please?
Thank you.
Piero

I had that also. I left off the gear change indicator because it blocked the gear lever shaft when tightend.
The inner shaft must rotate freely.

rivera said:

I had that also. I left off the gear change indicator because it blocked the gear lever shaft when tightend.
The inner shaft must rotate freely.

Click to expand...

Hi.
The inner shaft rotate freely.
Also Without the gear change indicator the problem remains.
Piero

mine also selects nicely when not moving but was stiff in operation when moving, I've found the it changes smoothly when the throttle is blipped before change

" If i moove the gearchange indicator bolt with a spanner the four gears and neutral engage great. "

Is it possible that the gear change lever is slipping on the shaft? Or peut-etre the splines are worn out, so the lever moves but the shaft does not?

Piero, make sure that the bracket bolted into the outer cover which holds the large spring in position is not fouling the selector when it is fitted. This bracket should allow the selector to have full movement up and down without the selector rubbing on it anywhere, if it does simply loosen the two mounting bolts and adjust it a bit. Also make sure that your primary chain is not too tight as this can cause gear selection problems.

Sticky clutch or loose mainshaft nut ?

dave M said:

Piero, make sure that the bracket bolted into the outer cover which holds the large spring in position is not fouling the selector when it is fitted. This bracket should allow the selector to have full movement up and down without the selector rubbing on it anywhere, if it does simply loosen the two mounting bolts and adjust it a bit. Also make sure that your primary chain is not too tight as this can cause gear selection problems.

Click to expand...

Hi Dave,
nice to hear from you.
The large spring is new replaced.
I can only replace the ratchet plate.
All the other parts replaced.
The strange thing is that the gearbox with the bike switch off on the stand works great.
The problem happens when it runs!!!!
Regards
Piero

Greetings Piero,

It is not the big spring that I am talking about but the bracket that holds the big spring in position, this bracket is often removed for polishing and when it is put back it can interfere with the selector mechanism if it is not bolted back while checking that the selector mechanism can move freely all the way up and all the way down, the bolts can can also come loose and cause problems.

Hi Piero, as said above , if it happens only when running , it could be your mainshaft not tighten , either on the clutch side or on your gearbox side , I just say could be ........check , and report!

marinatlas said:

Hi Piero, as said above , if it happens only when running , it could be your mainshaft not tighten , either on the clutch side or on your gearbox side , I just say could be ........check , and report!

Click to expand...

Hi.
I will check and report.
But the clutch side has a belleville washer!.
Thank you.
Piero

It works.

Not knowing what to do more, with the engine off, I started to push the bike back and forward pushing with destructive force the shift lever by hand, from first to fourth by selecting all gears.
Well, now the gears engage perfectly and smoothly.
I did before!
Bah!
Piero

Don't argue with success.