1970 S: a hole between 2700/3000 rpm

Read the Old Britts page on gearbox assembly, especially about installing the spring 04.0038. http://www.oldbritts.com/gearbox_a.html The spring can really mess things up if not installed correctly. The spring is about 3/4 down the page.

pierodn said:

But, after 15 km., the bike have lost the shift gear, the lever (well tighten into the shaft, went up and down but with no changement of gears.
Thank you.
Piero

Click to expand...

New thread needed as we are now seriously off topic

Hi.
Changed with new "gearchange return spring", rachet spring, gearchange ratchet spindle and o ring.
The first gear engage but impossible to go in neutral and over.
Mooving the gearchange indicator bolt with a spanner is easy to go from first to neutral and then the lever shift well from neutral to fourth and back, but you do not engage the first because you remain in first.
If i moove the gearchange indicator bolt with a spanner the four gears and neutral engage great.
I have rebuilt more than ten gearbox without problems, so i cannot understand what happens!.
Suggestions please?
Thank you.
Piero

pierodn said:

Hi.

Mooving the gearchange indicator bolt with a spanner is easy to go from first to neutral and then the lever shift well from neutral to fourth and back, but you do not engage the first because you remain in first.
If i moove the gearchange indicator bolt with a spanner the four gears and neutral engage great.

Suggestions please?
Thank you.
Piero

Click to expand...

This can only be a ratcheting problem. Did you read my post of July 12?
I had almost identical symptoms with my gearbox which caused me to remove the outer cover several times only to confirm that everything was correct, or so I thought.
Finally I noticed a shiny mark on the new pawl where it had been dragging on the ratchet plate as it returned to centre. This caused the ratchet plate to move back slightly so that, the next time the gearlever was moved, the pawl missed the next tooth on the ratchet and no change of gear occurred.
This sounds very much like what you are experiencing.
After grinding a little bit off the pawl to stop the drag, my gearchanges are now perfect every time.
Before that, my gearbox was unuseable.

I had the same problem on my BSA Lightning. It was the Pazon Altair ignition. Sent it back to Australia. They couldn't find anything wrong but they replaced it anyway with a newer version and all is fine now. It would start crapping out at 2700 and then come back at 3000-3100. This was after rewiring, new Premieres (which are great) a new battery and regulator..... the long way around.

ToddK

Flat Spot .

Check the auto advance ( ignition ) unit . May be sticking . Check the action is steady // free . No graunches .

differant rate springs vary things . Most Lucas ( auto ) springs are similar .