Britbike forum Forums British Motorcycle specific Brands Triumph bulletin board Improve oil to rocker boxes Triumph pre unit twins

It is all a matter of (increased) engine performance in combination with life time of components.
Many (non-Bitish)bikes have a pressure feed to the top-end directly from the discharge of the oil pump to lubricate rockers/spindles, valve tips/adjusters and valve stems.
My 1955 T100 (and I think many other pre-units) have no oil ways in the rockers leading to the valve tips/adjusters, so these are totally depending on the oil seeping from the clearance between spindles and rockers and flung around by the motion of these components, no capillary action can bring oil to valve tips and stems.
The push rod tubes can easily handle the approx. double oil flow corresponding with ca. 1 barg feed pressure.
Now at least I can see oil at the adjusters, where before installing the pressure control, there was hardly anything to be seen.

The valve tips are oily when the engine is running. If they were submerged in gallons of oil the lubrication effect would be much the same. Heads with a lot of oil need valve stem seals to hold the oil back. The main potential benefit from extra oil would be cooling. I don't think you'll see any such benefit, but the potential must be there!

If you want long lasting valves and guides, avoid low priced pattern (or even original) parts. Get modern items, such as Kibblewhite.

Modern OHC designs need pressurised lubrication.



That may improve your valve watching experience more than it does your riding experience. Good luck and everything, but I strongly suspect that, if your modifications "work" by putting much more oil up there, it will do more harm than good. Keep us informed, please.

sonnehaerdt:

To your point did you use a good quality assembly lube on the valve tip/adjuster face during assembly?

You didn't happen to test turn over the engine during assembly without any oil on the valve tip/adjuster face?

All the pressure increase available will not overcome the fact that on 1969 and later 650 rocker shafts there is no way for the oil to be distributed to the push rod or valve tip! Then in 1973, when they finally cut a spiral the length of the shaft did the oil have a path out of the center of the rocker, but the wrong placement of the spring washer insured that the valve tips continued to get little, if any lubrication.

The lubrication on the 1969-1972 650 models was not that much different than the exposed valve spring Norton pictured above.

Hello John,

I use a stuff called TSL in concentrated form and pour some oil (Penrite classic 30)on top of the valve tips/adjusters/rocker arms before moving any part and boxing up (knowing it takes some time for the oil to reach these places after starting).

The whole top lubrication system looks marginal to me compared to some other (non British) makes of the same aera (fifties/sixties).So this explains in my opinion the frequent adjustements and rather fast wear.
Another probable reason why this nevertheless functions reasonably is the fact that when the engine is hot there is some oil mist/vapour around.
One more thing that could play a (negative) role is that the oil scavening pump has a bigger capacity then the supply pump, hence the bubbles in the oil return system. Once a put a clear hose to the rocker spindles and it was evident that there is oil and bubbles going slowly up there.
I will now wait and see whether my improvement brings something on the long term (say some 5000Km)

Take a long look at the relationship between the hole in the rocker arm and the turned down section of the rocker shaft. What do you see?

Have you looked yet? Trace the path of the oil. How does the oil get from the turned section of the rocker shaft to the hole in the rocker.

How will all of your extra oil flow, and get out the ends of the rocker arm?

What did they do in 1973 to improve oil flow to the top end?

It is simply a matter of hydraulics: if you increase the pressure with a factor 4 (so from about 0.25 bar to 1 bar)the flow through a given restriction (the clearance between rocker shaft and spindle) will be twice. Nevertheless two times a very little amount is still rather little (but visible).

Put a tank of fuel through your bike at full throttle, then let it idle for an hour, then tell us your system works.

sonnehaerdt:

What did Triumph do to increase flow with the introduction of the T140? Hint, they didn't increase the pressure...

In the development of the Triple, changes were made to increase the flow of oil to the rocker box. The traditional drilled rocker arm was abandoned. The drilling is actually blocked by the rocker shaft. The hole has very restricted access to the oil galley formed by the reduced diameter of the rocker shaft. It is limited by the amount of oil that will pass the .001" clearance the rocker has on the shaft.

What replaced it the original rocker was one with no hole. The ends of the rocker arm eere chamfered to create an oil galley, and a slot milled to allow the oil to flow down the side of each arm of the rocker. The order of the outer thrust washers were reversed placing the flat spring next to the rocker and the spring next to the rocker box. A slot was then cut the length of the rocker shaft to provide a place for the oil to flow along the shaft and out to the ends of the rocker. This put enough oil out the rocker box to require the guides be fit with valve guide seals. There is a bit more to it, but that is the idea. So it was to be for the triple.

The rocker box you are working on has no provision for the oil by-passed from the return oil line to flow any where, at least in any quantity. If you remove the dome nut retaining the over head oil line you will flood the top of the engine with oil. But with the dome nut tightened on very little makes it into the box itself. There is just too much restriction to allow it to happen. There is enough oil to keep the rocker arms from seizing to the rocker shafts, but little else.

To make things worse, the hole in the rocker arm that is supposed to feed oil to the push rod cup doesn't even open into the oil galley formed by the turned down section of the rocker shaft. What little oil that gets to the rocker arm has to pass through the .001" clearance between the shaft and the rocker. Just lengthening the galley, so that the rocker hole has direct access, would do a lot to increase oil flow.

