What mixture?

[chriswarsash]

Hi everybody, first post so pleae excuse me if not in the right place, etc.

I have a 1973 40+ which will be used as a "get me home" motor on a 13 foot Dory and as a "pottering about" motor on a small inflatable, presumably both uses will be mainly at full throttle.

So, should I keep it as a 10:1 original mix or replace the needle to allow a 25:1 mix?

I'd rather not have the "blue haze" following me around the (salt water) river but am more interested in keeping the old motor going forever!

Thanks in advance for your answers.

[Oyster 49]

Welcome to the forum
A 1973 engine would have left the factory as 10:1 but it should be able to run at 25:1 quite happily. As a compromise I'd suggest going for a 16:1 mix on a standard needle and use the adjustment screw to weaken the mixture a tad to compensate for less oil (and thus more fuel) in the mix.

See how that goes, and of course you could go the whole hog and convert to a 25:1 needle.

Let's us know how you get on.

[headdownarseup]

Welcome aboard

For the sake of "keeping your engine going forever" have you tried using a good quality modern semi-synthetic 2stroke oil instead of going down the "must convert to 25:1" route.
This has to be one of my biggest pet hates of late, and dare i say it, seems to be slightly overlooked. Sorry if i'm going over old ground again for some of you, but you need to consider why your engine was originally designed to run at 10:1 in the first place. It's lasted this long in its current configuration, why start messing with it now! Less oil content in the fuel isn't always a good way to go with worn or very worn crankshaft bushes on top of a suspect maintenance history in little engines like these. They need that oil for a number of different reasons.These are old fashioned engines with an old fashioned technology behind them. Cutting back on the oil in my view is not a wise thing to be doing to one of these older seagulls.
True, with some fiddling you can improve a little bit on how much smoke comes out of the exhaust, BUT there's an awful lot of very good oils out there with low ash/clean burn properties which almost does away with the need for fiddling with needles and jets. Try it before you start fiddling... you might be pleasantly surprised.

All of my old flock (by old i mean made before 1978) run at the manufacturer's intended fuel mix of 10:1, a few even at 8:1 and truth be known they're not THAT smokey at all. If anything quite the opposite which might surprise some of you, and that's largely down to using a good quality semi-synthetic 2stroke oil. Ideally if its biodegradable as well it's a win win situation.

Not a rant, just a few words of caution before you end up doing some irreversible damage to your little gem.

Let us know how you get on. (we don't bite really )

Jon

[seagull101]

I also run most of my flock on 10:1 and my SD on 8:1 and the ED on 25:1, the 416 carbs wont run on 10:1 but i think i will start running it on 20:1.

Jacob

[Charles uk]

A 10:1 mix using a Amal 416 should be OK with a 100 jet

[seagull101]

Thats if i can find a 100 jet! Are they available?

[Charles uk]

Try John Williams first, then British Seagull then mail me, sure I've got some, but I really only supply sexy bits to racers.

If you'd asked 2 months ago I sold my last complete set of 16, from 85 to 160 to a Bermudian racer.

Try John & then BS we need to keep them both profitable.

[JERSEYMAN]

but I really only supply sexy bits to racers.

[tambikeboy]

[Oyster 49]

Yes Charles definitely supplied those bits

[headdownarseup]

I think this is more down Charles's avenue.

EXTREME doesn't come close
https://www.youtube.com/watch?v=fwO35ybyzNg

or this perhaps?

https://www.youtube.com/watch?v=9DKvpgaf9wQ

much sexier (and a lot more dangerous) than racing old seagulls


So, what mixture do you think they're running in these bad boys then

Jon

[Nudge]

So, what mixture do you think they're running in these bad boys then

To start with those motors are 4 stroke!

nitrous for the sprint boat!
and high octaine for the jet boat!!

[Grumpy]

Reminds me of an event a few years back.
Perusing the new stock in a West Auckland mower shop when a largish man, seemingly a commercial operator by his mode of transport, comes charging in, plonks a newish cheap weedeater onto the counter.( 25-1 mixture type)
" I bought this here a few months back and now its kaput"
The shopkeeper calmly asked him what fuel mix he used.
" 91 petrol"\,
How much 2 stroke oil?
"A good dash of oil"
I nearly cracked up at that wanting to scream at him to shut up although knowing any guarantee was gone by then The machine was seized and I could detect a shallow but obvious sneer on the shopkeepers face. There was talk of sending back to the importer for inspection.
My mind was spinning with all the opinions and info of this site over the years of 8-1. 10-1.16-1. 25-1. 20 grade 30 grade tw3 ,synthetic replacement amal carb jets but above all else at the very least settling on some formula and adhering to it with the total knowledge that without a decent mixture 2 strokes and seagulls go kaput or perform poorly.
Since then I have taken time to quietly enquire from family and friends and even strangers how or what they add to their mowers weedeaters or any 2 stroke engine they own or use.
The manufacturers and retailers of the large array of home gardening tools must gain massively from the abuse of these tools besides the fact that 2 strokes need occasional tune ups to continue operating well.
Anyway my questioning has revealed that most home operators are very approximate with their fuel mixtures and do not fully appreciate the genuine need for accuracy.In some cases absolutely totally ignorant
Think If I come back in another life it will be as a 2 stroke garden tool retailer.

[Collector Inspector]

Welcome to the forum
A 1973 engine would have left the factory as 10:1 but it should be able to run at 25:1 quite happily. As a compromise I'd suggest going for a 16:1 mix on a standard needle and use the adjustment screw to weaken the mixture a tad to compensate for less oil (and thus more fuel) in the mix.

See how that goes, and of course you could go the whole hog and convert to a 25:1 needle.

Let's us know how you get on.

Yes welcome indeed.

Oyster hits the nail on the head as far as I do long term old engines not the least Gulls.

A 16 mix actually does a whole shit load of Old Dears......believe Us. Especially with modern marine fuel mix lubricants now off the shelf.

Make sure ignition and spark spot the dog and away ya go!

BnC

[Charles uk]

PROVIDING THEY ARE IN "AS NEW CONDITION"!