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Old 10-28-2009, 05:57 PM   #1
DesmoDog OP
Desmo's my dog
 
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Joined: Jun 2009
Location: Michigan, USA
Oddometer: 584
1974 Ducati 750GT rebuild - unabridged edition

I’m still a newbie here, and this bike has been seen in a few places on the web before, (including this forum…) but this site seems to be friendly to picture-rich threads and project threads seem to be enjoyed, so I thought I’d do a little more in depth post on the rebuild of my first bevel Ducati. (I got it back on the road a few years ago, this is a retrospective as it were). I’ve got a couple single cylinder Ducs underway now, but progress is slow (probably because I spend too much time on the web) so I thought this one might be a better start. If it’s too much just tell me to shut up!

So… here's my 1974 Ducati "Roundcase" 750GT.

I bought it from a friend after a few years of “is it for sale? Is it for Sale? Is it for sale?” type messages. Finally it WAS for sale. I was in Michigan, it was in Wisconsin, my family is in Minnesota… I looked at it over Thanksgiving and picked it up over Christmas break. Road salt does nasty things to aluminum so I wrapped it up best I could.



Unwrapped and in the basement


The Duc is a springer and the dog is named Desmo. How ironic?

(Yes, I named my dog Desmo. But make no mistake, I like my dogs even more than my Ducs. As for my username, I needed a screen name one night, he walked by as I was thinking, the rest is history)

While not actually round, the "roundcase" sidecovers are more curved than the later squared off "squarecase" bevels.






Nice wiring


Yeah, the bike was a little ratty, but mostly there. I knew NOTHING about bevel Ducs when I bought it and decided that if turned out to be too far gone I could make back most of my money parting it out. At the time I wasn't sure if that was smart. In retrospect is was probably the best deal I'll ever get on a Ducati.

When I bought the bike you could get decent, running GT's for about $6000. I estimated I'd have up to $10,000 into rebuilding this one. I had thoughts of buying one of the retro styled bikes instead, but decided that a new bike would depreciate so I'd lose money there too. Plus, this one would be the real deal.

Over the three + years I spent rebuilding this, roundcase prices shot up to the point I'm sure it's worth at least as much as I have into it now. I'm pretty happy I got it when I did, I don't think I could afford to rebuild a bike like this at today's prices.
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Old 10-28-2009, 05:59 PM   #2
DesmoDog OP
Desmo's my dog
 
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Joined: Jun 2009
Location: Michigan, USA
Oddometer: 584
The teardown begins

I didn't have a tool to lock the engine so before I removed the chain I did this and then broke loose all the locknuts on the crank and cams. The nut holding the countershaft sprocket on was only finger tight so I didn't need it for that.


The inner workings


Belts? We don't need no stinkin' belts!


Most of the aluminum looked like this


Nice air filter!




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Old 10-28-2009, 06:01 PM   #3
DesmoDog OP
Desmo's my dog
 
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Joined: Jun 2009
Location: Michigan, USA
Oddometer: 584
When I bought it we thought the engine was locked up, but when I got it home I noticed the engine would turn backwards but not forwards. Hmm... The bike has sat for years, there's cat food in the air filter, I wonder what kind of crap is in the cylinders?

The front head. You can just see the dirt that built up in it that stopped the piston from going over TDC. (keep in mind this cylinder is horizontal when in place)


And the corresponding cylinder/piston


No major damage done!


She's going to need some new pistons, both of them were scuffed and the rings in this one were locked solid.


The odometer read a bit over 62,000 miles when I got it, and the speedo cable was broken so I'm not sure just how many miles were on the bike.

Apparently flaking rockers are nothing new. I didn't take any pictures of the rockers (which were losing their chrome) but the cams looked like this.


The rest of the engine looked pretty good actually so I'll spare you the pics of the rest of it until rebuild time. Which reminds me, this is a bit out of order. In real time I had gotten some work done on the chassis before I started pulling the engine apart, so enough of the engine for now and on to the rebuild.
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Old 10-28-2009, 06:03 PM   #4
DesmoDog OP
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Joined: Jun 2009
Location: Michigan, USA
Oddometer: 584
The first order of business was replacing dull with shiny. I was enrolled in an auto restoration program when I was doing this so I had access to about every tool known to man. Every night I had class I'd load up a few more parts and slip them into the bead blast cabinet at some point during the evening. About the only part I didn't blast myself was the frame - that got done professionally, while I waited. Money well spent BTW.

I didn't even bring that home after it was blasted, I dropped it off at the powdercoater, along with some other bits. Pretty much anything you see that's black on this bike is powdercoated, except for the headlight mounts.

Ooh, shiny...




And now my first "Do as I say and not as I do" moment. I brought the frame directly from the blaster's to the coater's. Don't do that. Take it home, Look it over, inspect it.

I knew the frame had rust pits on the battery tray, I knew the coater did show quality work. I wasn't building a show bike. I told him to ignore the flaws on the frame.

He did. So when I got the frame home, I discovered these bright and shiny lumps of something on the frame tubes. I was heartbroken. well first I was pissed off. Then I went to build my case on why he was going to fix it for me. It would be easy. I had taken a stupid amount of digital pictures of the bike before I brought him the frame. All I had to do was show him pics of a smooth tube in the areas where the lumps were now.

Except, when I went and looked at the pics? yeah... not so smooth. I thought it was just grunge but apparently someone had done some nasty welding at one point and I was stuck with the aftermath. My fault. That's when pissed off turned to bummed.

So, Tip #1. Examine EVERYTING very closely before taking it somewhere to be refinished. Shiny flaws look much worse than grungy flaws. Trust me on this.

Tip #2 - If you haven't got a decent digital camera, BUY ONE. And use it. Take pictures of everything, from every angle. Capture it all before you touch it and while you're stripping it down. You never know when you'll come up with a question and digital storage is cheap.

Moving along, after thoughts of stripping it again, smoothing it all out, and refinishing it, I came to the realization that the worst of it would be hidden once the bodywork was installed. There was only one spot that would show and it wasn't that bad. I played a little trick to hide it and in three seasons of riding, no one has noticed, or at least mentioned it to me.

Yeah, I got lucky.
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Old 10-28-2009, 06:05 PM   #5
DesmoDog OP
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Joined: Jun 2009
Location: Michigan, USA
Oddometer: 584
I sent the swingarm to Syd's Cycles to get new bushings installed and reamed to fit a new pivot tube.

Centerstand, swingarm, and triples in place.


Next came wheels. I was a bicycle mechanic for about ten years and have built, who knows, 100 wheels? I've probably trued thousands of them. So of course I built them myself. Flanged Excels and stainless steel spokes from Buchanan's replaced the mis-matched, rusty steel rims.


The hubs were bead blasted to remove the corrosion. I thought this was all they'd need, but when I sat them down next to the new rims and spokes it became obvious I was wrong. The hubs still had a sort of greenish tint after blasting, so I took some alloy wheel cleaner to them, hit it lightly with a steel brush, rinsed and dried them off, repeating as needed until they looked presentable. I also polished the center section of the front hub with a little Simichrome. The hubs don't quite look new now, but they do look nicer than they did after being glass beaded and infinitely better than when they were corroded! I used the same cleaning method on the backing plate and the cush drive.







Add some fork tubes from Forking by Frank, a few engine parts, and it's time for yet another mock up. (yeah, the rotor is done here too. Not all these pics will be in chronological order)



And that's enough for one night. More later.
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Old 10-28-2009, 06:15 PM   #6
B.Curvin
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Joined: Feb 2004
Location: Left of the dial. Canton, NC
Oddometer: 2,674
Keep it comin' sir.
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