Author Topic: 1966 Ducati 160 Monza Jr  (Read 24640 times)

Offline DesmoDog

  • Posts: 261
1966 Ducati 160 Monza Jr
« on: Jan 20, 2012, 01:27:34 »
I signed on here a while back and then didn't check back in for a while... here's the bike I was working on when I signed up. I finally got it back on the road in time for Ducstock 2011 at the Barber Vintage Festival last October.  I'm copying posts from another forum to create the build thread so if something doesn't make sense that's likely why. Please excuse the rapid posting...


This project began when I got a 1966 160 Monza Jr as part of a package deal with a '66 250 Monza, which was the bike I  was really looking for. Pictures of the 160 from the ad;

It was a ratty bike to be sure, but the parts it was missing were all things I would have replaced anyway - it looked like it could be a fun project.  The 250 was in about the same condition. When I saw the bikes I was sure I'd leave with the 250 but the 160 depended on the deal I could get. I made an offer for both (all the cash I had brought with me!), the seller accepted, and I took them home. Before I left the house that morning I had told my wife I was going to look at a bike.  She didn't notice I had set the trailer up for two bikes the night before. I called to tell her the news when I was half way home... she's very understanding! I'll show the 250 in a different thread, here's more of the 160.

I wasn't sure what I was going to do with the 160, but figured I'd come up with something while I was working on the 250. I was still finishing up my 750 when I got them so they sat for a while and about all I did was gather parts. For some reason I put the tanks I was considering for the 250 onto the 160.

Stock Monza tank

An older Monza tank

A Benelli Mojave tank

Ducati Mach 1 tank, or so I thought. Turns out it was off an early Sebring.

I wasn't sure what bodywork I was going to use on these but I knew it would be rounded vs the squared off stuff they came with. Most people agree that look wasn't a high point of Italian style. Eventually I decided I wanted to build a 125 Sport replica out of the 160.  I had seen a 100 Sport at the 2005 Motogiro d'Italia and thought it was pretty cool. It was the bike that convinced me I needed to stop talking about wanting a single cylinder Ducati and to actually start looking for one to buy.

Here's a picture of Rich Lambrechts' 125 Sport which provided a lot of inspiration early on:

Even though the 250 was my main interest at first, by the time the 750 was on the road the 160 had become my main focus. The 250 was put on the back burner. The Sebring tank was always intended to go on the 250, but I left it on the 160 as I collected parts because I liked the shape. I wasn't planning on making an accurate Sport replica, just something along the same lines. I found a headlight, fenders, and (fake) earlier tool boxes, but my search for a 125 Sport wasn't getting anywhere.

Repop F3 tanks are out there, but they look a little different than what I wanted. Maybe close enough? While I was mulling over what to do I stumbled across a nice 175 TS(?) tank, so I bought it. I'm not positive it's a TS tank, but I'm pretty sure it's from the late '50s.

Now I had the basis for my bike. Still a lot of mods to be made, but the basics were falling into place.
« Last Edit: Jan 20, 2012, 02:07:49 by DesmoDog »

Offline DesmoDog

  • Posts: 261
Re: 1966 Ducati 160 Monza Jr
« Reply #1 on: Jan 20, 2012, 01:28:53 »
One of the first issues I ran into was the battery tray. The later Monza Jr's have a big indentation in the rear fender to clear the tray, The older rounded fenders don't have that so they won't fit properly on the newer frames. This shot is supposed to show the mounting tab not fitting but if you don't know what to look for I guess it's hard to see... look at the tab on the tray and the hole in the fender.

My first attempt at fixing that was to cut and bend the tabs so the fender could move forward. I suppose that would have worked, assuming I could find a battery that fit, but I decided to copy the tray off my 250 instead. It'd look more like a Sport that way. I made a tracing and started cutting/bending.

The circular cut out on the front was off center on my tracing so I "fixed" it. Then I did a trial fit on the bike.

Yeah, the tabs interfere with the chain guard. Potentially anyway. I ended up putting it in place just a tad higher than it should be and shaved a little off the tabs and it cleared the guard at full compression, no problem. But now I know why the cut out was off center on the 250! I also should have put some stiffening ribs in. it did warp a little when I put it in place. Not bad, but it's not flat either.

