Yet another project

discussion about the 750 Sport and '89/'90 900SS, which share many mechanicals with the Paso series
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nr.
Posts: 12
Joined: Tue Sep 14, 2021 12:22 pm
model: 750 Sport
year: 1991
Location: The Fens, UK
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Yet another project

Post by nr. »

Hi all,

I thought it best to introduce myself before starting with the newbie questions... I'm Neil, from the UK - and have just been gifted a 1991 750 Sport. Well, to be more precise, I've just been gifted a load of boxes with what looks like most of the parts:
Image
Obviously then, lots of work to do! This is my first Ducati (I've ridden many, but never owned one until now) but I do have a Morini Dart in the garage, so I'm not entirely unused to the ways and foibles of Italian bikes.

I promise to read and search for things before asking any questions - it looks like many of the things I've already pondered have been asked and answered here already. But equally, I'm sure there will be many things that leave me stumped.

Progress (and just plain frustration at times) will be documented at https://nronketti.wordpress.com/ - there's a few little things there from my initial fumblings, but hopefully soon I'll be able to get stuck into the bottom end rebuild and something more interesting than just cleaning and cataloguing a million old rusty bolts.

Thanks all - look forward to getting to talk to you,
Kmamac
Posts: 90
Joined: Thu Jul 21, 2016 6:56 pm
model: 906 Paso
year: 1990
Location: UK

Re: Yet another project

Post by Kmamac »

Welcome Neil, looks like a great project. I have 750 sport as well. Not running but sort of nearly next in line LOL. As you alluded to there is a wealth of information on this site and a number of very knowledgeable individuals. I will take a look at your website
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randtcastell
Posts: 339
Joined: Fri Nov 13, 2009 4:33 pm
model: 750 Paso
year: 1987
Location: San Francisco Bay, California USA
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Re: Yet another project

Post by randtcastell »

i read yer website yesterday. i really appreciate the quality of your presentation and the time and talent to do such nice work. Super write up and photo documentation. Thank you for sharing all your effort and baring your soul. :^)
1987 Ducati P750
1973 Honda CB450
2022 KTM RC390
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higgy
paso grand pooh-bah
Posts: 3282
Joined: Tue Jul 29, 2008 9:50 pm
model: 906 Paso
year: 1990
Location: Hilltown,Pennsylvania
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Re: Yet another project

Post by higgy »

:beer: :thumbup: yes a very nice job
Ducati,making mechanics out of riders since 1946
There's no problem so bad that a little fixing can't make it worse! : )
If it ain't broke keep fixin it till it is
88 750
90 906
92 907ie
nr.
Posts: 12
Joined: Tue Sep 14, 2021 12:22 pm
model: 750 Sport
year: 1991
Location: The Fens, UK
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Re: Yet another project

Post by nr. »

Blimey, I can hardly believe that it's been two months already since I posted that introduction - time flies and all that. But it's safe to say that the 750 Sport has been making steady, if not spectacular, progress. I've been trying to keep my blog up to date with photos and reasonably regular posts, but even that has been a bit sporadic.

However, a quick status update. The engine is now kind of back together, mostly... The bottom end all went back together with a set of new bearings and seals, and some careful reshimming of the crank and gearbox. I ended up using the best parts of the 750 Sport and a 600SS gearbox, and while the output shaft is 8mm longer, that doesn't seem to be a problem as the sprocket from my 748 is 8mm thicker, so *should* line up just perfectly. We'll see. The stator is completely rogered, and will need rewinding - but I've got a place reasonably local to me that will do this, so I'm not worried about that. I want to at least test that the engine is capable of running before I worry about it's ability to charge a battery. The clutch slave cylinder is also a cause for concern (heck, the whole clutch is, if I'm honest) but again, let's get things running before worrying whether it can send power anywhere.

Barrels slipped back on with the aid of a home-made ring compressor from an Illy coffee can and a couple of cable ties, and the heads are now also in place, although not torqued down yet. The engine is a big old lump for sure, but it's good to have a full engine on the bench now, rather than three boxes of bits.

Next step then, is to get the heads torqued down and new belts fitted. Then I can pop the motor in the frame, and start to worry about everything else I need to test it. Exhaust all looks fine, carbs are a completely unknown quantity, and the electrics have been hopelessly butchered in the past. I think I'm likely to end up rebuilding most of the loom - which is something I'm looking forward to hugely. I'm at my happiest with a wiring diagram and a soldering iron.

As mentioned, I've been trying to keep things up to date on the blog - https://nronketti.wordpress.com/ - and I'm overdue writing an update there.

To sum up - loads done, but so much more to do before I can even tell if I have a viable project. I dearly hope so, as it's a bloody lovely looking bike.

