Roller Rockers

Dkt26 · Aug 6, 2014

Has anyone ever fitted roller rockers to a commando or know of a product that suits?
Would they be advantageous over the stock rockers?
Am at the stage of putting a new head together and would like to keep my old one that was recently rebuilt as a spare ( once exhaust threads repaired).

Surely there must be someone who has done this mod???

Hobot · Aug 6, 2014

I and many others have looked for years for some small enough to fit but gave up as would require remaking engine to accept off the shelf roller rockers so you could be the first. Of of course once ya valve train to take 10K rpm on aggressive cam profile what good will it do ya? Got to have enough roller width to take the loads so would need exotic materials to stand it in the space available.

Nater_Potater · Aug 6, 2014

Going to a roller tip would preclude the ability to adjust the lash. The only way I can see around this is to have different thickness lash caps. What are you hoping to gain with roller rockers? If RPM is your game, you'd need to focus on the bottom end first.

Nathan

Hobot · Aug 6, 2014

Duh you'd want to use hydraulic roller rockers anyway : )

lcrken · Aug 6, 2014

There was a Canadian race bike some years ago with a 500 cc Norton twin that had roller rockers. Adjustment was by eccentric rocker shafts. The engine also had a one-piece crankshaft made from and Alfa Romeo crankshaft, and was regularly revved to very high rpms. I think there was an article about it in Classic Racer, but I don't have the time right now to sort through the back issues to find it. It was pretty slick, but, as Nathan pointed out, probably doesn't bring much to the game for a 7000 rpm Commando.

Ken

bwolfie · Aug 6, 2014

What is in Sir Eddy's setup? I know he threw the kitchen sink at it.

Dkt26 · Aug 6, 2014

lcrken said:
There was a Canadian race bike some years ago with a 500 cc Norton twin that had roller rockers. Adjustment was by eccentric rocker shafts. The engine also had a one-piece crankshaft made from and Alfa Romeo crankshaft, and was regularly revved to very high rpms. I think there was an article about it in Classic Racer, but I don't have the time right now to sort through the back issues to find it. It was pretty slick, but, as Nathan pointed out, probably doesn't bring much to the game for a 7000 rpm Commando.

Ken

I did see that 500cc setup but they were custom billet rockers that gave out and were abandoned. From memory it was a 10k rpm motor. Not after that.
Just thought that a roller setup might be a lot better if fitment was relatively simple.

pommie john · Aug 6, 2014

I can't see that roller rockers would really add much benefit. Roller lifters... that's a different matter.

Hobot · Aug 6, 2014

We all await the 1st successful ones.

DogT · Aug 6, 2014

Hey, those are my old valves.
Dave
69S

Hobot · Aug 6, 2014

Hehe, what a shame they left such a lasting impression on ya Dave. Grabbed em off google image as sure wouldn't want my own dirt laundery showing. Here drift off to sleep on this smooth action image

acotrel · Aug 7, 2014

How would you make the ends of the roller rockers lighter than the standard set-up ? My short stroke Triumph used to rev to 10, 500 RPM, I used the Wassell hollow tappets and cut the lock nuts in half. Even then the cams were of extremely long duration, slow lift rate and a lot less total lift than a normal race cam.

Nater_Potater · Aug 7, 2014

hobot said:
Grabbed em off google image as sure wouldn't want my own dirt laundery showing.

And, whatever you do, make sure you don't mention anything about rear-ending anyone! bad-day-yesterday-t20029.html

Hobot · Aug 7, 2014

On pre-peel and later Ms Peel i was still in the anti-wet sump gentle baby burping camp, ie: I'd start and let slow idle a min or so to warm up before blipping much or leaving but found scored stem tops on hardened caps with mushroom rockers and plenty of fuzz on sump magnet. On Trixie I got over it not being a flesh and blood infant and go straight to cam break in rpm on hopefully some wet sump and was pleased to hardly see any fuzz on sump nor hardly any evidence of burnishing on stock stems and rocker ends. Lifter faces finisher burnished than comnoz supplied to me. So I don't see much or any advantage in my sanely run Trixie and hope to get similar on my insanely run Peel in the works. Baz crash was punishment enough on its own w/o having negative reactions adding to his mood. I know the feeling too dam well.

lcrken · Aug 7, 2014

bwolfie said:
What is in Sir Eddy's setup? I know he threw the kitchen sink at it.

If my memory hasn't failed again, Sir Eddy's rockers used needle rollers on the rocker shaft, but no rollers at the valve tip, just a conventional adjuster.

Ken

acotrel · Aug 7, 2014

Perhaps Thackery washers have a purpose in valve gear by providing damping through slight friction and needle roller bearings in the rockers might be a step in the wrong direction ? Sometimes the theory might look good, however in practice ..... ? I shimmed the rockers in my old Triumph, and never had a problem. I never could be certain there was any benefit. Perhaps if I had been using a more dramatic cam, valve float might have occurred earlier ? I think with a Norton the bottom end collapses first.

midnightlamp · Aug 7, 2014

If you just fixed the contact geometry (which is actually embarrassingly bad) and run lighter rockers with mushroom adjusters and alloy locknuts you'd probably be more than fine. :mrgreen:

acotrel · Aug 7, 2014

What is the thread used on commando tappets ?

Hobot · Aug 7, 2014

Based on 26TPI 1 turn = 0.0385in.
0.006in~ 0.15 turns or 54°
0.008in~ 0.20 turns or 72°
0.010in~ 0.25 turns or 90°

Nater_Potater · Aug 7, 2014

midnightlamp said:
If you just fixed the contact geometry (which is actually embarrassingly bad) and run lighter rockers with mushroom adjusters and alloy locknuts you'd probably be more than fine. :mrgreen:

+1 Mr. Porsche used swivel-ball adjusters to great advantage, and that quickly translated over to the V-Dub engines as aftermarket items. My Triple has them, and the valve stems have always looked wonderful, as they spread the load and help correct for less-than-perfect alignment.
As for the alloy nuts, anything that can be done to lighten the valve train will help reduce wear/forestall valve float.

Roller Rockers

Similar threads