Roller Rockers

grandpaul · Aug 7, 2014

I seem to recall early press on the new Norton mentioning roller valvetrain components; "NASCAR technology" I believe is how they worded it.

I wonder if they made it to the final production models?

lcrken · Aug 7, 2014

This is a picture I douwnloaded from somewhere in 2012, showing rollers on the tips, so I assume they made it into production.

Ken

Hobot · Aug 7, 2014

Ken what a pretty picture but what did it gain performance wise?
I forget what contact kit Peel has hard caps? and thought the mushrooms may wiped off too flat after the stuck throttle.

acotrel · Aug 7, 2014

I've seen those tappets with the balls in the ends somewhere. Do you know of any which might fit the commando ? The only thing I can think of against using them is a possible weight problem. At the ends of the rocker arms extra weight can have a bad effect. Still a commando does not really rev that hard.

chilly · Aug 8, 2014

I have some elephant foot type adjusters on my Triumph which work really well , very pleased with them , they have done thousands of miles with very little wear 8)

Not sure if they are available for Norton tho :?

SteveA · Aug 8, 2014

chilly said:
I have some elephant foot type adjusters on my Triumph which work really well , very pleased with them , they have done thousands of miles with very little wear 8)

Not sure if they are available for Norton tho :?

I assume 'elephants foot' is equivalent to 'mushroom' , which are available from RGM.

john robert bould · Aug 8, 2014

Its a 916 head.

lcrken said:
This is a picture I douwnloaded from somewhere in 2012, showing rollers on the tips, so I assume they made it into production.

Ken

SteveA · Aug 8, 2014

hobot said:
Ken what a pretty picture but what did it gain performance wise?
I forget what contact kit Peel has hard caps? and thought the mushrooms may wiped off too flat after the stuck throttle.

I would assume they were looking for longevity rather than 'performance'......

Modern expectations of 'service life' are different to 'ours', due to things like synthetic oil with extended change periods and Iridium spark plugs that can last 100k with people never expecting to replace them!

acotrel · Aug 8, 2014

Looks like the 916 was designed not to rev any higher than the old commandos ?

acotrel · Aug 8, 2014

An old thread:
floating-balls-anyone-used-them-t9081.html

chilly · Aug 8, 2014

SteveA said:
chilly said:

I have some elephant foot type adjusters on my Triumph which work really well , very pleased with them , they have done thousands of miles with very little wear 8)

Not sure if they are available for Norton tho :?

Click to expand...

I assume 'elephants foot' is equivalent to 'mushroom' , which are available from RGM.

Yep! thems the ones

lcrken · Aug 8, 2014

hobot said:
Ken what a pretty picture but what did it gain performance wise?
I forget what contact kit Peel has hard caps? and thought the mushrooms may wiped off too flat after the stuck throttle.

Beats me. Less friction loss due to rubbing at the valve stem tip, but at the cost of more mass at the rocker end. My best guess would be that it's mostly to eliminate wear on the end of the valve, leading to less frequent clearance adjustments. Maybe less side force on the guide, meaning longer guide wear life. But that's just a guess. It's pretty normal technology now for modern high performance pushrod engines, so maybe there are other reasons that escape my penetrating analysis. IN any case, it certainly looks like a sturdy rocker arrangement.

Ken

john robert bould · Aug 8, 2014

performance was the last thing wanted, and deffo not rev's. just a nice Norton transfer on the tank. Haven't heard much for a good while..are they.....?

acotrel said:
Looks like the 916 was designed not to rev any higher than the old commandos ?

acotrel · Aug 8, 2014

It is still possible to get plenty of performance without revving the tits off a motor as big as that. I don't know whether the 916 uses a centre bearing in the crank, and if you were looking for performance through making the motor top end, you would make the motor with the same valve configuration as a Weslake or a Paton. Sort of defeats the purpose of making a retro bike ?

lcrken · Aug 8, 2014

acotrel said:
It is still possible to get plenty of performance without revving the tits off a motor as big as that. I don't know whether the 916 uses a centre bearing in the crank, and if you were looking for performance through making the motor top end, you would make the motor with the same valve configuration as a Weslake or a Paton. Sort of defeats the purpose of making a retro bike ?

It does have a center main bearing, and the crankshaft is pressed together with one piece rods.

Ken

acotrel · Aug 8, 2014

I often wonder how close people got to achieving the full potential of the old commando design. To my mind it runs counter to all the theories of what a high performance engine should be. That is the reason that when I built the Seeley 850 in the late 70s, I did not race it. I simply could not believe it would cop a beating or be fast enough, and in any case I was doing other things. When I ride it these days, I am amazed just how good it is. That photo of me on the right, was taken at Mount Gambier in the late sixties. Back then there was a guy there with a commando who was extremely quick and competitive. I always thought it was the circuit and the big engine which made him fast. The circuit was covered in non-skid, and you could grab big handfuls of throttle everywhere almost with impunity.

Roller Rockers

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