[DesmoDog]

This project started in 2005, then got shelved. It was going to be my counterpoint to the over weight, over tired, over priced, under braked choppers that were so popular at the time. I started out as a joke, but eventually I realized I had a lot of the parts I'd need to do it, so why not try to find a frame? I was hoping to find something that had been neglected (aka CHEAP) and put the word out on the bevelheads list. The first reply I got was from a buddy who had a frame that fit the bill perfectly (aka FREE).

A couple weeks later we met up at the AMA Vintage Motorcycle Days at Mid-Ohio and I picked up the remains of a Ducati 160 frame that some complete hack had sent him. The swingarm had been removed with a hacksaw, cutting into the pivot bosses in the process. The remains of the swingarm pivot was then removed from the frame with a sledge hammer. From what I can tell, the frame was laid down on the ground and beaten until the pivot was freed. And the subframe was bent. And the passenger peg mount was bent. And the pinch bolt bosses were crushed. And the serrated end of the footpeg mount was destroyed. They succeeded in removing the pivot but the frame was useless when they were done.

No sane person would restore this frame to stock. Maybe if it was a Vincent Black Lightning it'd be worth it, or some old boardtrack racer, but we're talking a square-styled Ducati 160 Monza Jr here. Out came the hacksaw and off came about 8 pounds of bent and battered tubing.

I've forgotten how I came up with the dimensions of the hardtail section. I probably I used a 250 narrowcase frame and swingarm I had, measured where I wanted everything to end up, and did the math. I bought the tubing from some online supplier, brought it in to work and manually bent it on a tubing bender. I didn't have a frame jig, so I drew a straight line on a tool stand I had and clamped the frame to it. Everything was centered and measurements were taken when adding things. It's not a race bike, it'll be fine.

I had decided to mimic the original frame tubes on the chain stays, coming out of the existing brackets with a 90 degree bend and running the tube straight to the new axle plate. I used the hole that the rear brake arm pivot went through as a locator for the new frame tubes. I had to enlarge the holes for the frame tunes to fit. First I turned up a bushing on the lathe so the bit for a hole saw would be centered, then tried to mount everything on the drill press. The test holes went fine with a 1" hole saw but when I went to do the frame things started to go wrong. It gouged the surface a little but I caught it before it was too bad. I got the hole through but it wasn't as clean as I would like. For the right side I went with a 15/16" hole saw and then opened it up with a reamer to fit the 1" tubing. I thought about doing this to begin with but decided the test holes were good enough... turns out it's a lot easier to drill through a flat plate than it is to drill through a bracket on a frame... oh well. Live and learn.

For the seat stays I decided to bolt them to the frame and weld them too after everything was in place. Belt and suspenders, I know, but I don't see a downside. If I don't like how the bolt head looks, I'll grind it down to match the profile of the tube, braze over it, then smooth it all down so when it's painted no one will be able to tell it's there. The tabs are there to mount the pivot for a sprung seat.

 

[DesmoDog]

I got the lower frame tubes (we called them chain stays when I worked on bicycles?) done first to position the axle plates, then made the top tubes (seat stays) fit. When I bent the tubes, I left them long. I was about to cut the front section to size when I realized it would be easier to find 90 degrees with the long section still there. So, I cut the rear section to length and slotted the ends for the axle plates before I cut off the front section to fit the frame.

I don't have a mill so I put an end mill in the lathe, fit up a vise, and cut the slots in the chain stays. The set up isn't nearly as rigid as it should be, but for what I'm doing it works as well as any other method I would use.

The chainstays are two 90 degree bends that butt together in the middle. There is no access to some of that joint to weld, so I ended up making a sleeve that would fit between the frame brakets and slide over the frame tubing. I slotted it so I could see the tubes inside and then welded everything together once it was positioned. There may well be a small plug inside the tubes too, I hihgly doubt they'd line up that well if there wasn't. It was a long time ago, I've forgotten.

For the axle plates I drew up some ideas that night and settled on the designs shown. They aren't the same because the left side has to incorporate an anchor for the brake plate. That's what the slot in the front is for - a bar will be welded in there, which will fit into a slot on the hub when it's installed and keep the brake plate from turning when the brakes are applied. I also left a tab on top for the fender mount.

I slotted the axle plate the same way I did the tubes, it just took longer! Actually that isn't entirely true. The slot for the axle had to be 0.60" (Yeah, I should be stating that in mm but my tooling is in inches, so...) and I didn't have an end mill that size, and didn't want to be cutting that much metal anyway with my hack machining set up, so I first drilled a 0.50" hole where the end of the slot needed to be, then cut a 0.50" slot out on a bandsaw. Once that was done, I cut the slot to size with an endmill in the lathe, dropping one surface and raising the other in two separate passes.

A lot of measuring and tacking and clamping. Midway to having the tubes set in place.

 

[DesmoDog]

Once the frame tubes were in place it was time to start bolting stuff on in a long line of mock ups. That's about as far as I got before I put the project on the back burner and now it's been sitting for over ten years. I just recently pulled it out again and am thinking I'll build it up as far as I can with parts I have on hand to try and figure out just what it would take to get on the road.