The next thing to tackle was the seat. The easy way out would be to buy a fiberglass tail and go with it. But... I wanted something that looked more "factory". The stock seat was just too squared off though. I took some paper and cut out a shape I liked better.

After spending way too much time devising numerous methods of reforming the radius on the edge of the pan after I trimmed it down, I decided to cut and paste instead. I traced the shape out on the pan (black line). While thinking about the best places to cut to get everything to match up so it could be butt welded nice and pretty, I realized there was no need to get perfect joints on this rusty tray that would end up hidden under foam and fabric. I laid out the "cut here" lines (pink) freehand and started cutting. After about two minutes of that I was just cutting where it looked to make the most sense.

When the time came to form the shape, I ended up eyeballing it instead of using the template. I made a new template from the now modified side and used that to check the shape of the second side. First side shaped and tacked:

I finished cutting/shaping/welding and moved on to the front of the seat. The tank I was using was longer than the original tank, so I trimmed it off and changed the profile to match the back of the new tank.

Now I had my seat base and I moved on to building the wheels.

The Monza Jr came with 16" wheels. I didn't like them, and as luck would have it, some 17" San Remo NOS rims off a Benelli(?)showed up on eBay. I didn't want to go with 18" rims because I wanted this bike to look like a smaller scale version of the 250s. I bought a set of the 17s, ordered some stainless spokes from Buchanan's and polished up the old hubs.

Much better than the stock rims. 

There's no real reason to have this photo in here other than it makes me smile. The front fender is an NOS Bronco(?) part from Domiracer. They supplied the NOS Monza Jr rear fender too.

I had issues with my front hub so just for yucks I put the larger 250 hub in there. The spokes are way too long obviously, it's just thrown together. If you look closely you can see the nipples aren't seated and the angle of the spoke holes is off. I like the look of the wheel with that hub, but the spoke holes are too far off to tweak and I already had the spokes for the smaller 160 hub. So... it wasn't to be. Hmm... on second thought maybe the shorter stock 160 spokes would have worked? Nah, the angle of the spoke holes would still be off.

Front hub fixed, I laced it up and installed tires. Then on to the toolboxes. The smaller "Sport" style tool boxes show up on eBay fairly regularly, but they usually sell for more than I wanted to spend. Instead I got fiberglass replicas from Phil at Road and Race in Australia. He also carries steel reproductions. The steel parts are functional, while the 'glass parts are just for show. In order to mount the boxes I had to cut the stock mounts off the 160 frame and weld on some new tabs. Since the fiberglass boxes don't open, I simply installed some wellnuts so I had a way to mount them. More pics of the details after it's painted but for now, the bike in roughly it's new form.

At this point I had to admit to myself I liked the valanced front fender too much to the cut off the panel. But the rear fender didn't really go with it? Once again Rich Lambrechts came to the rescue. More on that later.

Offline DesmoDog

  • Posts: 261
Re: 1966 Ducati 160 Monza Jr
« Reply #2 on: Jan 20, 2012, 01:30:16 »
I decided to go with the front fender as-is, which meant the non-valanced rear fender didn't match. I mentioned this to a friend and he said he had an NOS fender that would work. He also had a Sebring to restore but needed a tank. One thing led to another and a trade was made.

A taillight and some other things were involved in the deal but it was the fender I had my eye on. I had also been playing around with some colors since it was almost time to start painting, but first... another mock! The updated rear end. I had to relocate a couple mounting holes on the fender but other than that it fit great.

The basic shape of the bike was done, time to start painting. (With my apologies to both you dial up users out there, I'm going to start posting bigger pictures.)

My initial color choice was pearlescent silver and pearlescent black, with gold pinstripes. I sprayed a test panel and decided that the black wasn't going to work. It looked more like a charcoal gray with different colored metallic flakes in it than a black to me. I guess I was expecting more of a black that had sort of a shimmer of other colors in it or something? Whatever, I went with a straight black instead. Again House of Kolor paints. The black was great. The silver was a pain to shoot - I'm not a pro and I wasn't expecting how unforgiving it would be. I got through it but on at least one part I basically had to start over after my first attempt. I no longer have any desire to spray a candy color!