So move ahead to the time when the guys at Umberslade Hall were developing the triple. That was when a group of "whiz kid" engineers, fresh out of school, were in charge of engineering. They must have looked at this and thought they could do better. The new rocker arms developed had the oil hole omitted. The inside edge of the rockers were chamfered for oil passage, a groove cut, to allow directional flow, cut into the side of the rocker body and a slot cut in the rocker shaft itself so oil could flow to both ends. They then reversed the flat and thackery washers with the flat washer helping direct oil toward the valve tip and push rod cup.

In and around the same time they must of thought that this would be an improvement on the 650 twin. The new rocker arm design found its way into production, but without the grooved rocker shaft and the washers remained as they had been for 30 years. Actually when you think about it, on the twin it was a step backward. The 650 twins remained in this condition until the introduction of the T140/TR7. They finally cut a spiral groove in the rocker shaft. Alas though, those clever lads on the assembly line still got the thrust washer and thackery reversed. What did those kids know any how? "We have been doing it this way for 40 years!"

So if you want more oil to flow through the rockers, either lengthen the oil galley on the rocker shaft or get a set of T140 rocker shafts (or cut a groove in you old shaft) and reverse the thrust washer and thackery. If you choose to use your old rocker arms you will have to grind a chamfer in the end faces of the rocker and cut a small path to direct the oil toward the valve and push rod.

There, I think this reads better...
John

Thanks for this extensive explication.
It confirms that pre units (like my 1955 T100)and some later models for rocker ball pins and valve tips/adjusters lubrication totally depend on the oil coming from between the spindles and the rocker.
Of course having appropriate oil ways in spindles and rockers as later developed (I assume for good reasons)as you described would be the ideal modification.
However this takes more time and cost than simply increasing the pressure a bit the way I did.
(Most likely the clearance between the spindle and the rocker is a bit more than 0.001" on my old machine, so the oil comes out somewhat more easy).
Anyhow I consider it better than restricting the hole in the return pipe in the oil tank by a piece of wire, a temporary thump or alike. On top of that there is always a minimum pressure of 0.7 bar regardless the rev's (the pressure build up via the hole at low rev's is very low)
So far it works fine.

So now you need modify your shaft and rocker arms, or find a set of used T140 shafts and rockers to replace the one you have now. You might as well increase the flow, which will reduce the chances for an oil leak at a higher pressure. This will give you a real increase in flow of oil to the rocker box.

No need for that, I am happy the way it functions right now: no leaks and sufficient oil.

That's what mine's like too. That's with no modification.

We're all happy as a sandbag.

Will a T140 shaft fit a 650 rocker box (assuming you use the UNF acorn nut)?

Yes.

If the rocker arms are drilled, use the existing thackery and thrust washer setup. If the rocker arms are solid with the machined divot, you need four (4) thrust washers with 1/2" ID assembled in the correct sequence with the thackerys.

Steve

I so appreciated this thread, especially John Healy's insights and recommendations, that I tried to synthesize it into two useful pages that I could hyperlink to my parts catalogues. So, sharing this link to my PDF here thinking this might be a useful reference for other folks as well.

https://drive.google.com/file/d/1HXx6CAx_BrjJNpx-5iYmN4N-OIXTNIO3/view?usp=sharing

Thanks for sharing Mike, I've saved the PDF in my Tech Files.
I've done the shim re-arrangement for many years now, since I first learned about it.
Wish I had known about it in my younger days, when I rode my 71 Bonnie around 100.000 miles...
But seriously, I did experience squeaky valve gear at times, and valve and guide wear. I now believe that a correct shim arrangement, and scrolled rocker shafts would have eased these issues.

SR

I have updated Page 2 of this PDF to expand upon the need for a grooved spindle to ensure adequate oiling. I didn't want Page 2 taken alone to mislead anyone to thinking that the correct placement of the washers alone would provide adequate oil to the top end parts.
Mike

Hi
I have a 1968 Bonneville with rapid wear of the valve tips and the creation of a brown paste on the valve tip and adjusters.
I’ve fitted the spiral machined rocker shafts and used wire to restrict the return hole in the oil tank. This hasn’t cured the problem.

So I’m interested in your(Sonnehaerdt) solution using a non-return valve.
However the thread was 10 years ago.
I just wondered how the upgrade has performed in the last 10 years?
Also is there any chance of photos or a diagram of the upgrade?
I’m no engineer so would find it difficult without more instructions.
Regards
Lemmy

What oil do you use?
Do you have an oil filter?
How do you drive? Short, slow trips?
My 68 has no such problems.

I use sae 40 monograde oil.
No oil filter fitted.
I don’t drive super fast but still had the problem after a couple of long runs, one being 200 miles.

Don't know about over there but we have oil made just for 4 stroke motorcycles.
https://www.walmart.com/ip/Valvoline-20W50-4-Stroke-Motorcycle-Oil/16879750

https://www.valvoline.com/en/4-stroke-motorcycle-oil/
That brown goo could be coming from the clutch.