650 ss tappett adjustment

hillbone

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Hi again.
When adjusting my tappets, I would have imagined that approximately the same amount of thread on the adjusters would measure the same. But there is a big difference between the 2 inlets left and right and the same with the exhaust. When refitting the head, i triple checked each pushrod and dropped nicely into cam followers and each pushrod is correctly seated into each rocker. 2x
My logic tells me the thread adjutment should be roughly the same.
Thoughts please.
Cheers
 

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Hi again.
When adjusting my tappets, I would have imagined that approximately the same amount of thread on the adjusters would measure the same. But there is a big difference between the 2 inlets left and right and the same with the exhaust. When refitting the head, i triple checked each pushrod and dropped nicely into cam followers and each pushrod is correctly seated into each rocker. 2x
My logic tells me the thread adjutment should be roughly the same.
Thoughts please.
Cheers
Did you checked the lenght of both pushrods ? as the pre 125871 are 2.5/3 mm longer than later one ....
 
Is this a new build? If not the ball/nubs on the adjusters may have worn into the valve stems. Years ago in the shop I would put hardened lash caps on to rectify this problem. Otherwise customers were on the hook for a valve job if the stems were too bad.
 
Is this a new build? If not the ball/nubs on the adjusters may have worn into the valve stems. Years ago in the shop I would put hardened lash caps on to rectify this problem. Otherwise customers were on the hook for a valve job if the stems were too bad.
Hi. No its a rare paul dunstall delivered new bike, very low milage that was featured on the cover of classic bike magazine. But the last owner really messed with it and fiddled with just about everything. Im thinking of tearing it down from scratch and starting over. Im not new to nortons as ive had quite a few from 40 years back. Thanks mate.
 
Hi again.
When adjusting my tappets, I would have imagined that approximately the same amount of thread on the adjusters would measure the same. But there is a big difference between the 2 inlets left and right and the same with the exhaust. When refitting the head, i triple checked each pushrod and dropped nicely into cam followers and each pushrod is correctly seated into each rocker. 2x
My logic tells me the thread adjutment should be roughly the same.
Thoughts please.
Cheers
If the valves all open an close and you don't hear anything odd, you're probably OK. Also, hard to tell form the picture angle, but the adjusters look like they are different lengths - take a look at all four and see if they are the same lengths or not.
 
If the valves all open an close and you don't hear anything odd, you're probably OK. Also, hard to tell form the picture angle, but the adjusters look like they are different lengths - take a look at all four and see if they are the same lengths or not.
All adjusters and pushrods same lengths. As in, the inlets are same etc.
 
Agreed the lengths are slightly different from the 650 to the 750 atlas. Also wondering if the height of the tappet lifter blocks at the bottom of the cylinder are set equally and parallel.

Not sure if Dunstall would have used the standard issue tappet block, or would have swapped them for something like the BSA Lifters similar to the ones that Jim Schmidt sells.

looking at the photos too, it almost looks like one of the rocker arms is thinner than the other. Is that just my eye? The arm with the adjuster bottomed out looks polished considerably thinner than the one in the foreground.
Just a thought.
 
Valve stems 0.1" longer after a certain engine number to " improve " valve action . Messed up one of my adjusters as should be used with shorter pushrod .
 
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