New to Ducati Singles - Intro

[guzzijon]

Hello everyone,

My name is Jon and I am new to Ducati singles. Last weekend I purchased two very rough 250 Ducatis. One is a 1963 Ducati 250 Scrambler, the other is a 1963 or 1964 Ducati 250 Monza. I first spotted them at a big automotive swapmeet. The previous owner has messed around with various Ducati singles going back to the 1960s and used them for everything from commuting to work to roadracing (sometimes on the same bike).

The reason I'm unclear about the year of the Monza is because the guy I bought it from said that based on running the numbers on the bike, he thought it was a 1964. But when I found a website that was a registery of the engine numbers, the Monza's numbers showed as being for a 1963. The frame tags on both bikes are worn to the point that only a few letters or numbers are still legible. Both bikes were in Scrambler trim with trials tires and dirtbike handlebars and used as trail bikes but only one has the Scrambler frame brace.

Enough rambling, I am completely new to these things I will try not to ask too many stupid questions. I've been into vintage Guzzis for about 15 years but I'm excited to learn about something new to me.

These are projects for my wife and I to work on. In fact, the whole thing was her idea, so I'm going to run with it! We will attempt to restore the Scrambler to stock and we will make the Monza into more of a restomod picking bits and pieces of stock and aftermarket to suit our tastes. We realize we are probably in way over our heads and it will take us years but it will give us a fun project and distration to work on together.

[JimF]

Welcome Jon,

Are you in the US?

Identifying the year of a Ducati single is almost always speculative. Seemingly back in the day a motorcycle that sat on a US dealer's floor or stock room during the passage of a calendar year would be titled at the point of sale as whatever model year it was sold; that is to say a dealer could have a motorcycle made in '65 and sell it in 1966 as a 1966 model. At this point the official vehicle title is a year off.

There are things you can do to narrow down the year - if the motorcycle is original you might be able to match the tank/fenders/seat to some Ducati advertisements for certain models in certain years.

As you have found, there are published registries for engine numbers that might help to refine the year of manufacture, but unless a contributor bought his bike new the data in the registry may be erroneous.

The foil sticker on the frame is generally understood to be a tag applied by the US importer to comply with Federal and/or State laws. Here again, the data on the foil tag was typed on in New Jersey, so bikes that were shipped late in one year and arrived at the US port in the next year almost surely got tags for the current year which of course throws inaccuracy into the whole thing way back then.

If you take the front wheel off there is a boss of metal on one of the forks that keeps the brake plate still. You will find a date code stamped on the fork (month and 2-digit year.) This will tell you when the fork was made. It's probably safe to presume the fork was assembled onto a motorcycle soon after. Of course if the forks have been changed out in the motorcycles lifetime that date code could be irrelevant.

Probably using all the items above will get you to the right year plus or minus a year.

Jim

[guzzijon]

Interesting information, thanks! Yes, I am in the U.S. I guess I should have mentioned that in my introduction post. I'm located in Oceanside, California.

The engine numbers for both bikes fall into the range of numbers on the registry for bikes produced in 1963. So maybe based on what you said, I'll just go with that and consider them 1963s. There's not enough left on the bikes to really tell me much about them. The Scrambler has the extra frame hoop, a beat up Scrambler tank, and a beat up Scrambler rear fender, the one I think is a Monza has a Monza tank and no extra Scrambler frame hoop.

The guy I bought them from said that the Scrambler motors had cylinder heads with bigger ports and bigger valves on them than the Monzas. He also told me that the Monza I bought has the Scrambler-type cylinder head with the bigger ports and bigger valves on it right now. Any truth to that about the Scramblers having different cylinder heads?

Also, the guy I bought the bikes from said that the Monza I bought had coil springs instead of hairpin springs put into the cylinder heads at some point and that this was a modification that some people did back in the day. He told me that it's possible that this is an indication that someone may have been into the Monza's motor at some point to change the cam to a hotter one. Just speculation until I can get the motor apart to see the cam. But even then, I'm not sure what to look for to indentify a stock from a non-stock cam.

[JimF]

Many others on this list know better than me, so check back for more and often times better advice...

There is a 250 cylinder head with bigger valves that was used on higher performance models, specifically the Mach 1 and Mark 3.

Before those models the Diana was the high performance offering but I am unsure if the valves were larger in that model. Someone here will likely know.

Whether or not any other models got heads with larger valves I don't know, and perhaps the seller was just telling you what he thought you wanted to hear to make the sale or maybe he was honest and you do have a head with large valves. You can know for sure when you take the head off.

If the head has larger valves (either stock or as a retrofit) I would imagine to reap the benefit the carb would have been up-sized. What size carb is on the head? That might give you some clue as to if the head has larger valves. The Mach 1 and Mark 3 came with 29mm carbs. I think the Diana came with a 27mm carb.

The cams are coded with a color to aid in identifying them.

Jim

[guzzijon]

Carbs are missing on both bikes.

Previous owner started talking about the cylinder heads after the deal was done and bikes were loaded into my van so I don't think he was trying to sell me on anything. I was just picking his brain trying to get him to tell me everthing he knew about the bikes before I drove off into the sunset.

[ajleone]

Yes, the NC 250 scramblers also had the large valve heads with 27mm SSI carbs.

Welcom to the list !
Tony

[guzzijon]

Thanks! And thanks for the info!

[dav]

Mate, is there any chance of you posting some pics of your bikes....please.

& welcome aboard

[guzzijon]

Thanks for the welcome! I'll post some today after work. I have to warn you that they look like total scrap piles.

[double diamond]

Hi Jon,

I saw those two bikes at the Big 3 swap. The scrambler is a very early model 4 speed based on the engine serial number located on the left case and the “DM250” on the right. Also, the tank on the bike (as I recall it was painted blue?) is an early SCR. These tanks were used for only one or two years until the SCR adopted the later style tank (the type on your other bike). I don’t think the rear fender was original but there was an original front sitting on the trailer. Scramblers do have a larger intake port than Monzas since the SCR has a 27mm carb and the Monza a 24mm. Obviously, it’s pretty easy to open up the intake port on a Monza to match whatever carb you’re running. The basic head casting is the same for all the narrowcase models but the valve seats and ports are machined to different specs depending upon the model the head is to be installed on. The stock Monza intake valve is 1mm larger than the SCR (37mm vs 36mm) but the SCR valves were made of better material than the Monza valves. The Monza uses a set screw type valve adjuster with a captive ball at the valve end (which your Monza has; the seller had removed the valve cover when I saw it) and it had a coil spring conversion. The SCR should have a solid rocker but that bike you have is so early that it might have the set screw type. I always assumed any SCR should have a solid rocker so let us know when you get the valve cover off. You may indeed find a non stock cam in the Monza. The stock Monza cam is pretty mild. If there’s a dab of paint on the threaded end of the cam, it would be purple for a stock Monza cam. SCR cam would be white. But the paint is often missing. The engine number on the Monza isn’t especially early. It does have the 7 fin hubs of earlier bikes but it could be a 5 speed which would make it a ’64 at the earliest. The year stamp on the fork will be some indication, but you won’t really know until the engine is disassembled. Matt