Pearlescent silver. I'm not sure the best way to capture the color indoors, it's literally dazzling in the sunlight. (and no, that is not a run you see above the rivet on the right side. It's a reflection)

I screwed up my first attempt at the fender graphics. Oops. The finish looks dull because it is. I cleared it, wet sanded it, put on the graphics, then cleared over it again. The Monza Jr decal didn't make the cut, not that it'd make sense to anyone that knows Ducatis anyway. Neither will the SS decal but so be it, I like how it looks. I probably should have had "160 TS" decals made...

The fiberglass toolboxes come as closed boxes, you're on your own mounting them. I went with welluts.

When I drilled the hole in the front for the knob, I went all the way through the back so I'd have a guide for a hole saw to give me access to the back of the knob for a nylock nut.

I added another hole in back for a third wellnut, and then found some gray plastic plugs at the hardware store to fill the large hole. I wish I could say I planned the color and size match before I started but to be honest it was just dumb luck.

And the reassembly begins!

Forks are on. I was having second thoughts about a silver headlight shell so I bolted on an old black one I had sitting around.

Fenders back on. Bike pushed to the side of the basement?

Offline DesmoDog

  • Posts: 261
Re: 1966 Ducati 160 Monza Jr
« Reply #3 on: Jan 20, 2012, 01:31:16 »
Typically I don't like "fake" features on a bike, but for some reason I put a few on this one. I've already shown the toolboxes. I doubt anyone has noticed but I've also shown a "steering damper".

The larger bikes have steering dampers with a big knob on the steering stem nut. I thought about putting one on this bike but in the mean time I bought a few things at the hardware store, drilled a hole in the nut, and bolted it all together. Crank the nylock down until the tension is about right and install the nut on the stem. The knob is smaller than a stock one but everything on this bike is small, so I think it looks ok.

I also made up a tire pump. Even the reproduction pumps for these things are expensive, so I got a cheapie generic bicycle pump off our favorite auction site and cut it to length. Added a badge decal (that barely shows up) and I was done.

Offline DesmoDog

  • Posts: 261
Re: 1966 Ducati 160 Monza Jr
« Reply #4 on: Jan 20, 2012, 01:32:11 »
Progress came very slowly at this point. It was about two years from when I painted the fenders and frame to when I painted the tank. Numerous reasons for that... I'll skip the details on the junk tank I tried to save.

The first order of business was trying to copy the original graphics. The factory layout wasn't exactly an excercise in precision.

I took some measurements, did some tracing, and tried to make a template.

Time to strip. How's this look for a 50 year old tank?

Primed and sealed

Silver, intercoat clear, and the lines laid out.

Black is sprayed, graphics are on and clear coated

And for the final touch I brought it to Ray Smith, a local pin striper.
A couple last minute decisions I made were
A) striping the toolboxes too and
B) going with red instead of gold for the stripe.
I wasn't sure about red, gold seemed a safer choice. My wife told me I should go with red. She was right.

I've got to say, I was pretty damn happy to have the tank done. There were a couple reasons I had put it off for two years and it was great to have finally worked through it. That milestone provided inspiration to get more work done. As I sorted through more parts I realized I had everything I needed for a headlight so I put that together too.

Next it was time to finish the seat.

Offline DesmoDog

  • Posts: 261
Re: 1966 Ducati 160 Monza Jr
« Reply #5 on: Jan 20, 2012, 01:34:54 »
I already posted this info here but in order to keep continuity with the build thread I'll post it again... sorry if people are sick of seeing pics.

After rounding off the corners of the pan this is what I ended up with. After this I coated the top with POR15 and painted the not nearly as rusty bottom.

With the pan done, I stopped by a local uphostery shop and picked up some foam to create the new seat. It was 1" thick so the seat was built up in layers. I wasn't all that sure this was going to work out well and I didn't take many pictures of the process, but it's not that complicated. First I cut the bottom layer to shape with an electric carving knife, and sculpted the places where the ridges in the pan were.

This worked ok up front, but I put the rear indentation in the wrong spot so I ended up cutting this bottom piece and working on the front and rear sections separately.

