91
Frame / Re: Side stand
« Last post by Rex on 25.03. 2025 13:04 »Now if I just had the lug brazed on the frame tube...
View or Hide Header -->
Recent Posts
92
Gearbox, Clutch, Primary / Re: plunger gearbox
« Last post by Swarfcut on 25.03. 2025 12:19 » The rocking ball lever/selector arm is pressed onto the pivot pin, 67 3136. the front end is threaded to be drawn out, accessed by removing the gear lever shaft bush. Alteration of this pin is simply not an option, (it has to be a plain shaft for assembly) but the provision to move this closer to the camplate is an attractive idea, but a non starter however it is considered.
Same applies to the claw pivot, 67 3133, but welding up and redrilling more towards the camplate is another option. Simply a change of the selector arm may achieve the intended result if there is variation in this assembly.
For finding hidden dimensions as in such cases as this I resort to good old body filler and a dab of grease to stop it sticking. At least some distances are retained, unlike the old standy of BluTack or Plasticine.
Swarfy.
Same applies to the claw pivot, 67 3133, but welding up and redrilling more towards the camplate is another option. Simply a change of the selector arm may achieve the intended result if there is variation in this assembly.
For finding hidden dimensions as in such cases as this I resort to good old body filler and a dab of grease to stop it sticking. At least some distances are retained, unlike the old standy of BluTack or Plasticine.
Swarfy.
93
Frame / Side stand
« Last post by Slash on 25.03. 2025 12:03 »I was unable to find a side stand, so adapted this Suzuki Bandit one. Had to tap out the threaded side to suit the bolt, and sleeve down the other side. Put a stop so it didn't swing too far forward.
Works OK until I can find the original BSA part, but they are scarce; the Bandit stand is easy to find.
Works OK until I can find the original BSA part, but they are scarce; the Bandit stand is easy to find.
94
Gearbox, Clutch, Primary / Re: plunger gearbox
« Last post by RDfella on 25.03. 2025 11:17 »Following Swarfy's input, was thinking about how to cut out the guesswork and time spent fiddling around. Even if ultimately the gears work (gasket or not) one still doesn't know whether the pawl engagement is satisfactory or whether it's all operating on luck.
I appreciate these gearboxes are getting rare and they're not being rebuilt every day, but after an afternoon's frustration and still not sure if all is as it should be, I thought about how to ensure proper engagement. Given the engagement relies on so many machining operations being simultaneously accurate to a couple of thou using elderly machines and practices, I reckon that to avoid getting a bad reputation BSA must have assembled these gearboxes from bins of parts selected for fit. We have neither the jigs nor measurements to do that, so if ever I face that issue again, here's what I'd do:
1. assemble box case and cover using increasingly thick shims (say 3 x feeler gauges) until gear selection is compromised.
2. If shims are in the region of 2mm (.018" gasket + 1/16" engagement) then all is fine. Go ahead and assemble.
If not,
3. measure the depth of gearcase to cam lobe (say in 1st gear).
4. measure selector / rocker protrusion.
Then whichever of 1 or 2 is incorrect needs machining, but we need a few measured examples to determine which one.
There might instead be the option of making an eccentric selector pin, but I don't have the parts in front of me to tell.
Small addition - just measured distance to cam lug using a spare gearcase shell and a new cam I have - it's 1.510" at its highest between gears.
I appreciate these gearboxes are getting rare and they're not being rebuilt every day, but after an afternoon's frustration and still not sure if all is as it should be, I thought about how to ensure proper engagement. Given the engagement relies on so many machining operations being simultaneously accurate to a couple of thou using elderly machines and practices, I reckon that to avoid getting a bad reputation BSA must have assembled these gearboxes from bins of parts selected for fit. We have neither the jigs nor measurements to do that, so if ever I face that issue again, here's what I'd do:
1. assemble box case and cover using increasingly thick shims (say 3 x feeler gauges) until gear selection is compromised.
2. If shims are in the region of 2mm (.018" gasket + 1/16" engagement) then all is fine. Go ahead and assemble.
If not,
3. measure the depth of gearcase to cam lobe (say in 1st gear).
4. measure selector / rocker protrusion.
Then whichever of 1 or 2 is incorrect needs machining, but we need a few measured examples to determine which one.
There might instead be the option of making an eccentric selector pin, but I don't have the parts in front of me to tell.
Small addition - just measured distance to cam lug using a spare gearcase shell and a new cam I have - it's 1.510" at its highest between gears.
95
Chat, Offtopic & Everything Else / Re: The song that kicks you off
« Last post by muskrat on 25.03. 2025 11:15 »
96
A7 1946-1950 / Longstroke Camshaft
« Last post by Swarfcut on 25.03. 2025 09:30 » Picked up a used cam this week. Looks like a Longstroke and matches an example I already have stamped 67 695. But this recent purchase has no part number stamp, and more curious, is drilled almost all the way through on the long axis, similar to the A50/65 unit design. The gallery ends about 40 mm from the face of the thread, serving no purpose apart from lightness? But enables the possibility of modification to feed lubricant directly to the cam lobes, as more modern automotive practice.
Could be an aftermarket part, maybe one for Julian's archive. Still, it fits a pair of crankcases, turns smoothly and the lobes are in the right place. So if it looks like a Duck.....chances are it will do the job.
My researches show that two camshaft profiles were available for the Longstroke engine.
Swarfy
Could be an aftermarket part, maybe one for Julian's archive. Still, it fits a pair of crankcases, turns smoothly and the lobes are in the right place. So if it looks like a Duck.....chances are it will do the job.
My researches show that two camshaft profiles were available for the Longstroke engine.
Swarfy
97
Introductions, Stories, Meetings & Pictures / Re: What have you done with your bike/s today?
« Last post by Black Sheep on 25.03. 2025 07:57 »Took the Star Twin for a ride with the local Vintage Club. Did the usual of starting last and arriving at the lunch stop first - well, second this time as I did stop to take some photos and a guy on a TSS Triumph got there a minute ahead of me.
No, it's not a race but the idea of sitting in a queue of bikes at 50 mph (this was one of their quick days) doesn't appeal and they all slow down for corners.
Anyway, the bike is going as well as ever and all set for this season. It is possible to scrape the footrests with Cheng Shin and Ensign trials tyres so no rush to change them.
No, it's not a race but the idea of sitting in a queue of bikes at 50 mph (this was one of their quick days) doesn't appeal and they all slow down for corners.
Anyway, the bike is going as well as ever and all set for this season. It is possible to scrape the footrests with Cheng Shin and Ensign trials tyres so no rush to change them.
98
Chat, Offtopic & Everything Else / Re: The song that kicks you off
« Last post by BagONails on 25.03. 2025 07:16 »In case anyone's letting these road songs go to their head...
https://www.youtube.com/watch?v=HbhvZ2y1V80
a salutary lesson to us all hey, tho probs not so much the Beezer crowd
https://www.youtube.com/watch?v=HbhvZ2y1V80
a salutary lesson to us all hey, tho probs not so much the Beezer crowd
99
Chat, Offtopic & Everything Else / Re: The song that kicks you off
« Last post by Joolstacho on 24.03. 2025 23:41 »Haha, who said crime doesn't pay!
100
A7 & A10 Engine / Re: Rocker oil feed
« Last post by berger on 24.03. 2025 20:24 »i used to put my finger over many holes back in the day 
but now my bezaaaa has a bit of clear plastic tube and i see it going up---- i do honest , but i do miss getting my finger sticky now where's my black&tan 
but now my bezaaaa has a bit of clear plastic tube and i see it going up---- i do honest , but i do miss getting my finger sticky now where's my black&tan