CB72-77 Racer

lloydy1 · Post by **lloydy1** » Mon Jun 22, 2015 1:48 am

G-Man wrote:Lock the cam sprocket (I use a soft aluminium wedge between sprocket and case), then undo that big nut with a flat drift. Usually they are left hand thread....

That releases a taper and allows the cam to be separated from the sprocket. The other half is held with a taper headed drawbar a little like a bicycle steering stem fixing. Slacken the nut at the end of the cam and tap the bolt and you will feel the taper loosen.

With the sprocket released, each cam half is drifted outwards using a soft drift against the cam lobes. Heat the head first to slacken the interference fit on the bearings.

The inner bearing has to be driven out through the outer bearing aperture.

You'll get the hang of it.....

G

Thanks G. It is very much appreciated.

looking to take the castings to be vapor blasted today.

Cheers Dave

lloydy1 wrote:
Waveblaster wrote: Talking of cams....Being a novice concerning this engine..How do the cams come out??

The manual I have is pretty feeble concerning in-depth description.

Cheers Dave

lloydy1 · Post by **lloydy1** » Mon Jun 22, 2015 6:04 am

Hi

G you mentioned left hand thread on the lock nut. I am presuming looking at it as I have the picture that it would undo to the right. Not sure which end has the thread on and I don't want to just keep hammering it.

Thanks Dave

Waveblaster · Post by **Waveblaster** » Mon Jun 22, 2015 6:49 am

Lloydy

That splined nut is part of to the sprocket but can rotate to release the right cam . So from memory securing the sprocket and rotating towards the front of the engine clockwise loosens. (Left hand thread).

The small 6mm nut on the end of the left cam shaft can be loosened ( regular thread). I don't undo it all the way to protect the thread and tap it to release the tapered other end inside the centre sprocket hub to release the left hand half of the cam shaft splines.

Shafts and bearings need to be tapped out either side to release the sprocket then pushed all the way though the tunnels.

lloydy1 · Post by **lloydy1** » Mon Jun 22, 2015 7:03 am

Waveblaster wrote:Lloydy

That splined nut is part of to the sprocket but can rotate to release the right cam . So from memory securing the sprocket and rotating towards the front of the engine clockwise loosens. (Left hand thread).

The small 6mm nut on the end of the left cam shaft can be loosened ( regular thread). I don't undo it all the way to protect the thread and tap it to release the tapered other end inside the centre sprocket hub to release the left hand half of the cam shaft splines.

Shafts and bearings need to be tapped out either side to release the sprocket then pushed all the way though the tunnels.

Thanks Waveblaster. G did tell me it was left hand thread but I was unsure which way he may have been looking at it. Cheers Dave

lloydy1 · Post by **lloydy1** » Mon Jun 22, 2015 7:35 am

Cant get this lock nut to undo!!! broken a tooth of the cam cog trying...:o( Ill have to get it to someone who has a bit more know-how than me.

LOUD MOUSE · Post by **LOUD MOUSE** » Mon Jun 22, 2015 8:08 am

If you have vise grip pliers get a grip on the tapered side of the sprocket (other side from lock nut.)
Put the pliers to the front of the head.
Use a flattened tool to drive the nut to the right.
Hit it hard!. ....................lm

lloydy1 wrote:Cant get this lock nut to undo!!! broken a tooth of the cam cog trying...:o( Ill have to get it to someone who has a bit more know-how than me.

G-Man · Post by **G-Man** » Mon Jun 22, 2015 10:13 am

Dave

It's not impossible to find a right hand thread nut. Very rare but not impossible.......

G

lloydy1 wrote:Cant get this lock nut to undo!!! broken a tooth of the cam cog trying...:o( Ill have to get it to someone who has a bit more know-how than me.