For the rear part I laid out a template of the side and front views on some paper. To get the curve, I marked the starting and ending points I needed, and then took welding wire and flexed it to fit between those points, holding only the ends. This gave a nice smooth curve that could be modified by forcing the ends this way or that until it looked right. I only did one half of the front view and transferred it to a piece of wood to get a stiffer pattern. Then I flipped it over for the other side.

I cut out more horizontal layers of the foam to get a step-shaped block in roughly the shape I needed, then glued the sections together. The front profile was relatively easy to lay out on the foam with a Sharpie, but the side profile... the shape I had drawn would only occur in the center of the block. I could either cut an outside template and then try to carve by eye and keep checking, or... I could cut the block down the middle and draw the profile on each side. I took it over to the band saw and cut away.

The rough shaping was done on each half seperately. I used the bandsaw again, first cutting the side profile, and then the front, leaving myself some room for the final shaping. The foam is pretty forgiving, if you mess it up too bad you can always cut out the bad spot and glue in some new foam. Luckily it never came to that but it does boost the confidence. Once both halves were roughly the shape I needed, I glued them back together. I should have taken a picture after this step, it was UGLY. So ugly I was convinced this wasn't going to work so I hung it up for the night.

A day or two later I came back to look at it, and decided to keep going. I took the part over to the belt sander and shaped the front edge so it matched the profile I had drawn out. Then I shaped the center section so it looked relatively smooth. That worked out better than I had expected, so I started sanding away until it was smooth. Once it was close to what I needed, I fit it to the base and glued everything down.

Then came the top layer, which I curved up over the face of the bump to get a nice, flat surface. Once that was fit and glued down, the entire mess was brought over to the belt sander and the final shaping was done. It isn't perfect, but it's close enough! (These pics are from before the final shaping was complete)

Off to the upholstery shop where it was covered in another thin layer of foam, followed by black vinyl. The recovering worked ok but it revealed a mistake I made in shaping the foam. I put a gradual curve between the seat base and the front of the bum stop. There's no good way to make the vinyl follow this curve - it would have been better to go with a sharp edge. Also, I made the hump too big. The seat looks too massive on the bike and to be honest, I'm not entirely happy with it.

I came very close to tearing off the new cover and shaving off the hump, but decided to follow through on my initial plan and add side trim and a badge on the back. I reused the trim off the old seat, polished and then cut and reshaped to fit. The tape is a guide to show where to punch holes in the cover and drill through the metal pan. (The trim strip hasn't been tightened down yet in this shot - it compresses the foam under the cover just enough to fit flush with it = no gaps.)

With the trim on the seat and the rear wheel in place, it doesn't look quite so bad anymore, but I think I'll still end up redoing it. I'm going to wait until I've ridden the bike though, I may decide on other changes to make it more comfortable and it makes sense to do all the mods at once. The tank and seat aren't in the right positions in this shot. Since this was taken I've raised the back of the tank, and plan on dropping the back of the seat a little too.

FWIW - this is NOT a cheap way to do things. A fiberglass tail would have almost certainly cost less, especially when you add in the cost of me redoing it! If I build another bike like this, I'll probably buy a fiberglass tail. I like the fully upholstered look but it would be just as easy to upholster over fiberglass.

Offline DesmoDog

  • Posts: 261
Re: 1966 Ducati 160 Monza Jr
« Reply #6 on: Jan 20, 2012, 01:36:37 »
The big brown truck showed up one day delivering... bright and shiny things, people. BRIGHT AND SHINY THINGS!

Following the advice of some bevelheads list members I sent off some parts to be chromed at St. Louis plating. I'm really not a big fan of chrome but there were a few parts on this that pretty much demanded to be plated... so I decided to test the waters with the kickstart lever and the lever perches.



Oh my, chrome is fun... I'm going to need a bigger box for the next round... my 750GT may get stripped of some items too!

I told the shop I didn't need a show finish on these things, weld imperfections and the like could be left in. With that criteria in mind they did a great job. The only thing I could imagine someone being unhappy with would be the top of the kick start lever. They masked the area that goes into the lever that flips out (Thank you!) but that left a rough edge on the very top of the lever that I had to dress up a touch with a file to make fit. Doesn't bother me, took about a minute to fix. I'm just mentioning it because I know some people are bit more demanding than me...