This is how it looked this afternoon when I stopped messing with it.

Here's an earlier mock up with a little different look.

Earlier today I was kinda digging the valanced fenders but now I'm back to thinking non-valenced. Bars will likely change, I'd like them a little taller but don't have anything suitable to put on there right now. The tank will likely stay because it's the only narrowcase tank I have left. Obviously the seat's not mounted in the correct position yet.

So that's the status of my long dormant Ducati bobber project. A few comments:

1) If I was starting this project today I'd do some things differently, but that's to be expected
2)There are braces between the tubes that aren't shown here.
3) The engine is a 250 I had left over after I upgraded my "real" single cylinder project to a 350. It's been dormant just as long as this one...
4) The majority of these parts are leftover from previous projects. The forks and seat are about the only things I bought specifically for this.
5) I've forgotten what else I was going to say. This may see progress soon, it may end up stuffed in the corner again. No promises.

 

[Tinsnips]

Very cool.

 

[DucDave]

Very cool.

Agreed, this will be a fun one to watch! Don't see many bobbed Duc singles.

 

[DesmoDog]

Was it Pirsig who wrote about gumption traps? One of the things I've spent WAY too much time thinking about how to fix on this thing was the bent/battered footpeg mount on the left side. Long story short, yesterday I decided doing anything was better than doing nothing, and that peg was getting fixed before anything else got done. After staring at it AGAIN for way to long trying to figure out how to make a simple frame to put a jack in there and force it back in positon (yes, seriously) I grabbed an old swingarm spindle and slid that in the frame, then slid an old fork tube over the peg mount. Push down on the fork tube, pull up on the spindle... and feel the footpeg tube give a little. Cool! Still not right though. Try again.

And... I broke the tube off. Well, not entirely, but it cracked. Whatever, not the end of the world. Most of my imaginary fixes involved cutting it off anyway, this was just an attempt at a quick fix. So I tore it all the way off the frame, and discovered it had been cracked for years. I also admitted to myself the end of it was too beat up to use anyway. It would have been a hack fix. Breaking it off was the best thing that could have happened. If I can break a foot peg mount off a hardtail frame by pushing on it with my leg, it wasn't a decent mount to begin with.

Peg mount is the hole in the middle. You can see on the right side of it where the tube was already cracked and rusty. And also the broken off tube.

Today I went downstairs with the intention of fixing this once and for all. I found some 3/4" round stock which was dang close to the ID of the foot peg tube. I cleaned up the break on the frame, cleaned up the inside of the tube, then turned down about 15mm of the round stock to fit into the frame - I used a slight hammer tap fit... after the oh crap I turned it down too far fit on my first attempt. Measure twice, cut once. oops.

Then I started measuring things to figure out where to cut the tube off of one of my other projects to weld onto the end of this. I chickened out though. I'd rather not cut that frame, even if I won't ever use those mounts after having spent years (literally) working on rearsets for it. (See Gumption trap, above). So instead of finishing like I said I would, I posted on a couple Ducati forums looking for the part I need. SOMEBODY cut those off when they made their cafe racer. If nothing surfaces in the next week or two I'll cut what I need off the frame for my 350.

So that's where it sits now. Not much of an update but this could take a while and I didn't want you guys to sit there clicking "refresh" all week awaiting new info...

EDIT: I'm realizing most of you have no clue what I'm talking about when I say the end is too messed up to use. The mount and the peg both have a serrated mating surface so the peg can be indexed at the right angle and not slip. I have no idea what these little ends things are called or if they can be sourced anywhere.

The teeth on the end of the mount have been smashed flat so only about half of them would mesh with the peg, and the end isn't flat anymore either.

Why in the hell the bashers didn't give up before destoying the frame is beyond me. Some people should not own tools...

 

[DesmoDog]

I still haven't found a foot peg end but have one or two more sources to check before I cut one off my other frame.

I decided to pivot the rear brake pedal off of the centerstand shaft, which meant I needed to make a new shaft to accomodate both. I was going to just use a longer 16mm dia shaft, but when I went to take the brake pedal out to 16mm (from 14) I changed my mind and turned down the end of the shaft instead. There wasn't as much left of the pedal boss as I expected. I needed to shorten the boss to make up for the added thickness of the centerstand, so the part of the boss I started opening up got cut off anyway. The kicker is, I'm not 100% sure I'll be using the centerstand, so may have to mod the shaft and add a spacer to move the pedal out again! I still have to shorten it a little but the main question of "how is this going to work" has been worked out.

I also kinda sorta figured out the seat mount. It's not ideal but it should work. I have 4" seat springs now but may buy a set of 5" springs to cut the mounts on the frame down. I still have a couple things to work out there.

As mentioned, I may not use the center stand. It's too tall for one thing - I can cut it down but we'll see. The side stand works fine but doesn't look so great IMHO. I also have to relocate the spring for the centerstand since the new frame section gets in the way of the stock spring location.

