Leanest mix?

[pat777]

I always thought the leanest mix for running Seagulls was 25:1, there are a couple of people advertising seagulls for sale on a website over here, saying that the mix is 50:1. I guess they just don't know the correct mix or have others had success running a leaner mix?

These are quotes from responses to prospective purchasers asking about what mix is required.

"it used to be 10/1 when there was leaded petrol but now its 50/1 with unleaded"

"standard shaft /short 50/1 mix"

Any thoughts on the subject?

[Hugz]

From FAQ main site:

http://www.saving-old-seagulls.co.uk/faq/faq.htm

"My motor says I can run it on 50:1, is that right?

Yes, and No. Late, 1990 models were sold with the fuel mix quoted as 50:1. Subsequent testing proved that this was ill advised and I would not recommend less than 25:1, with good outboard oil, whatever the model. They self destructed!"

[pat777]

Thanks Hugz,

I've been to the faq page many times before, just curious whether anyone has experimented with a leaner mix. I guess it would be ill advised.

Cheers Pat

[pat777]

So moving swiftly on...

A bit of a novice question here, but what exactly is the oil in the mix actually lubricating and what exactly is it that fails when not enough oil is put in the mix.

Also why are other two stroke outboards like old Honda's or Yamaha's able to run on a much leaner mix. I can see they look very different on the outside but I guess there is something very much different going on beneath the surface too.

Thanks Pat

[Keith.P]

90% of seagulls have bronze crank bushes, the oil lubricates them, among other parts, without the oil it will seize.
Without lubrication the bushes would burn up and wear out, which would allow air to leak in and out and with no crank pressure, the fuel would not be drawn in from the carburettor.
Two stroke oil is pretty modern stuff, it wasn't around when some of the old seagulls were new.

[Oyster 49]

The more modern engines tend to have needle roller big end bearings also, which can run on a lighter oil mix.

[pat777]

Thanks guys, that's some helpful information. This clip might be of interest to other newbies, to see where the bronze crank bushes are.

[pat777]

Some more interesting reading from the main site.

http://www.saving-old-seagulls.co.uk/i_ ... ll/5_r.htm

[Keith.P]

Wasn't the 5R, just a 170 fitted to a Yamaha leg?

[Oyster 49]

It was a modified kingfisher fitted to a Yamaha leg. I've just re-read this article on the SOS site.

http://www.saving-old-seagulls.co.uk/i_ ... ll/5_r.htm

[headdownarseup]

I've often wondered why some people seem to think that by leaning the oil content in their fuel/oil mix will yield any gains.
Is it that some folks think that by running at 25:1 compared to the older 10:1 setting that the levels of smoke will be less? In some cases yes, but let's not forget that 2 stroke oil (like all other types of oils these days) has evolved into something that it never was 30 or 40 years ago.

In recent years there seems to be quite a shift towards cleaner running with less emissions being dumped into water courses or into atmosphere. Fantastic in some respects, but bad in others as not everything is capable of such stringent restrictions.
We've seen a lot of this within the car industry of late. Modern cars are very different to a typical seagull we like to tinker with. Myself as a time served mechanic would frown at trying to tinker too much with a seagull's oiling requirements. The seagull designers obviously knew what they were doing back in the day with the technology available at that time. Nowadays it seems there's a lot of folk wanting to lean out their fuel/oil mixture too far that the dear old seagull wouldn't be comfortable with, and subsequently the end result could be irreversible damage. These are old and in some cases quite fragile engines that deserve looking after if they're going to last for another 50 odd years. Don't skimp on the oil.
Any seagull will produce a bit of smoke, so what, it's what they ALL do. Reducing the amount of OIL that's mixed with the fuel is sometimes a very bad thing to do with some of these older designed engines. They are what they are.
I can quite happily live with some smog in the air or a small oil slick on the water. They're not as bad as some people seem to think they are.

As with anything old, look after it. Once it's gone, it's gone for good.

Jon

[seagull101]

I run all my seagulls on 10:1 except my amal 416 EDL. The smaller engines hardly smoke but the larger ones smoke running on 10:1.
In the past 2 years, running a large variety of seagulls, a mariner and a Suzuki i have only used a 1 gallon bottle of 2 stroke oil.
In my opinion that is enough proof that its not really worth converting to 25:1 to save on oil!

Jacob

[headdownarseup]

My point exactly Jacob.

For most of us that use our seagulls perhaps a handful of times over the year, the total amount of oil that gets used is going to be negligible.
(if i'm being totally honest, most of my un-used premix fuel gets put to use as a parts wash for de-greasing etc.)
Even at 25:1 the savings are not that noticeable.
The smoke levels on the other hand are sometimes drastically reduced.

I've always used a good quality biodegradable semi-synthetic 2 stroke oil specifically designed for use in outboard engines. All of my seagulls seem to be doing just fine on it and most of them don't really smoke that badly at all.

Jon

[mark1305]

I run all my seagulls on 10:1 except my amal 416 EDL. The smaller engines hardly smoke but the larger ones smoke running on 10:1.
In the past 2 years, running a large variety of seagulls, a mariner and a Suzuki i have only used a 1 gallon bottle of 2 stroke oil.
In my opinion that is enough proof that its not really worth converting to 25:1 to save on oil!

Jacob

Interesting point. As I am new to Seagulls with my recently acquired Forty Plus, I'm old enough to have been around outboards and other small two cycle engines here in the U.S. as they progressed from 16:1 to 24:1 to 25:1 to 50:1 and eventually to variable ratio oiling (VRO) that can lean out to about 100:1 under no load conditions or go 50:1 or richer under hard load conditions.

In my case I ordered some parts from John here at S.O.S. to refurbish the fuel tap and fit the Villiers 25:1 needle before firing the motor up. I am not looking to save on oil by switching to 25:1 mix but rather reduce smoke and oily messes from occasional drips/leaks. Before mixing the first batch of gas at 25:1 this past weekend and firing the motor up for my first time I thought seriously about going 16:1 with the needle conversion already done. The motor is in great shape and I want to keep it so and actually use it on the water. I rationalized that would be a good compromise between 10:1 and 25:1. But in the end I went all in at 25:1.

I was amazed and pleased at how little smoke the motor made. And I run good quality TC-3 oil in all my two stroke lawn maintenance gear, so I know how modern oil produces so little smoke at 50:1. Now I know how clean it burns at 25:1. Thinking more about it, now I may switch to some 16:1 mix to see what difference if any that makes while getting maybe more peace of mind about my motor's health.

[seagull101]

The 40 series motors hardly smoke out at sea, they produce such little smoke that it all blows away instantly!