Ducati 250 mk3 piston id

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Scottish888
Posts: 266
Joined: Wed Feb 07, 2018 1:47 am
Location: Edinburgh, Scotland UK

Ducati 250 mk3 piston id

Postby Scottish888 » Tue Oct 16, 2018 10:21 am

Hi,
Ducati piston.jpg

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.
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Eldert
Posts: 771
Joined: Sun Nov 01, 2009 3:23 pm
Location: Hazerswoude Rijndijk Netherlands

Re: Ducati 250 mk3 piston id

Postby Eldert » Tue Oct 16, 2018 3:42 pm

looks like the std 74 mm piston to me

Eldert

Scottish888
Posts: 266
Joined: Wed Feb 07, 2018 1:47 am
Location: Edinburgh, Scotland UK

Re: Ducati 250 mk3 piston id

Postby Scottish888 » Wed Oct 17, 2018 10:35 am

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

ducwiz
Posts: 604
Joined: Tue May 22, 2012 12:52 pm
Location: near Frankfurt, Germany

Re: Ducati 250 mk3 piston id

Postby ducwiz » Wed Oct 17, 2018 4:39 pm

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

Scottish888
Posts: 266
Joined: Wed Feb 07, 2018 1:47 am
Location: Edinburgh, Scotland UK

Re: Ducati 250 mk3 piston id

Postby Scottish888 » Fri Oct 26, 2018 3:08 pm

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,

Eldert
Posts: 771
Joined: Sun Nov 01, 2009 3:23 pm
Location: Hazerswoude Rijndijk Netherlands

Re: Ducati 250 mk3 piston id

Postby Eldert » Fri Oct 26, 2018 6:55 pm

this is what A , b or C means
A , Band C

Eldert

001.jpg
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Scottish888
Posts: 266
Joined: Wed Feb 07, 2018 1:47 am
Location: Edinburgh, Scotland UK

Re: Ducati 250 mk3 piston id

Postby Scottish888 » Mon Oct 29, 2018 1:10 pm

Thank you Eldert


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