choke plunger tip/seal

[RobinSF1]

I have stripped and cleaned my carbs (+petcock filters and rinsed out the tank with paraffin) following some petrol starvation due to muck blocking the filters and some fine sediment in the float bowl.

The end of the 'choke' plungers have a rubber/viton seal which has a doughnut shaped indentation i.e. outer ridge and pip in the middle. Is this how they are meant to be? Whilst I had no obvious carburation problems before my last ride, thought it worth checking if these should be replaced before ordering some other carb bits. I'm assuming they are original 40,000 mile/40 year old parts.

Thanks Robin

[RobinSF1]

To answer my own question, the seal shouldn't be as I described, this will lead to rich running. I had thought I would have to buy complete choke assemblies but replacement tips are available for £7/pair with free postage.

This ebay ad shows before and after pictures. https://www.ebay.co.uk/itm/324178663069 ... MyEALw_wcB

[Steve Brown]

I've bought these and yes they are fine. It is normal for the rubber to take a bit of a 'set' or an imprint but so long as it is still soft enough it will seal. You do find them crumbling and broken sometimes so well worth checking.

[3potjohn]

Not unusual to have choke pistons perish causing an increasingly rich mixture and not just on Dellortos. My Bing slide carbs did exactly this on a 60/7.
John

[Vitesse]

I was told that the answer is to keep the chokes "on" when the bike is not in use. That stops the tips deforming. Makes sense.