revtothelimit - motorbike forum

If you have late rockers which don’t have an oilway drilled through them, but have a little scallop sliced out of one side, then a plain shim should be next to the rocker.

Study the rocker shaft. Would it benefit from a flat ground into it, to allow oil flow?

The square topped original Triumph adjusters have more dependable metallurgy than aftermarket Allen key ones.

You can just about see the scallops in the photos I posted.

I just looked, later spiral grooved rocker shafts are only £40 a pop so I think I'll get those.

You can use a 4” grinder on the shafts you have and save £80.

I've just ordered a boat load of seals and a new set of rocker spindles. Not including the spindles the bill - which covers every seal/gasket/washer from the top of the engine down to the base of the cylinders - was less than the cost of a single head gasket for my car. There's something to be said for the much simpler engines of the 1960s

I seized my Pre-unit 650 and fixing it was cheaper than a Ducati routine service.

I got the clean rocker boxes back from the vapourmatt cleaning place today. First job was to clean them in very hot water and then dry in a low oven to make sure there's no media left...I needn't have bothered, the cleaning guy did such a good job the water was still spotless after I'd finished! My bottle of engine build lube also turned up.



While I'm in here I'm swapping the rocker shafts to a new set made to the design employed by Triumph from 1973 onwards. The new ones have the extra spiral oil groove which gives vastly better oiling to the rockers. Oil comes up the centre of the shaft and then through those little holes in the narrow sections where the rockers actually sit....it then has nowhere to go in the old design. The spiral groove let's the oil out from under the rockers to oil the rest of the valve train. This improvement was actually designed in 1968 (my bike is a 69) as part of a package of changes, but political BS at Triumph meant they only introduced one of the three intended items on the 650 and actually made it worse! Fitting these post 1973/750cc shafts sets things how the designers intended.



Also got a bunch of properly old school copper and red fibre seals in the post.

A new copper gasket benefits from annealing.

Yeah you can see its just been stamped from sheet, its still got a sort of varnish on one side and very slight burrs from the stamping. I plan to anneal if with me auld camping stove! If that doesn't work its off to Wickes to get a blowtorch.

Any gas flame should do. It doesn’t all have to be red at once.

I tried to start rebuilding the rocker boxes today. Everything is clean now and I've got new seals etc.



I'd heard the task described as "like putting a cat in a toilet" and I'd say that's pretty accurate! Those spring washers need to be squashed almost flat and everything has to be aligned perfectly.

Sacked it off after an hour of trying. Will have another go tomorrow!

I know the rockers are upside down in that photo before anyone gives me that tip

It’s the sort of job mechanics do easily.

I’m not helping, am I?

From what I've read it was hit and miss if Triumph did it right anyway

Its a shitty job and you'll get nowhere trying to use the rocker shaft to align everything- you need a smooth piece of bar of the right diameter and even then I'd put a couple of hours aside

Nidge wrote: Thu May 20, 2021 10:11 am Its a shitty job and you'll get nowhere trying to use the rocker shaft to align everything- you need a smooth piece of bar of the right diameter and even then I'd put a couple of hours aside

Yeah I was thinking along similar lines, but you can't slide anything in from the other end to help with alignment 'cause the hole in the case it too small. Looking at my pic the hole in the right hand end is big enough to get the shaft in, but the one in the left isn't 'cause that's where the thread goes.

I suppose you can cut something down short enough to align the first rocker and then use the fact you've got the first one one in to align the shaft for the second?

Or maybe make a shaft which is a tiny smidge smaller diameter than the rocker shafts and tapered at one end. "Build" the rocker boxes with that shaft and then very carefully pull it out and hope you don't disturb anything before putting the real rocker shafts in.

Mr. Dazzle wrote: Thu May 20, 2021 9:31 am From what I've read it was hit and miss if Triumph did it right anyway

I think they consistently assembled the late design wrongly, for years.

At the last minute, you destroy the O-rings while trying to slide them into the holes in the covers.

Mr. Dazzle wrote: Thu May 20, 2021 10:42 am

Nidge wrote: Thu May 20, 2021 10:11 am Its a shitty job and you'll get nowhere trying to use the rocker shaft to align everything- you need a smooth piece of bar of the right diameter and even then I'd put a couple of hours aside

Yeah I was thinking along similar lines, but you can't slide anything in from the other end to help with alignment 'cause the hole in the case it too small. Looking at my pic the hole in the right hand end is big enough to get the shaft in, but the one in the left isn't 'cause that's where the thread goes.

I suppose you can cut something down short enough to align the first rocker and then use the fact you've got the first one one in to align the shaft for the second?

Or maybe make a shaft which is a tiny smidge smaller diameter than the rocker shafts and tapered at one end. "Build" the rocker boxes with that shaft and then very carefully pull it out and hope you don't disturb anything before putting the real rocker shafts in.

What Classic Bike magazine suggested -

I'm thinking either a bit of dowel or plastic rod would do it.

Thing is, I reckon you'd be able to fit a nice lead in chamfer on the spindle without compromising it. Oh well.

Yes I expect you can chase your temporary rod out with the spindle, wiggling the various washers, springs and rockers onto the wide sections of the spindle as you go.

There’s a special tool for getting the O-rings into the rocker box holes, but countersinking the holes might work better.

Whilst I ponder what to do with the rocker boxes I'm doing some more jobs. Tonight I cleaned up the push rod tubes and the push rods themselves.



The PRTs are from different years but they're both the same length and take the same seals. I believe the one on the left is a later design with superior retention of the 'wedding band' seal, so I may try and get another one like it. The pushrods themselves are very slightly different lengths (fraction of a mm), I don't know what's acceptable there. More investigation is needed!

The only thing left to do before I can start reassembly is to paint the barrels. I've cleaned them up with really hot water and I've got a can of Rust-Oleum gloss black high temp paint. Just waiting for some better weather now.