This is how it looks now, sitting on the sidestand. I know, it doesn't look like much has changed, but I'm telling you it has.

Oh yeah, that picture reminds me. The rounded front and rear fenders I have for this are both NOS parts (not the valanced front that is shown, I have a non-valanced front for it too). I'm not too excited about cutting them up so have also reached out for damaged fenders to use instead. I have a set of fenders off a later, "square style" Monza that would fit the bill, but I prefer the rounded ones. Then again, the tail light I wanted to use fits the flatter fenders but not the rounded ones, so who knows where this will end up.

 

[DesmoDog]

It doesn't look like it, but I made progress on the seat mount this week. I ditched the seat bracket I had made and went with something else. I made some Delrin bushings to put on the top of the springs so they could get bolted to the seat without squeaking and rattling, and then today I cut down the frame mounts by about 20mm. It looks pretty much the same but I don't even want to add up how much time it all took. I've stopped worrying about that though. I'm retired now, who cares how long it takes?

Am I the only one who will sit and stare at some detail for an hour before I spend ten minutes just doing what I've been thinking about? Seriously, there have been times when I've spent more time contemplating something than what it would have taken to change it, and then rebuild it if it didn't work.

And every time I convince myself I'm going to cut down the valanced rear fender, I then put the skimpy one on there and decide the valanced fenders aren't going to work! Yeah, I know, a couple more "hey, nothing's changed" photos. This time I mostly wanted to get a valanced vs non valanced rear fender photos next to each other so the next time I think about pulling the damn thing off the shelf and trying it again I can just look at the thread and decide it's still not going to work.

Oh yeah, I also welded the frame brace in. The test welds went great. The actual frame weld, not so much. Not a disaster but I think I'll break out the eraser and redo one side at least... Structually it's fine. Aesthetically... not so much.

 

[DucDave]

Am I the only one who will sit and stare at some detail for an hour before I spend ten minutes just doing what I've been thinking about?

You are not alone!!! But it usually turns out better that way. My vote is for the skinny rear fender but my opinion is biased from my own project (below) a while ago. Yours is more of a bobber which does lend itself to the valanced fenders.

 

[DesmoDog]

The skinny fender keeps winning all my elimination mock ups. I'm pretty much over worrying about cutting it up at this point. Stillnot decided on th front fender, I'm almost thinkning the full size valanced fender might make the cut? We'll see.

I've been working on this thing, but none of the progress would show up in pictures. The seat is worked out with everything tacked in place. I bit the bullet and cut the footpeg mount off my other frame, so that's also worked out with everything tacked in place. And then I gave in and ordered some rims for it. They aren't the style I wanted but they were in the price range I could handle. More details when they show up and I get to work on the wheels. I just hope I can find all the old spokes so I don't have to spring for new ones. DANG Buchanans is proud of their stainless spoke sets... I mean I've used them before and like them a lot but were they always $100 per wheel???

Now I've started planning the electrical system. I wanted to get a battery box so I could hide a modern battery and maybe a fuse block or something in there, but I can't find the size box I used on my 160 and don't like the stuff I can find. Hmmm... I pulled an old SAFA battery off the shelf that I had bought it for my 160. It's an NOS part from who knows when, Cosmo was selling them back in the day I think? It's not something I'd ever use because 1) people who did try to use them reported they didn't last very long and 2) I despise old school flooded acid batteries.

But dang it's a nice size to fit the bike. I took some measurements and started poking around the old interwebs, and wouldn't you know. One of the popular modern batteries people are using on these things should fit inside the case of the SAFA battery. Well, if that case was hollow anyway. Alright, let's see what how these things are made then. Just to clarify, this battery is old but has never been filled with anything. No acid or voltages involved. There is some lead involved, but I wear an old respirator when I do stuff like this because of all the dust anyway.

Here's the battery as it's sat for the last 50 years or so. That thing behind it is a top cover that will hide all the modern parts inside.

First step was to scrape the tar off the top and see how this is put together.

I thought the top was one molded piece, but when I started cutting it I discovered it's three seperate covers that are just sitting on the cells, the tar held it all in place.

Bash the covers off and the cells pull out in one piece. Much easier than I was imagining.

Once the case was empty, I had to deal with the internal walls that seperated the cells.

I ended up cutting slots in walls and then breaking them out in pieces. They were brittle so breaking them was easy, but I tried to be careful not to break the outer walls. There is one spot where the break went into the wall but didn't go all the way through. For the most part I got to where there was some left on the outer wall and then shaved that off with a wood chisel.

So there it is, a dummy battery box that looks old school. If all my measurements are correct I'll have enough room on the end to place a terminal block if not a fuse block. Next up I'm trying to source a regulator for it. I was looking for a new, small, cheap part off a CB125 or something, but may have found an original one that I wouldn't have to hide. Which is good because as I recall the originals aren't small.

 

[DucDave]

Nice work DD! That will look great.