Barn find: 196? Ducati 250 in Massachusetts USA

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Dukati250
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Barn find: 196? Ducati 250 in Massachusetts USA

Post by Dukati250 » Sat Dec 01, 2018 10:06 am

Hello to all,
My name is Vladimir and I live in Massachusetts USA.
Just a couple days ago I took a 600 mile trip to far away place in northern Maine to buy a Ducati 250 barn find.
I was told it is a 1967 Ducati Diana 250 Mk3 and that it was stored in a barn for about 50 years. It seems to be in pretty good shape and mostly complete.
Here are some questions I have as I’m trying to figure out exactly what it is and how to get it running and tuned up:

1)exactly what year is it based on the picture of the indentification plate (see pics)?
2) what is a good number for a compression test on these 250 engines?

Thank you very much
-
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Dukati250
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Re: Barn find: 196? Ducati 250 in Massachusetts USA

Post by Dukati250 » Sat Dec 01, 2018 10:08 am

Some more pics.....
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Craig in France
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Re: Barn find: 196? Ducati 250 in Massachusetts USA

Post by Craig in France » Sun Dec 02, 2018 4:03 am

Hi Vladimir,

Welcome to the Forum and congratulations on your find!

Model
The engine number 97173 confirms what you were told: a 5-speed 250 Mark 3, also called a 'Diana' in the US.

As to date:
1. The production run of the 5-speed 'Type B' 250 Mark 3 went from 1964 to 1967. However the DM250 M3 prefix to the engine number, plus the later style kicker and footpegs, makes your bike a 1966 or 1967.

2. Numbers for 1966-67 went from 92172 to 104500. However, Ian Falloon has a photo* of what is identified as a 1966 bike with an engine number which, at 100461, is already higher than yours. So, if the dating of that bike is correct, it's possible that yours dates from 1966 too.

Ian also says that in 1967 European Mark 3s started with number 100247.

A further pointer towards yours being a 1966 bike is the round rear light and toggle switch. In 1967, the light was changed to a rectangular unit with no switch.

P.s Don't confuse build date with registration date. The former can preceded the latter by some time, e.g if the bike sat on the showroom floor for a while.

* All info taken from Ian Falloon's "Ducati Overhead Camshaft Singles".

HTH

Craig

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Craig in France
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Re: Barn find: 196? Ducati 250 in Massachusetts USA

Post by Craig in France » Sun Dec 02, 2018 5:11 am

Dukati250 wrote:
Sat Dec 01, 2018 10:06 am
2) What is a good number for a compression test on these 250 engines?
Hmmm ...

How long is a piece of string? :-D :shock:

Not least because the compression reading depends on the compression ratio of your engine ... Which depends on what piston is fitted in YOUR engine. Which you don't (necessarily) know.
Plus a compression reading is also influenced by other niceties such as the atmospheric pressure where you are and the valve timing of your engine ...

But that said: :)
Let's assume your engine has a 10:1 compression ratio and you live somewhere where the air pressure is a regular 1 atmosphere, and that there's nothing hooky with your valve timing. Then, as an estimate, you should - theoretically - read somewhere around 145psi.

But I bet you won't :). In practice, you'll probably be in the 110 -130 range. Which is probably good enuf, for most uses and for most people. If you're much below, then that's not so good. But chances are, you'll already know that - the engine will be difficult to start, smoke, have no pull etc.

But what exactly are you trying to achieve with doing a compression reading? I know of only two circumstances in which they can be useful:
1. You have a worn engine, but aren't sure if it's rings or valves. In that case you can do a quick and dirty check on the ring sealing by taking a first compression reading, then pouring a small amount of oil down the spark plug hole and taking another reading. If the value goes up by more than 10 % or so, that's an indication of worn rings.

2. By taking a series of pressure readings over a period of time, you can monitor the rate of an engine's wear.

Dukati250
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Re: Barn find: 196? Ducati 250 in Massachusetts USA

Post by Dukati250 » Sun Dec 02, 2018 10:32 am

Craig,
thank you for your thorough and very informative reply.
Right now I am only getting 65psi after couple of compression tests. I still need to check valve clearances and try again.
The bike is getting a spark and fuel but it doesn’t start and I don’t expected to start at such low cylinder compression.
If it ends up needing rings or valves than that’s what I will have to do.
After I get it sorted out and running good I plan on putting a turbo or a nitrous kit on it.... just kiddin’ 😂👍

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Craig in France
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Re: Barn find: 196? Ducati 250 in Massachusetts USA

Post by Craig in France » Mon Dec 03, 2018 12:15 am

Dukati250 wrote:
Sun Dec 02, 2018 10:32 am
Right now I am only getting 65psi after couple of compression tests.
Nah, won't go with that. I have managed to run a twin that had only 90psi on the rear cylinder. But a single with 65?

Nope ... :(

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Craig in France
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Re: Barn find: 196? Ducati 250 in Massachusetts USA

Post by Craig in France » Mon Dec 03, 2018 1:06 am

Craig in France wrote:
Sun Dec 02, 2018 4:03 am
P.s Don't confuse build date with registration date. The former can preceded the latter by some time, e.g if the bike sat on the showroom floor for a while.
Tom Bailey says this:

"The Mk 3 ... never sold well after '65. Because they sold poorly, there were significant numbers of leftovers at the factory, at the dealers and in the Berliner warehouse. Those leftovers remaining in America were frequently titled as the model of the year in which they were sold. Consequently it is not unusual to stumble onto Mk3's manufactured in 1966 or 1967 with paperwork indicating the bike is a 1968 or 1969"

Ref: Ducati Singles First Person, pg 87

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Re: Barn find: 196? Ducati 250 in Massachusetts USA

Post by BevHevSteve » Wed Dec 05, 2018 11:17 am

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