Ta,
Andrew2
paso grand pooh-bah
Posts: 570
Joined: Thu Oct 27, 2011 7:47 am
model: 750 Sport
year: 1988
Location: Wollongong,Australia

Re: Yet another project

Post by Andrew2 »

Nice work. Thanks for keeping us updated.
nr.
Posts: 12
Joined: Tue Sep 14, 2021 12:22 pm
model: 750 Sport
year: 1991
Location: The Fens, UK
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Re: Yet another project

Post by nr. »

Blimey, it is with no little surprise that I can report that the project just fired up, first time. No leaks. Nothing caught fire. Nothing fell off. Obviously still a long way to go, but this is certainly a bit of a milestone! https://nronketti.wordpress.com/2022/01/08/lux-prima/ for photos and a short video of an overly-excitable idiot :)
nr.
Posts: 12
Joined: Tue Sep 14, 2021 12:22 pm
model: 750 Sport
year: 1991
Location: The Fens, UK
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Re: Yet another project

Post by nr. »

Another slight update - https://nronketti.wordpress.com/2022/03 ... he-nation/ - basically not much has happened with the 750 other than trying to sort out a 900SS front end for it. The practical effects of which are that I now have three fork legs, one bent, one too short, and one OK. The bike has been rehomed to a mates workshop now, which while not as handy for just nipping out to the garage for an hour or two does mean that it's now on a proper ramp which will give my old back a bit of relief. It also means that I have a bit more space for the Dart and 748, so there's a bit of waffling about those two in the blog post too.

Anyhow - hope you enjoy the read - and if anyone EU/UK based has a spare right 900SS fork leg, I'm all ears! I just need to measure up to know what length I need.
Andrew2
paso grand pooh-bah
Posts: 570
Joined: Thu Oct 27, 2011 7:47 am
model: 750 Sport
year: 1988
Location: Wollongong,Australia

Re: Yet another project

Post by Andrew2 »

Bummer about the fork legs. Looking good though.
nr.
Posts: 12
Joined: Tue Sep 14, 2021 12:22 pm
model: 750 Sport
year: 1991
Location: The Fens, UK
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Re: Yet another project

Post by nr. »

Well, after a whole lot of faffing and soul searching (and penny counting) I think I've made the decision to attempt to reuse the original forks, yokes and wheels, rather than convert to 17" front and rear. There are pros and cons to either - the 17" conversion is more future-proof for sure. But I guess there's no point in worrying about this if I'm not sure how I'm going to get on with the bike, right? And if I do decide to sell it once it's finished, well, it'll be easier to sell as standard.

But secretly, I think the main reason is that I just love the look of the stock wheels and I'm not a fast enough rider to need the latest and greatest tyres.

A fruitful couple of hours in the garage revealed that the internals are all pretty much OK - the bushes, in particular, look like they were replaced shortly before the thing was taken off the road. Springs look fine, and other than a good cleanup, it's all good. Seals and O-rings will, of course, be replaced. The stanchions are however, definitely well past the point of being usable. I think the first option will be to get them ground and re-chromed. Philpots in the UK [1] have been recommended to me by quite a few people, and they're not a million miles away, so I may take a whizz over there to see if the ones I have are recoverable.

If not, Paolo Tarozzi list a stanchion of the correct dimensions for a 750SS [2] which could be worth investigating, but I'm not sure how compatible they are. I suspect that other than the size, there's probably precious little in common.

Anyhow - no doubt a blog post will be forthcoming, but I thought it was probably time to post an update here! Progress has slowed recently due in no small part to the current cost of living in the UK. After all, no point in spending a fortune on another motorcycle if I can't afford to put any bloody petrol in there.

[1] https://www.pittedforks.co.uk/contact.php
[2] https://www.brooksuspension.co.uk/fork- ... hion-91-98
nr.
Posts: 12
Joined: Tue Sep 14, 2021 12:22 pm
model: 750 Sport
year: 1991
Location: The Fens, UK
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Re: Yet another project

Post by nr. »

Blimey, three months since the last update - and while there's all sorts of things that I can blame, actually I've just been making the most of a good summer! News in the garage is that firstly, the bike is back up on its wheels:
Image
(Before anyone asks, no, that's not my garage! I'm borrowing space in a mates workshop - cheers James!)

This means that the forks have been rebuilt now, which is probably the biggest thing to have happened, mechanically at least. The stanchions were sent off to Philpots as mentioned in the last post, and after a few weeks were returned in better than new condition. It's really nice to be able to report on unexpectedly helpful and good service, so I'll mention them again - Philpots, in Luton. Happy to give them a plug. The seals and clips were replaced, but I didn't bother with the bushes. They all looked to be in unexpectedly good condition, with the teflon coating still in place. I didn't repaint the lowers either... more on that in a mo. The forks were slipped back together, and filled with Motul oil, and feel pretty good now. Certainly good enough for my mild mannered riding I reckon.

