Seagull slow running

[Frank mellin]

Purchased a 40 plus engine and decided to replace carb jet to allow 25/1 fuel mix.
Put back together, but after using priming button fuel poured out from the overflow hole in side of bowl.
Is this correct
Ie does holding priming button hold flow open until released and should fuel escape from side of bowl if flooded.
Engine started first pull but revs continued to increase despite throttle lever being closed.
Could only stop by turning off tank tap and waiting for fuel to be exhausted.
Am sure there is a simple explanation only clouded by my stupidity.
Any advice appreciated.

 

[Sandro]

Quote"does holding priming button hold flow open until released and should fuel escape from side of bowl if flooded."
Yes.
To stop immediately just shut air intake with a hand.
Don't know about running away. Ask S.O.S. Saving Old Seagulls. very nice people.

 

[neil_s]

My 40 plus only needs a couple of seconds press on the priming button to start from cold.

 

[jwilson]

Yes: priming button deliberately overflows carb bowl, nice rainbow oily stain on sea. That plus choke should give first pull start even on a frosty day. The throttle cable should be adjusted till lowest lever setting actually stops engine. You are dealing with 1940s technology, but the engine itself is very, very simple and reliable.

 

[QBhoy]

Yeah. As said. Normal to come out the overflow when priming. Particularly interested in this post, having just acquired a 40 plus from 1974. Got her running after lying dormant for nearly 20 years. I’ve heard about the conversion to 25-1 just recently there…
So did you change just the jet or did you change for another more modern carb altogether? I’d imagine after changing the jet to suit…you’d likely need to carry out some adjustments thereafter.

 

[VicS]

Yeah. As said. Normal to come out the overflow when priming. Particularly interested in this post, having just acquired a 40 plus from 1974. Got her running after lying dormant for nearly 20 years. I’ve heard about the conversion to 25-1 just recently there…
So did you change just the jet or did you change for another more modern carb altogether? I’d imagine after changing the jet to suit…you’d likely need to carry out some adjustments thereafter.

I s just the needle that you have to change. #8 in this diagram
http://www.saving-old-seagulls.co.uk/images/Villiers carb.jpg

After I changed the needle in my 40 Featherweight I found that I had to screw the mixture adjustment down by nearly 3 turns from flush with the top of the piston to lean out the mixture sufficiently to stop it "4 stroking". I have changed the needle in my 40 Plus too but I have not used it since so I don't know if that will require the same amount of adjustment.

Go to the Saving Old Seagulls website for all the information you are likely to need on running a Seagull.
Saving Old Seagulls: Free British Seagull information, Engine serial number identifier,advice, forum and spare parts.

 

[Leighb]

We had a 40 plus for many years. Getting the throttle adjustment just right took a little experimenting, but once it was correct you could control the speed by raising and lower the tiller arm.
The trickiest thing was judging when to close off the fuel tap when approaching your destination, having no stop button, you had to either turn off the fuel or grab the flywheel to stall it.
I did the 25:1 conversion soon after acquiring it, still rather oily but better than the messy 10:1, and much less smoke.

 

[neil_s]

You can run on less oil just by screwing in the needle adjusting screw. If you're lucky, you can run on 20:1 without buying a new needle. You need to be aware that older Seagull models had smaller main bearings, so they are less tolerant of lean petrol. Saying that, my 40 plus from 1956 is happy on 20:1.