As I have had a couple of inquiry's regarding throttle stops on S25 carbs here is an article I wrote for Leading Link back in 2023.
One of the problems with the S25 carb fitted to many Greeves trials & road bikes it that the type fitted did not have a throttle stop screw fitted. Villiers did make an S25 with the screw, the S25/7 & /8, which was fitted to minicar engines such as Bond. Whilst a throttle stop on a comp bike is not an issue, not so on a roadster where a reliable tick over is required.
Luckily Villiers did make provision on most S25 carb bodies for the throttle stop screw in the casting, it was just not drilled through and tapped. So all you need to do is drill out the hole with a 4mm drill and tap it 2BA. The screw itself is a 2BA slotted head screw 15mm long with a 90 degree pointed end. A small 10mm long compression spring needs to be fitted under the screw. If you cant find a suitable screw & spring, Villiers Services (01384 265797) should be able to supply them, part number V1948E (screw) and V749E (spring)
One of the problems with the S25 carb fitted to many Greeves trials & road bikes it that the type fitted did not have a throttle stop screw fitted. Villiers did make an S25 with the screw, the S25/7 & /8, which was fitted to minicar engines such as Bond. Whilst a throttle stop on a comp bike is not an issue, not so on a roadster where a reliable tick over is required.
Luckily Villiers did make provision on most S25 carb bodies for the throttle stop screw in the casting, it was just not drilled through and tapped. So all you need to do is drill out the hole with a 4mm drill and tap it 2BA. The screw itself is a 2BA slotted head screw 15mm long with a 90 degree pointed end. A small 10mm long compression spring needs to be fitted under the screw. If you cant find a suitable screw & spring, Villiers Services (01384 265797) should be able to supply them, part number V1948E (screw) and V749E (spring)
Attached Files
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