I have a 1970 T120. I have learned form reading various comments that "my" engine and primary share the same oil - via small holes between the primary case and the crank case? Does this mean that the primary will be kept automatically at the right level as long as the engine oil tank has enough oil? Do I therefore need to fill/check primary?

I am a bit confused?

Any help much appreciated

Thanks

Mark (UK)

The level is maintained by the three small holes, and the communication of the blowby to the primary case, and out the breather, is accomplished by deleting the seal between the mainbearing and sprocket which was used up through 1969.
Yes, your primary oil is the same as the engine oil, and the level is maintained by the engine operation and should not require any topping up. Checking the level occasionally is not a bad idea, to ensure that the holes have not become clogged.

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Triumph old, Triumph new, any Triumph will do.

DorkingBonny, two things to remember here. Firstly and MOST important, it is better to have LESS oil than too much in the primary case. Secondly, it is better to put straight grade SAE20 oil in the primary and NOT 20/50. The straight 20 WILL NOT CONTAMINATE the engine oil.
However, BOTH of these will benefit the the barely capable standard clutch.
I would drain the oil, remove the cover clean it all out and check the clutch, chain & adjuster and the alternator ready for the start of the season. New gasket and fill to the CORRECT level and ENJOY .
See you and your bike at the Bexley Legend rally in July????
Roy.

Depends on what you mean by "contaminate", dagad. The engine oil will eventually mix with the primary oil.
Better to use 10W30 Royal Purple or even Mobil One synthetic and get the benefits of less viscous properly engineered lubricant which will better serve both the clutch and the engine.

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Triumph old, Triumph new, any Triumph will do.

DO NOT USE MOBIL 1 in the primary, the clutch WILL SLIP and DRAG............ FACT :hammer:
Contamination, if there is any, will be the sae20 being dragged into the engine, not visa-versa. That's why when a crankshaft seal is fitted (camshaft breather type) it is fitted the wrong way around, to stop oil being sucked INTO the engine FROM the primary.
Roy.

If nothing moves out of the crankcase, then why is there a vent at the upper rear of the primary case???
If your clutch both slips and drags, then it is most likely due to the plain plates being buffed smooth and/or the friction plates being glazed. If you are running 10W30 Mobil One or other quality synthetic oil with clutch plates in good shape, you will have NO clutch problems.

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Triumph old, Triumph new, any Triumph will do.

There is no settlement to this age-old (well, since the advent of synthetic anyway) argument/discussion.

I'd say we need to see the requisite links to all the scientific analysis, laboratory tests, long-term road testing, etc.

You say potato, I say macaroni.

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GrandPaulZ
Author of "Old Bikes"
Born Again Bikes
My Photos

Ok Guys two different opinions............ My clutch is dry, does not slip or drag and breaks instantly. I can also start it in gear with the electric start, NOT BRAGGING BUT
Dorkinbonny give it a try, what Mecchanica says and let us know. Proof of the pudding etc. etc.
Oh, did I also mention, the SAINT was built in 1967 with NO VENT in the primary???
Roy.

Right, NONE of the Triumphs vented into the primary until 1970. Not my 63, my 69 Bonnie, my 68 Bonniger (Tigerville). None of em. As far as I'm concerned, it was a bad idea to merge the primary and the engine lubrication systems. In fact, if you have the 70 on, I advise you to go back to the old system.

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Triumph old, Triumph new, any Triumph will do.

Yes my friend, I agree with that.
Roy.