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Hi,

Can anyone tell me what these numbers stamped on top of the piston mean?

784 -65075/3

Bike is a Ducati 250 mk3 1974.
The previous owner said he had never carried out any work on the bike, no idea about the first owner, mileage is under 7000, I think the previous owner never bothered to check the oil level as it had a minimum amount.

looks like the std 74 mm piston to me

Eldert

Thanks Eldert,

The engine has very little compression yet the bore and piston did not look so bad when I removed the cylinder, no significant wear ridges, rings were free I am hoping a piston clean up and a fresh set of rings could make a difference.

Regards

Have you checked valves and seats ? And have you measured your piston and cylinder bore diameters?

Hi Ducwiz,

I did not check the bore yet, just a quick visual but no wear ridges near the top.
I poured fuel inside the head combustion chamber and it held with only a little dampness around one of the valves, so not too bad there.
Will measure piston/bore accurately when I do the crank.
About the piston numbers, they don't match any given in the Haynes manual. I am assuming like Elders says that it is the original piston but maybe not.
It looks like it is a B grade piston as there is a B stamped on it, will need to measure it with calipers.
Any idea what the A or B grade means?

Regards,

this is what A , b or C means

Thank you Eldert