There was also a fair bit of time spent on just a general tidy up of cable routing and wiring and suchlike. And while this didn't achieve a huge amount in the grand scheme of things, it was satisfying to do, and will no doubt make troubleshooting easier when things fail on the test run(s).

This left three main areas to worry about:
1) Hydraulics
2) Charging system
3) Bodywork and cosmetics

I decided to start work on item three first, while I let my finances recover a little from the cost of the fork rebuild. And here I made a simple decision - I'm not going to restore this bike. Rather, I'm going to rebuild it with it's previous battle scars, and use it that way. I like bikes to carry their history with them (see my previous Morini rebuild for example), but originally the plan with this 750 was to go for a complete restoration, given that it was delivered to me already stripped. However, a few chats with friends, and a quick bit of calculating how much money I'd save by not for example, stripping and repainting the frame, soon tipped me in the direction of a rebuild rather than a restoration. I dug the bodywork out of the box, and cleaned it up. It's tatty, cracked, but for the most part serviceable with a bit of work. The screen, however, does need replacing - it's been (badly) sprayed silver with a rattle can in the past, and I dunno about you, but I like to be able to see where I'm going, for the most part anyway. And luckily, they are still available from MRA so it should be possible to replace just that, and continue with the rest of the bodywork with some simple repairs rather than a full repaint.

That's kind of where we are now. Next up will be the hydraulics. I've already stripped and rebuilt the calipers, and they were all fine. The rear master cylinder is completely knackered, and I'll need to work something out with regard to that - my initial digging around has shown it to be a pretty uncommon size, so it's either going to be an adaptor to fit something newer, or a bit more digging. Front master cylinder looks recoverable with new seals. And then it's onto the clutch, which I expect to throw up a few horrors. I already know that I need a new o-ring on the slave piston at least.

As always, I'm keeping things up to date on my blog - https://nronketti.wordpress.com/ - there's a few photos there about dealing with broken bodywork, and a bit more about the decision to rebuild, rather than restore. And I have two sets of spare forks in the garage, in various states of repair. If these are of any use to anyone, get in touch. I'm sure we can work something out.
nr.
Posts: 12
Joined: Tue Sep 14, 2021 12:22 pm
model: 750 Sport
year: 1991
Location: The Fens, UK
Contact:

Re: Yet another project

Post by nr. »

Well, there's been a bit more work on things since I last posted here - to the point where I've actually ridden the thing for the first time. Admittedly, it was around the yard in first gear, but hey, I'll take that as a step in the right direction!
Hydraulics were surprisingly simple - the biggest problem was bleeding the rear brake, but the age-old trick of removing the caliper and just lifting it so any bubbles had a chance to work their way out soon had that fixed. I was expecting all sorts of grief with the clutch, but I think I just got lucky! It all went back together first time, bled easily, and works. The rear brake master cylinder conundrum was solved with the simple act of dropping a note to Stein Dinse with my credit card details. Thanks chaps. Front brakes just went together and worked. I spent a bit (OK, a lot) of time cleaning the disks and calipers, but that's par for the course on any rebuild.
Electrics, so far, have been easy, but I suspect that's because I've been keeping things simple - I know the charging system is shot, and I'll be getting the stator rewound and possibly replacing the reg/rec as well. The biggest headache has been the headlight (in that I didn't have one...) but a unit from a 2MA TZR250 has been adapted, and although it's not been finally buttoned up yet behind the fairing, I don't see a reason that it won't work. Indicators are notably missing from the bike and I'm not sure if I'll replace them as they seem to be hard to come by now. I dunno - certainly for the first runs, I'm happy to flap my arms around.
Bodywork... well, that's still scrappy - but that's OK. If it fits, for the first iteration of this bikes use, that'll do. It may get a lick of paint later, it may not - I dunno. I like my bikes to show their history, but in this case, I don't know what that is, or whether it needs preserving - it came to me as a box of bits so whatever the future holds is up to me, as I have no record of its past.
Next stop, however, is a run up on the dyno to check the fuelling, and make sure that the engine and gearbox can survive full load - I'd rather find out on the dyno than on the road. And if that goes OK, I have a big bill coming for the stator rewind and a set of new tyres - there's plenty of tread left on the existing tyres (and if anyone wants them for period correctness, they're more than welcome if they pay postage!) I don't fancy a set of 20yr old tyres on the slimy potholed roads around here.
All in all then, it's looking reasonably positive right now - I've got a plan next year for a long ride out in the summer down through the South of France and although I've got a lovely 748 in the garage that I was planning to take, well, if this is working by then, I think I may want to give it a proper ride. We'll see.
As always, I'm keeping things up to date on my aged blog - latest post is https://nronketti.wordpress.com/2022/11 ... verything/ - there will be plenty more to come, I'm sure.
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