Saving Old Seagulls

My recently acquired '75 WSPCL had a "modified" choke plate (solid plastic - no hole). A full choke position allowed for a relatively easy start but continued operation required keeping it in a very slightly opened position or else it would stall. After replacing the choke plate with an original-like version (with hole) I have considerable difficulity starting. I have a 25:1 kit on order but am currently running 10:1 mix. It seems this Silver Century Plus requires excessive fuel to air ratio in order to start and continue running. I have not yet attempted to adjust carb. Any thoughts or suggestions? Thanks.

there are no adjustments on the amal carb, it could need a good clean out as the motors normally are easy starters

Give the carb a very good clean including the 2 jets

Thorough cleaning of tank, float and carb, plus fresh fuel did not improve performance. However, received and installed 25:1 conversion kit, fresh batch of 25:1 fuel and instant improvement. The old jet and new jet looked remarkably alike (old jet scratched and could not read any nomenclature on it). So, it appears to this novice that the real cause of improvement was not a new jet but rather 25:1 fuel. I suspect that the old jet was actually a 25:1 version and objected to a 10:1 fuel mix. In addition to full range of choke and throttle control, other benefits include a much smoother operation, less smoke and near elimination of gull droppings. Has anyone else had a similar experience? Your thoughts appreciated. Thanks.

I use the right size nylon fishing line and push that through the jets...never anything metallic which could damage the jet passages. I learned that on this forum which probably saved me a lot of hassle regarding carburettor fuel flow.
I also shoot a few puffs of air through the whole system with my air compressor.
I would also add that pouring a little fuel stabilizer in the tank and running it through the engine helps prevent stale fuel which often is the cause of jet blockage. (When the motor is rarely used).
Keeping good stabilized fuel in the tank also keeps the cork stopper wet inside the fuel petcock valve.

David
Ottawa Canada

hi, i a bit new to these motors what exactly is fuel stabaliser ?

Basic chemical composition: BHT - Bytelated HydroxyToluene

It's sold in automotive maintenance stores everywhere and is called fuel stabilizer, and as the name says it acts on the properties of stored gasoline to sustain its freshness for up over a year depending on the brand.

If you don't use this product, you run the risk of having your fuel turn bad into a sludgy varnish that more or less decomposes and looses its explosive properties. This is very important because the engine (the British Seagull or any engine) is engineered to combust fresh gasoline which will give the necessary pressures to run it properly.
Decomposed fuel will eventually clog the whole fuel system...from tank petcock right through to the carburettor jets (small orifices that let in just the right amount of gas that mixes with air to permit the right explosion triggered by the spark plug). You probably know all this already. Bad fuel also smells like hell.

Todays fuels turn bad faster because of all the additives, and when you add to that the fact that the high quantity of 2-cycle oil mix used in Seagulls (10:1 or 25:1 depending), you have the perfect storm for fuel system-related engine problems.
I believe the host of this site, John Williams, has a chapter on this in the Q&A section.

Using fuel stabilizer in all internal combustion engines insures perfect performance when the right season arrives and is quite cheap to purchase. Pour the right amount for the quantity of FRESH fuel in the tank, start the engine, and let it run a good 5 minutes...to make sure the stabilizer passes through the whole fuel system.
For example, all my neighbors have spent a bundle on engine carburettor repairs for their snowblowers where we live, and I've had mine for 21 years now and never even went to the service shop for anything except a new spark plug.

Hope this helps.

David
Ottawa Canada

An example of the product sold here in Canada...

david1230 wrote: (small orifices that let in just the right amount of gas that mixes with air to permit the right explosion triggered by the spark plug).

I've been led to understand that it is more of a progressive burn than an explosion but I could be wrong...

You're quite right Hugz...just like the internal progressive burning of nitro-cellulose gunpowder inside a cartridge.
The process happens in micro-seconds...fast as hell...and you don't have time to explain this to the guy receiving the bullet, and after he's hit it ain't worth it anymore!

Cheers!

hi david. i bought a 1977 silver century in june, i saw it running in barrell for about 3 mins. it ran ok but he said it had not been run for years, he put fresh petrol in after agood few pulls it ran, so fuel is now 5 months old. if i drain tank and add fuel stabilizer run for 5 mins could i leave some in tank for winter or run it all out. ps. bet your neighbours whish they knew about this product. cheers