Two stroke oils again

[Trevethan]

OK The aged Evinrude is almost out of petrol and I have no 2 stroke oil left, The bit that came with the boat is all used up and I cleverly threw the bottle away without noting the type/brand

There was a thread a while back about 2 stroke oils for bike and their lack of suitability in water cooled engines.

Then people started to get all misty eyed over some old castrol stuff and the smell and so so on, but nothing ever got resolves as I recall.... So please what oil and what ratio should I put in a aprx 30 year 9.5 HP evinrude... which is now working on 2 cylinders,,, well most of the times after some fettlng in with a small hammer... Still drops to one at low revs which makes me think (well I have been told) the crankcase seal is a bit dodgy.

I'll see what it does after I put another couple of clean tankfuls through as the loss of the bottom cylinder is occuring at ilower and lower revs now I have stopped using the (probably very old) fuel the previous owner supplied...

Cheers,

Nick

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[Dave_Snelson]

Down to the chandlers and buy a good make - like Quicksilver 2-cycle outboard oil. Your ratio is 50:1.

Don't use other types - it ain't worth it.

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[Trevethan]

Thanks!

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[andyball]

...lack of suitability in water cooled engines...


This is often mentioned, as if all ( or even most, these days) motorcycle 2-strokes are air cooled, which they're not, of course. Think Scott made water cooled 2-strokes from 1910 onwards.

Whether or not the raw water cooling of outboards means that the cylinder reaches a lower temp. than normal , I'm not sure. Given that temp is fairly crucial for good performance of 2-strokes it's possible that they're designed to reach an optimium temp. despite well cold water.....of course most people just buy the marine branded stuff rather than worry about it.






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[Trevethan]

Tis just the nearest chandelry is miles away and there is a bike shop around the corner......

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[andyball]

I've used bike oil in 2-stroke outboards w/o problems, there was a bottle in the shed already!.

I've not ever heard of any actual difficulties- mostly just oil company "specially formulated for the xxx conditions found in xxx engines" labels & the usual stuff about outboards running very cold so need marine oil.



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[Duncan_Hamble]

The oil you use for an outboard should be to TCW3 standard. The W stands for water cooled. Most outboards, especially older / smaller ones will run much colder than a modern motorcycle.

Having said that, I did run my old 20hp Yamaha on motorcycle oil when I was a student. However, I ran it on 50:1 instead of the recommended 100:1. I never trusted that 100:1 was enough oil.

Now I have to use expensive DFI oil for my Optimax £23 for 4 litres :-(

Duncan

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[muchy_]

The only real difference is that the marine stuff is water soluable after its burnt and the bike stuff isn't.
If you use the bike stuff you will leave a nice oil slick on top of the water behind you, which may get you in trouble on inland waters.

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[sailorman]

i have just bought a Tohatsu 3.5 it runs on 50 - 1
the Mariner 3.5 ( same engine ) 100-1
why ??.

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[andy_wilson]

Liquid cooled motorcycles

are nearly all 4 strokes.

2 strokes are all tiddly little scooters and 125s aren't they?

Even in the good old days the 250s and 350s were air cooled, Kawasazi had a triple that always cooked the middle pot.

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[andyball]

Re: Liquid cooled motorcycles

"liquid cooled motorcycles are nearly all 4 strokes"

Err, no they're not....or weren't when I stopped fixing bikes in early 90's


Ignoring Scott from 1910+

Suzuki did a 750 triple in the 70's ( 2 str. water cooled)

Yamaha did watercooled 2-strokes (road bikes) RD 250/350LC in the 80's extending to 125's & 80's....Honda, suzuki & kawasaki all made w/cooled 2-strokes too....Suzuki did a 500cc square four (RG500)

Most all mx/enduro 2-strokes were w/cooled from (guessing a bit) late 70's.

For some years, if it was watercooled & not a Goldwing, it was likely a 2-stroke.


Certainly less 125+ 2-strokes now though- blame the Americans & emission laws...but fuel-injected & direct-injection 2-strokes are creeping back.


& yes, The KH's did often seize the middle cylinder.

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