As per the title, does anyone know a supplier of what Yamaha call the "valve" that sits inside the tap for the 1973/4 MX250/360 petrol tank? Yamaha don't list it as a separate part, but it could easily be a part that is shared with other models and makes.

The tap is genuine Yamaha.

Approximate dimensions (because I think mine has shrunk and the tap is leaking!) are diameter of 22mm and thickness of 2.75mm. There are four inner holes of perhaps 5.25mm, with NO hole in the centre.

Many thanks.

I follow this thread with interest because the petcock is seeping fuel in the OFF position on my 1974 MX250A.

It is not leaking like dripping on the floor. But if you pull the fuel hose off the carb you will see that it will slowly seep fuel when it is in the OFF position.

Schu.

I've taken a punt and ordered one of these - I'll post here how it goes.

Genuine Suzuki Petcock Seal / Fuel Tap Gasket For TS100-TS125-TS185-TS250-TS400 | eBay UK

Part arrived and I fitted it this morning and so far, so good.

The part supplied was in a sealed bag with a Suzuki label and was number 44341-28071.

I thought the mx250/360 had this type below so won't have reserve involved.
All good though if sorted.

www.partzilla.com/product/yamaha/322-245...ac9849250d6d2c16b81e

It does, but still uses the style of valve/gasket shown.

My tap was NOS and leaked from new, so I'm guessing that the original valve had deteriorated with its many years in storage.