All the other parts look great with no excuses. Better than expected in fact - one part of the kicker was worn/ground down and they seem to have blended that area into the rest of it better than I thought they would.

Offline DesmoDog

  • Posts: 261
Re: 1966 Ducati 160 Monza Jr
« Reply #7 on: Jan 20, 2012, 01:38:09 »
Test fitting the levers and switchgear. These aren't the grips I'll go with - I've got a pair with white rings on the flanges but they're not going on until it's done, for what I'm guessing are obvious reasons. Apparently I'm not going to have room for a mirror and/or a kill switch on the right side. I have mixed feelings about putting bar end mirrors on if for no other reason than I'd be cutting up the aforementioned grips to make them work. I could put the kill switch inboard of the miter, but that might look dorky. It didn't have one stock so do I really need one now? Hmm...

On the right side, the throttle housing pushes the lever perch about an inch away from the end of the grip. If I put the grip and perch in the same relative position on the left side, it leaves about an inch gap between the two. I've never noticed this on these bikes before. I'm thinking that might be a good place for the mirror to mount? We'll see, I'll just have to play with it more. Putting the levers in different positions side to side to avoid a gap isn't going to fly though.

I also have to find a place to put the tach. I'm thinking of fabbing up a mount that replaces the washer on the top fork bolt, which would put it in about the same spot as on the larger bikes. This would work, but... I've got another idea I'm mulling over.

The tach would also fit in the headlight housing, where the speedo is now. For a speedo, I'm thinking of going with an electronic version that also shows temp, time, and distance. I realize this clashes with the vintage feel, but hear me out. I've been building the bike with giro events in mind. Assuming the unit would be legal in these events (it seemed like it would for the eastern giro when I checked last year) it'd be something I'd want anyway. Plus, the electronic speedo would save me from having to mess with drive ratios on my not-stock size wheels. The unit I'm considering is a Trail Tech Vector:

It would mount directly in front of/above the bars and top triple clamp. I think it could work but I haven't mocked it up yet to be sure. I'll have to do more homework on it.

Offline DesmoDog

  • Posts: 261
Re: 1966 Ducati 160 Monza Jr
« Reply #8 on: Jan 20, 2012, 01:39:20 »
I was playing around with the tach and speedometer mounting on the 160. Two things I discovered were that A) older bikes came with a ring on the right hand fork cover to hold the speedometer cable and B) Domiracer had one of these covers in stock for a whopping $27. That solved one issue, so I was inspired to make a tach mount out of some aluminum I had sitting around. It's basically a copy of the mount the tach came with, modified so it fits on the top triple instead of the bars.

Long story short, I'm not going to go with an electronic speedo just yet, I'm going to give the analog gauges a try first.

Neither the tach nor the headlight shell are at the right angle in that shot but you get the idea. The cable is pressed up against the headlight mount, but there's more than enough room to mod the new fork cover to make it work. 

Offline DesmoDog

  • Posts: 261
Re: 1966 Ducati 160 Monza Jr
« Reply #9 on: Jan 20, 2012, 01:42:16 »
At this point in the project I went about five months with zero progress...  but then I came home from work one day to find a box waiting for me... a box containing my long lost case half! Woo Hoo! (I had sent it out to be repaired and the repair took some time)

That inspired me to start working on the engine.

The heart of this powerful little beast - 160cc of Italin single cylinder fury.

I had to take a pic of this. An open velocity stack on a 160cc single. What's not to like? Imagine this engine only much cleaner with a shiny pipe. Nice....

Random thought: I recently bought a new lawnmower. Self propelled, walk behind. Nothing fancy. It's got a 160cc engine too. I'm not sure how I feel about that.

On the bench. Pretty simple little engine, no? Dare I go so far as to say elegant? Wait until it's clean and shiny, you'll see.

Other side with a few parts removed.

And right about here the ugliness begins. Can anyone spot the result of my not reading the service manual closely enough?

Here's better view.

That really clean spot is where the boss for the kickstart shaft was for about 40 years, until I started screwing with it. Yes, I broke the boss when I used the shaft as a brace for the clutch basket tool. DO NOT DO THIS. The manual warns against it. I glazed over that part. I paid the price so YOU don't have to!