Alloy valve spring retainers

I popped the exhaust rocker inspection covers off my new toy today to pour a bit of oil into the head before starting
And found it has lightweight valve spring retainers
I'm not a lover of these I've had real problems removing one in the past from another bike when the collets dug in
Does anyone recognise this type? And are they any good?

Maybe Alloy-Tech

They look very much like my Norvil ones. I've had them for a very long time and not had any problems with them.

That baby looks like it needs a bit of rust patrol...

I have similar ones in my race motor, along with aluminium tappet nuts, dual rate springs and lightened rockers and yes, the collets are always harder to remove than in steel items. They are all totally unnecessary in a stock motor.

They not being necessary in a stock motor, I wonder what else yours contains?

hybridracer said:

They not being necessary in a stock motor, I wonder what else yours contains?

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It's supposed to be a 920 with a high lift cam ,I have no other details than that on the motor
I took a look in the spark plug holes with a bore scope
The pistons are flat top with valve pockets machined in
It's a mk3 engine
With MK3 chain cases running a wet primary belt with a RH change gearbox with double adjusters
It doesn't feel high compression to kick over to me
I drained the oil from the crankcase and added some oil through the rocker cover when I noticed the valve spring retainers
I once had to chain drill one of these retainers to remove it from a BSA B44 motor
The collets had dug in unbelievably tightly

Looks like a lot of money went into the engine so it was probably done correctly but you have to know what the cam is so the tappets can be set properly. Checking the existing clearances and lift might give a clue as to what it is.
I also have the Dunstall rocker covers on my Commando but don’t recall seeing any others ever. Nice.

I once had a '57 G80cs Matchless that had been hotted up by the long-departed Top Hat Cycle. Rather than hairsprings it had coils and some very light retainers. Maybe magnesium? The collets had dug into the retainers to the point that the retainers hit the bottom of the rockers, eventually holding the valve open a touch. Made it hard to start. I suppose if I had waited long enough they would have removed themselves, dropping a valve into the cylinder. Anyhow, being poor as a church-mouse, I fashioned new retainers from VW Bug retainers. It took a lot of work with a file but it worked. Those were the last alloy retainers I encountered.

It had the hot, sprint, CE intake cam and even with the VW retainers it would rev high enough to throw the windings off the commutator on the generator armature -- more than once. After the second time it was a total loss electrical system. With the tiny battery, I had about 20 minutes with the lights working to get home. May you fare better.

hybridracer said:

Looks like a lot of money went into the engine so it was probably done correctly but you have to know what the cam is so the tappets can be set properly. Checking the existing clearances and lift might give a clue as to what it is.
I also have the Dunstall rocker covers on my Commando but don’t recall seeing any others ever. Nice.

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I have them on mine too, only recently learned they were made by Dunstall. I also have one of his Dr. Blair designed 2-1-2 systems, would be called an X-pipe now I suppose.

MichaelD said:

I have them on mine too, only recently learned they were made by Dunstall. I also have one of his Dr. Blair designed 2-1-2 systems, would be called an X-pipe now I suppose.

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I too have a Dustall 2-1-2 and the rear sets,