Saving Old Seagulls

Newly registered and first post. Purchased motor recently and now attemting to put into service. Fresh gasoline properly mixed at10:1 have looked at carb which appears clean and functioning and starts easily and runs approximately two minutes then slowly dies. Not out of fuel and vent on tank is open. Possible to restart but dies again. This pattern continued over five or six attempts. Any suggestions much appreciated.

Welcome, a picture or a model number would help as all seagulls are not the same, but for a seagull with a villiers carb, you have to be thorough when cleaning the carb and fuel system, you will find you have two fuel filter, one around the banjo bolt on the side of the carb and one on the fuel tap.
Remove both and clean them.

Keith advice is spot on fuel system needs to be spotless, and all filters checked.

I'd also clean and check the points under the flywheel cover.

If none of that works let us know. It does sound a little like fuel starvation though.

As per most typical seagull carbs they have a choke flap.
Is the choke being left on for too long?

Other than that, cleanliness EVERYWHERE in the fuel system is vital, secondly ignition must also be top notch.

Apart from that, go through everything systematically. Spark. Fueling. Compression.

One thing at a time and you'll get there.

Pics and engine serial numbers help us a lot too. Show us what you've got and we might be able to shed some more light.

Jon

Thanks for suggestions and comments and encouragement.
I agree that it sounds like fuel starvation but as the motor was dying I tickled the carb which produced overflow of fuel which suggests to me that carb levels were adequate. Should also say that steady stream of cooling water flowed from head while running so not thinking that it is overheating issue. Is it possible that it is air/fuel mixture adjustment in the carb that affects performance as motor heats up?

Expect be back at motor on Monday at which time will note serial# and take some fotos and of course check compression and look at points and let you know results

Just for laughs,spray some WD40 or like around the crankcase area while it's running,if it picks up,loss of vacuum is one of you problems

I had a silver century that had a hairline crack from the transfer port to the cylinder wall. Ran ok while cool but after a few minutes it died. Same as yours. It wasn't until l replaced the cylinder block that l found the crack, hardly discenable . Hopefully that is not the case with yours.

Thanks for suggesting other test and possible cause. Plan to make further efforts with motor tomorrow and let you know what I find.

I had a silver century that had a hairline crack from the transfer port to the cylinder wall. Ran ok while cool but after a few minutes it died. Same as yours. It wasn't until l replaced the cylinder block that l found the crack, hardly discenable . Hopefully that is not the case with yours.

I wonder if that is the problem I have with one of mine. It will start up fine run well for 5~ 10 min. then revs will drop for a bit then pick back up.
It will keep doing this... I have run it for over an hour like that (had to to get home again).

Might have to pull it down and have a good look!

Thanks

Might be a good idea to heat up the block with a blowtorch and look for the tell tale sign a small weep from the inside out worked for me china...

Thanks for further comments. Did not have a chance to look at 40 plus as am trying to get my vintage Chrysler ob going.GGGrrrrr.attached are fotos of 40plus and both motors mounted on 1972 Chrysler Charger.
Determined to leave the dock with one sound motor before summer ends

Nice motor!

Interesting tank, normally you see the very early ones with no indentations at all or you see the overly common one with SEAGULL indented in the side!

Or maybe i have just not seen one before.
I'm sure somebody will put me righ!

Jacob

Thanks Jacob. Took the motor home and decided to check compression which was approximately 80psi and in process realized that sparkplug had not been properly tightened. Then checked spark which seemed good. Then put all back together and ran motor in water tub and ran well..... so plan is to take it out to boat in few days and try again.

Following on prior post. Yesterday motor ran great in tank without issues however I had propellor off so that water pump would force cooling through engine. Today replaced prop and took to boat and under load no different than prior results, ie died after approximately three minutes. What particular motor issue would only show up under load?
Thanks in advance

You might also have a leak from the head gasket that only shows itself as the engine warms up. It might be worth removing the head gasket, and giving everything a clean and a good inspection. You can also clean out the waterways in the block at the same time.