New 250 Project Adventure

[Snakeoil]

Not sure if I have introduced myself here yet or not. Gray hair, ya'know. So, in case I haven't...

I'm a retired guy that likes to play with old motorcycles. Have done frame up restos, original paint refurbs and ride all my machines. I really have no use for very pretty bikes that I don't ride. But I do like very pretty bikes that I do ride.

I've been wanting a 250 Duc for sometime now, but was not pursuing it seriously. Last year I was given a complete 160 with a stuck engine and spare head/piston/cylinder and it got the juices flowing again. The 160 is all their but rather fugly. Plus, all indications are that they are pretty gutless and I have a CB160 that would run circles around it. So, the 160 might become a donor bike for my new project.

Today, I brought home my first installment in a 250 project. It is a chassis and engine bottom end. My friend Peter and I are taking a ride in a week or two to his other storage container and dig out the rest of the 250 stuff. I get my choice of tanks and other farkles to hopefully end up with a complete or close to complete bike. As I mentioned, I have the 160 to use as a donor for things like kick start, shift lever and such.

Peter has a mod to replace the hairpin springs with standard valve springs. He’s also rebuilt several of these engines, including a flat tracker he built years ago. So he's a great resource for tech support when I dig into the engine. My other buddy Lance was a Ducati dealer for years and will have the special tools if any are needed for the engine rebuild.

The aluminum bits on the chassis like the headlight ears are in really nice shape. No furry aluminum bits. All parts were always stored inside and dry.

Here's the chassis and lump. 160 is behind it.



Curious if there is a serial number registry. I need to search this site a bit so might find it on my own. But if not here, does not exist?

Thanks and regards,
Rob

[Nick]

Cool. Please keep us updated on your progress.

Re the valve springs, I've put quite a few miles on both my 250 Diana and 350 Sebring over a period of many years, using both bikes for daily transportation, sport riding (sort of), etc. (No queens in my garage either!)

I bought both bikes in very used condition and both still have the original hairpin springs.

[Bevel bob]

I agree with Nick. The orriginal valve spring layout was good enough to win a zillion races over the years ,my 250 revs to 10,000 with 40mm valves (not that I do it much!) Unless you are building a full race motor (which won't be competative these days) I would not bother. You can build a pretty little bike that weighs nothing with good handling ,braking, with a 90mph top speed with zippy acceleration if you don't overdo the tuning. Something like Mach1/ mark 3 NC level of tune will give you that. I would happily swop my big carb and race cam for sensible stuff to improve the useability round town.

[Snakeoil]

Great input guys. I'm really drinking thru the fire hose here with this bike. Opinions are like belly buttons, right? I was thinking that with so many around that are still running great that maybe Peter's valve spring mod is not really necessary.

I'm trying to understand the model nomenclature. I assume a DM250 is a Monza. A DM250MI is a Mach 1 and a DM250M3 is a Mach 3? I did a bit of research on the web last night. But there is not as much stuff out there on these as there are on more common brands/models. I'm a hound for information on anything I own. Learning is like candy for me.

This looks like it will be fun rebuild. Not sure what path it is going to take. I really like the look of the old GP bikes. But having owned bikes with clip-ons I know that they are much more fun to look at that ride unless you are on the track. I'd love to build a mini-supersport like the silver one in the gallery. But I don't think it is a practical idea. I'll be riding this bike in tiddler events and giros and two days hunched over behind a fairing has my back talking to me already.

I noticed that there is no sub-forum for resto projects. Is there a preferred area for resto threads? I tend to be a bit obsessive with photos and descriptions. Don't want to be a hog here.

We'll see.

Rob

[amartina75]

Welcome to the forum and good luck with your project. Sounds like you have some good friends to help you out which is good. I think you'd be hard pressed to find a single person on this forum that would recommend doing the valve spring conversion on a road bike. I also don't think anyone would recommend picking apart a mostly complete Monza Jr. to get a few parts off it, considering the parts that would be a direct swap are few. If you really don't want to have the Monza Jr. as a project I'd recommend selling it to fund your 250 project. There are plenty of good used parts on ebay and several good parts suppliers in the States and Europe, also people on here occasionally swap parts to help each other out. I'd recommend not chucking anything in the garbage that might be useful to someone, or getting rid of anything until your finished and sure you won't need it. Also for parts, if you're not worried about originality some of the other Italian marks have good parts that can be used on a Ducati such as lights switches fenders gas tanks carbs and more.
good luck
Aaron

[Snakeoil]

I never throw anything out. I did when I was a kid and I'm still regretting some of the stuff that went into the trash.

