Saving Old Seagulls

newby here so sorry if this has been asked before but done a search and cant find the answer.

i have just acquired a Silver Century/90/Osprey and im having trouble keeping it going it runs for about 5 min with a lot of smoke then dies. i was told by previous owner who had not had it long it was a 10-1 mix which i am using. also after it has cut out wont start unless i take plug out and wiipe it down put it in and fires up again for similar time with lots of smoke
ive been looking at videos on the web of them running and they are not smoking as much as mine, which is that bad at times you cant see water in the tub even the engine occasionally have read a few similar problems on here and cleaned it all down fresh fuel and its still the same.
i have also watched a video for changing jets and on there it says there 40 for 10-1 and 45 for a 25-1 mix now this is the bit where im lost my jet has 25 on it so does that mean i should be running it at 25-1 as this would cut the smoke and and reduce the oil residue being left on the water barrel im using

thanks in advance as any help advice would be much appreciated.

Your serial number will help to identify exactly which model your talking about.

the serial number is WSPC1810D1 says its made april 1971 and is a 5hp Silver Century/90/Osprey

its the jet that i have in carn with 25 thats making me wander if its the mix ratio as ive read it should say 40 or 45

thanks

Hi, you’ve got a silver century.

ive been looking at videos on the web of them running and they are not smoking as much as mine, which is that bad at times you cant see water in the tub even the engine occasionally have read a few similar problems on here and cleaned it all down fresh fuel and its still the same.
i have also watched a video for changing jets and on there it says there 40 for 10-1 and 45 for a 25-1 mix now this is the bit where im lost my jet has 25 on it so does that mean i should be running it at 25-1 as this would cut the smoke and and reduce the oil residue being left on the water barrel im using

You have as never-outbored says a Silver Century, which should have an Amal twin jet 46N carb which has as the name suggests 2 jets.

The jet you've given us the size from, was the economy jet & they are all size 25, the important one that we want the number of & corresponds with the fuel mix, is the power jet & comes in 3 sizes, 40 for 25:1 mix, 45 for 10:1 mix, or 50 for 10:1 in cold climate areas.

ok thanks
there are no other numbers on that jet and none on the longer one either

so will give it a try at 25-1 as 10-1 is just bogging engine down smoking like a cauldron and leaving a lot of oily discharge in my tub

A 25:1 main jet has the smallest size hole of all the jets, as the fuel with the least oil content has a lower viscosity decreasing the oil content of your fuel mix will make your current jet pass more fuel, is that what your trying to achieve?

Remember your Seagull is close to it's 50 birthday & you don't know how hard it's life has been, do you want to limit it's lubrication?

You must know someone with a similar Seagull living locally, why not borrow a power jet from them for 10 minutes, refuel with the mix that suits that jet & give it a try, it will let you know if your jet has been messed with!

no im trying to cut the smoke down which i think is eventually killing engine as it wont run for more than 5 min and when i put it in drive that makes it smoke more ,also all the oil residua its leaving in the water tub had a similar problem with a jet ski once and that was down to mix being to rich.

as for someone near me having on to be honest its very doubtful as never seen one around here before. most the boaters round here look down on my little put put boat and are there all outsiders with there big ribs and super yachts .

unless there is someone near caernarfon on here that has one i could try

Between 1937 & 1994 circa 1,000,000 Seagulls were produced, allowing for the ones that were exported, would leave you with around 1 Seagull produced for every 100 members of our population!

Have a walk around your local boatyard & ask all the staff how many Seagulls they have in their sheds?

Then put a wanted add in the local newsagents.

thevanwizard wrote: ↑Sat Oct 10, 2020 2:05 pm it wont run for more than 5 min and when i put it in drive that makes it smoke more

I would strip the motor, if it wont run for more than 5 mins. or at least do a compression test.
Are you getting water out of the outlet when running? if not it could be stopping due to a partial seize.

In the FAQ section there is mention of similar symptoms relating to leaking head gasket or cracked block. There is no specific mention of excessive smoke, but might be relevant.

Cheers, Mark