classic motorcycle forum

probably  a selective fit  in original manufacture ...always a problem when you  no longer have a wide selection of parts to chose from ..........i recall   something  like that with IH  truck  gearboxes when I jammed a tight first gear onto the mainshaft  hoping it would free up in use .....it   was  too tight  to  change gear ,and so never got a chance to free up.........and I got a  kick   up   the jaxi  from the boss.

Most likely cause of jamming is burred first tooth on the starter quadrant .......first meshing tooth should have a sharp point .....when it gets burred ,the traditional cure was to grind it off and sharpen the next tooth...........ditto the mainshaft ratchet gear ...it should have pointed teeth ..........I d also add ,you never stab at the pedal,mesh the gears first before applying pressure ...........The 1956 on  AMC box has the Norton style kickstart with a sprag engaging an internal rack ......reliable and near abuse proof.

The toolbox is correct for the plunger frame ,its odd its mounted cockeyed .........BSA had the forge shop to make the frame ,a part of their heavy weapons plant..........BSA also drop forged the flywheels ,even the lowly side valves had forged steel flywheels........in fact you can make a very capable OHV from a BSA M20 or M21.

The motor leans forward because the original motor had the magneto at the front ,with space at the back of the crankcase ...........the mega dollar BSA ohv V twins use the same frame backbone ....J 12 and Y 13 ...and sell for mucho dollars

Pull the gearbox to bits .....the whole joy of old bikes is pulling them to bits and putting them back together again.

A pre 36 maggdyno will have a ring cam ,and quite often these rings are very worn,altering the timing adversely..........you cant regrind the ring ,as its case hardened ,and once the hardening is worn thru ,very soft steel.

A late A10 should be alternator with the 4 spring Triumph cluctch....not the six spring pressed tin BSA clutch...........anyhhoo,people replace the clutch with a Suzuki one ,cant recall which ,but the swap is well documented.........Incidentally the dragging clutch will smash your gearbox gears apart.,and sharp gear chips will score the shafts.............To cure this problem ,I fitted an army beezer clutch ,this freed easily,but tended to slip under power.,just had to ride the bike sedately .............Anyhoo,when I sold the bike ,it lasted only one day , and was on the news that night..........he tried to pass a bus on the inside as it turned left .

Fail to start can also be flooding of a hot motor ...........I diagnose start problems with a can of starting spray ......this stuff will fire with flooding or with fuel starvation .......but it wont fire with no spark.