The Monza Jr was a freebie and although it looks decent in the pics (they always do) it is pretty rough. But there are not many parts I would want off it anyway other than maybe the shifter and kick start. And the kick start was missing on the bike and another friend gave me one of his. He has the same bike in worse shape and has expressed an interest in the 160.


regards,

Rob

[Jordan]

It's easy to see what parts interchange between different bevel Ducati models, because they have the same part numbers in the factory parts lists.

[Snakeoil]

Today was get the chassis cleaned up, strip off the various parts and remove the lump. Went pretty well.

Brake switch tested okay. Horn went BEEP. Wiring harness looks like it is in pretty good shape. Might be able to reuse after I give it a good inspection. Pretty simple harness. Easy to make from scratch.

The voltage regulator had a hole worn thru the tin cover from something rubbing on it. It feels like the factory filled it with lead. I imagine SOP is to replace it with a modern solid state reg/rect.

Rims and front fender were pretty rusty. But after I cleaned up the chassis, I hit both with a little steel wool and it appears that they will clean up nicely. Rear fender is in a very nice shape. But it appears someone has drilled four extra holes in it and not centered on the fender. No tailight on the bike so not sure of the way it mounts. My 160 taillight would not use the holes on the 250 fender. Need to start looking at the parts manual.

Here is the chassis right after I removed the lump.


And the lump



Here is the chassis back on the lift after getting a good scrubbing and pressure wash. Hubs cleaned up nicely. Will be a snap to polish.



Here are before and after pics of one rim.




Fender shot is both a before and after.



I have a couple of questions. Answers might be in the manual for the first one.

What is this little tab? Is this a stop for the center stand, which is missing at present?




This is a shot looking down at the footpeg mounts. The left appears to be bent. Is it, or is this a factory bend?



I know, kinda mundane first post. But that's how these things start out. Mundane is actually much better than surprises.

regards,
Rob

[halfpast]

Thanks for posting Rob. It's inspiring to see others out there working on these beautiful but rare bikes. Good luck moving forward.

[Snakeoil]

Thanks. I like doing these resto threads. I like to think it helps the next guy.

Started to disassemble the bottom lump today. I do not have any pullers or the same selection of large sockets at my camp that I have in the shop at home. So I hit a dead end not too far into the engine. But I did find a few intesting things.

With the primary cover off, there was a small amount of sludge in the bottom of the cases. It was fairly soft and wiped out with a paper towel. Here's pics of what was in there.





I found my first sign of damage. Too much crud on the outside of the primary cover to have noticed this. But when I pulled it off, I found this inside.




Here is the outside with the crud wiped away.




This kind of answers my question about the foot peg mount. I'd say it is bent and the dent/crack in the primary cover is from the brake pedal.

I noticed these paint dots on the rod. Not sure what they mean. Might be a balance code identifying the rod weight. Maybe it is the small end bushing fit. If somebody knows, I'd appreciate knowing the significance.




Pulled the clutch plates out. The look pretty good. A little corrosion/discoloration where the fiber pads stuck to the metal plates. Should clean up fine. But, I found another surprise with the plates removed. Down in the bottom of the basket I found these.



I know they sure do not belong there. They look like the clutch release rod balls. But both of those were in place where they belonged. So, these might be two original balls that somehow ended up in the bottom of the clutch hub accompanied by the builder saying, "Where the Hell did those damn ball bearings go?!" Now we know.


Next issue I ran across was this. Not sure it is an issue or not. I need to check the manual. The lower bevel drive assembly slides freely up and down in the case. I can see that the tower when bolted to the case holds this in place so it may be a non-issue. I the photo I'm holding the assembly up with my thumb.



Pulled the ignition drive gear out of the case and that was a far as I could get. No strap wrenches to hold the clutch hub and no impact wrench to loosen the nuts on the shafts. So, I cleaned up and made a wooden engine stand after seeing the stand shown in the manual. Fits in a plastic tub I have, which will catch any errant parts or residual oil drips.




Started to make a list of missing bits and pieces. Maybe tomorrow I'll take the shifter assembly apart. Or maybe I'll go fishing.

regards,
Rob