Blue printing B50 Gear Box by HPSTAN
First grind high spots back on cam plate face
If you have a mark here on the spring you have to check if the spring
goes down to the bottom of the slot. Look at the blue arrow.
If it doesn´t goes down to the bottom you have to grind away on the camplate.
Look at the red arrow.Rickard
Install the cam plate back in the cover. The same way you took it out
if you want it to shift the same way. ( Down for low up for second etc. )
It works either way, the shift pattern is just reversed.
If you have changed the cam plate spring LOOK HERE Rickard
Install only gear selector quadrant & cam plate in gearbox inner cover.
Install cover on motor so camplate is next to camplatespring.
Bolt shift lever onto shift shaft and while looking through mainshaft bearing hole,
slam shift through the gears and hold the lever at max travel.
I use a small halogen lamp bought at IKEA Rickard
This is how it looks.
The green arrow is the spring.
The blue arrow is the camplate
The Yellow arrow is where the spring should stop.
If the camplate is OK, the bump on the camplate spring will always
be in the same place in each gear.
If it ends up in the camplate slot sometimes and eiter ahead or after the
The plate is BAD!!
Throw it away and start over.
If the bump on the spring always ends up in the camplate slot, your home free.
If it always stops before the slot, you have to grind away on the crank case
boss that the quadrant hits against or on the edge of the quadrant itself.
If it always goes past the slot, you have to arc weld a glob on the quadrant edge that is to far away.
You have probably have to regrind some of your weld to get it just right.
Now assemble the complete trans.
Less the shim on the end of the main shaft that fits against fourth gear.
Install the complete unit in a junk set of crankcase from a B25, B44 or a B50 that you cut an
approx 3" X 3" hole in the top of the trans area.
Shift the transmission through all the gears and see if they fully engage.
Usually if you are going to have a problem here , it will be third gear
doesn´t fully engage.
To cure this you add a spacer washer between the main shaft bearing in the gearbox
inner case and first gear on the main shaft.
( once you set the proper thickness you should have to add a similar washer behind
the engine sprocket and a equally thinner washer next to fourth gear ).
Also check that you don´t have bent the shift forks by moving them
slide by each other.
Install an extra shift spring back up plate on your crankcasws and reinstall trans.
With these mods, it should be physically impossible to miss a gear with this thing.
Updated 22 May 2002
© Rickard Nebrér