Author Topic: 2-stroke oil for a 2 3/4 hp?  (Read 367 times)

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Offline Tim OConnor

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2-stroke oil for a 2 3/4 hp?
« on: 12 Sep 2022 at 01:12 »
I read where one person said he was using quality 2-stroke oil for his 2-3/4.

Good idea ? Bad idea?

Seems to make sense but I don't want to risk my precious engine.

1920 2 3/4 W-20

Offline cardan

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Re: 2-stroke oil for a 2 3/4 hp?
« Reply #1 on: 12 Sep 2022 at 10:26 »
I did it for a while.

Two stroke oil seems like a good idea for a vintage four-stroke total-loss engine, where a decent amount of oil ends up passing the rings and being burned. Two stroke oils are "low ash" so should stop build up of crud in the combustion chamber. And I'm sure they would do a good job of lubricating bushes and bearings.

However the big downside is that the oils are usually rather thin and very "slippery". While using two-stroke oil (Valvoline Racing Two Stroke was the brew of choice) I had leaks everywhere, mostly around the hand pump and drip feed. Oil everywhere.

My choice would be straight low-additive mineral oil. I use on of the Penrite products: I think Shelsey Heavy (or whichever is a straight 50). If you're in cold climate the 50 gets very stiff, and a 40 or even 30 would be OK.

If you're just doing some local pottering on a 2 3/4, I'm sure the engine would tolerate any modern engine oil, despite what might be said out there. Better any oil in the oil, than some fancy oil in the tank but forgetting to put it in the motor while you're riding.


Offline Hamwic

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Re: 2-stroke oil for a 2 3/4 hp?
« Reply #2 on: 12 Sep 2022 at 10:54 »
Apropos of two stroke oil - Riders of veterans and other bikes with exposed valve gear like to use a drop of two stroke oil added to the petrol. This is to lubricate the inlet valve stem(s), which gets no other form of lubrication. When side valve springs are enclosed, a puff of oily smoke from the exhaust guide is sucked up the inlet guide, but when the valve springs and guides are exposed, the dry inlet guide gets no oil, and with wear acts as an air leak, so a bit of oil here via the incoming fuel charge is good. My M32 has felt hats between the valve spring and the stem, and the application of the oil can is called for now and then to keep things sweet. Whether or not these are original or not I don't know, but it was a common modification to try to keep grit out, and oil the valve stems at the same time.

Cheers for now

Offline graeme

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Re: 2-stroke oil for a 2 3/4 hp?
« Reply #3 on: 13 Sep 2022 at 08:52 »
I also had a similar experience in trying 2 stroke oil in a veteran - it leaked out everywhere, down every thread in the pipework etc. I have used 20/50 oil to good effect.

Cheers, Graeme