Atco Royale B24 Tuning Help!
Good afternoon all! I am glad I found you and I'm also happy that I'm now a fully fledged member of the Old Lawnmower Club because I have inherited a rather lovely Atco Royale B24 cylinder mower from my neighbour. It got too heavy for him to use anymore.
It's not been started since 2019 when it was last serviced and so I set about cleaning it all up. Put the carb through my ultrasonic cleaner a couple of times, replaced the spark plug, changed the oil, put a splash of petrol in the cylinder and the rest in the tank.
4 pulls of the starter and she spluttered into life which was a great moment! :)
The only trouble is now, it's running really rough and I'm not convinced all the throttle linkages are installed correctly. I also think the carb needs adjusting... But this is where my (basic) knowledge of engine tuning ends. So I'm wondering if anyone can help shed some light on the attached photos.
This first image shows where the throttle cable meets various linkages, but the grey connector keeps on pinging off to the right of the spring. This doesn't seem right to me!? Should there be some sort of retainer to stop it from moving? Is it in installed in the wrong place?
The second part of my question relates to the carb itself... There are two screws on it... The first is to the side of the carb - near the throttle valve. The second is on the bottom of the metal "bulb" under the carb...
What does each screw do and do they need adjusting?!
If anyone perhaps has a photo of their royale that might help with the linkages at least?
many thanks
Forums
Did you get this resolved? I…
Did you get this resolved? I have similar issues with my B 24. The main screw underneath and in the middle of the bowl for the carburettor is the main mix. The suggestion for tuning this is to fully screw it in but only finger tight taking care not to over time. Then back this off 1.5 turns. Start the mower and whilst it is running you will screw this in by fingers until it starts to splatter, at which stage back it off and count how many turns until it again starts to splatter. The middle point between splatters is about right for the overall mix. The screw on the left as you look at the rear of the carburettor is the idle mix Which it is recommended to repeat the same process
Which it is recommended to repeat the same process
My problem is that I have rebuilt the carburettor and it now runs way too quickly so I have backed everything off now when I use the throttle it goes from ticking over nicely to revving frantically in the Tiniest of touches to the throttle lever.
Tiniest of touches to the throttle lever.
If anybody has any advice on this it would be a great relief
From what you have described…
From what you have described it’s more likely to be a governor / linkage issue than the carburettor itself. Assuming that the governor has not been messed with a couple of images of the throttle and governor linkage may assist with a diagnosis.
An understanding of the principle of governor operation may be useful. The governed speed of the engine is the product of the governor trying to shut the throttle which is opposed by the governor spring tensioned by the throttle lever and cable . Simply when opening the throttle while watching the linkage you should see the link from the governor pulling back against spring. Maintaining a steady speed is continuous balancing act between the governor mechanism and the pull of the throttle cable via the spring.
I can’t help with an image…
I can’t help with an image of a similar machine but what is immediately obvious is that the end of the throttle cable is hooked up on the rim of threaded adjuster instead of sitting down in side it.
You say that you put the carb through your u/s cleaner ; may seem to be a daft question, but you did dismantle it first ?? In fact, in your image it doesn’t look like it’s been through the cleaner at all. Perhaps just a fuzzy image?