A 750 Sport from 1989

discussion about the 750 Sport and '89/'90 900SS, which share many mechanicals with the Paso series
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L Nino
Posts: 5
Joined: Fri May 14, 2010 10:27 am
model: 750 Sport
year: 1989
Location: Belgium

A 750 Sport from 1989

Post by L Nino »

Greetings from Brussels, Belgium. Thank you very much for this forum which is a goldmine of useful information.

May I introduce you to my 750 S from 1989. My other bikes are a cafe-racer based on a Guzzi 1000 Strada of 1994 and another cafe-racer made of a 650 Cagiva Allazzura.

I bought the 750 two years ago, and it already had its Boss exhaust and 17’ wheels, but still had its Weber which I had replaced with two Dell’Ortos 36. The frame is not original. It is made of the front part of a 91-98 model, on which a battery case and the rear part of a 88-90 model were glued. It seems untidy from a conceptual point of view but the work was done neatly. Anyway, I have since found a complete original 1989 frame which I will mount at some point in the future. The bodywork was in poor shape, so I restored it and sprayed it. Since I am not a fan of the original deco, I draw inspiration from the F1 Laguna Seca and Montjuich. A few other things were changed for aesthetic reasons, but without straying too much afar from the original.

The bike runs well but I think the carburettor settings should be changed. It pulls tremendously well at times, particularly around 6000 RPM, but when I open the throttle at around 4000-5000 RPM the response is not immediate and engine seems to gasp for fuel. Also, it tends to sputter when the throttle is only partly open. I was very happy to find the best carb settings in this forum. I’ll try them and tell you what.

I like the look of this machine. It is slimmer and rawer than the later models, and of course closer to the F1. Not to mention that it is an excellent ride, perfectly adapted for road use.



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ducinthebay
paso grand pooh-bah
Posts: 1323
Joined: Sat Sep 03, 2005 12:00 am
model: 750 Sport
year: 1990
Location: SF Bay Area

Re: A 750 Sport from 1989

Post by ducinthebay »

Nice bike. Looks good. I'm not sure I quite understand the modifications to the frame, as from the pictures, it looks like a stock 750 Sport frame, but that's my view from here. There are no known issues with the stock frame. the geometry is pretty good, and I have never heard of a frame failure or cracking, unless it was crashed hard. I see these frames for sale on occasion, and they are always reasonably priced. Not much of a demand for them.

Cheers, and Welcome.
Duc in the Bay
1990 750 Sport x2-Rosso Blanko (900ss copy) & Nuovo Nudo (Scrambler project)
1991 907 -mostly stock
2002 ST4s - Lots of mods.
Tamburinifan
paso grand pooh-bah
Posts: 1527
Joined: Thu Jun 21, 2007 12:00 am
model: 907 I.E.
year: 1991
Location: Gothenburg, SWEDEN

Re: A 750 Sport from 1989

Post by Tamburinifan »

Looks good & welcome to this Forum!
Gert

907 I.E. -91
M900 -97
MTS 1100s -07
L Nino
Posts: 5
Joined: Fri May 14, 2010 10:27 am
model: 750 Sport
year: 1989
Location: Belgium

Re: A 750 Sport from 1989

Post by L Nino »

ducinthebay wrote: I'm not sure I quite understand the modifications to the frame, as from the pictures.
If you look at the first photo, right under the Ducati logo on the tank, you'll see that there are two diagonal bars instead of one. This transformation was already done when I purvchased the bike, and I already have a stock frame.
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ducinthebay
paso grand pooh-bah
Posts: 1323
Joined: Sat Sep 03, 2005 12:00 am
model: 750 Sport
year: 1990
Location: SF Bay Area

Re: A 750 Sport from 1989

Post by ducinthebay »

Yeah, now that you mention it, I do see the difference. Seems like a lot of work, I wonder why the previous owner went that way, unless he couldn't find a good frame. What size rear wheel/tire are you running? A 4.5" or 5.5" ?

Cheers,
Duc in the Bay
1990 750 Sport x2-Rosso Blanko (900ss copy) & Nuovo Nudo (Scrambler project)
1991 907 -mostly stock
2002 ST4s - Lots of mods.
L Nino
Posts: 5
Joined: Fri May 14, 2010 10:27 am
model: 750 Sport
year: 1989
Location: Belgium

Re: A 750 Sport from 1989

Post by L Nino »

The tire measurements are in millimeters. At the rear I have a 160 and at the front a 120. 160mm is 6.2'. In fact I'd like to fit a leaner tire. Do you think 4.5 is OK ? It seems very narrow.
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paso750
paso grand pooh-bah
Posts: 5558
Joined: Sun Jul 18, 2004 12:00 am
model: 750 Paso
year: 1987
Location: southern Germany

Re: A 750 Sport from 1989

Post by paso750 »

he means the rim not the tire. With a 160 you`re using a 4,5" rim.
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ducinthebay
paso grand pooh-bah
Posts: 1323
Joined: Sat Sep 03, 2005 12:00 am
model: 750 Sport
year: 1990
Location: SF Bay Area

Re: A 750 Sport from 1989

Post by ducinthebay »

Yes, I was referring to the rim width. With a 4.5" rim, you can run a 150 comfortably. A lot of supermoto guys run 150's.

Cheers,
Duc in the Bay
1990 750 Sport x2-Rosso Blanko (900ss copy) & Nuovo Nudo (Scrambler project)
1991 907 -mostly stock
2002 ST4s - Lots of mods.
L Nino
Posts: 5
Joined: Fri May 14, 2010 10:27 am
model: 750 Sport
year: 1989
Location: Belgium

Re: A 750 Sport from 1989

Post by L Nino »

Thank you guys. I think a 150 would be great, although with a 160 the bike is already very agile (more than my previous bike, a 900SS from 1993, which had a 180 as far as I can remember). I'll have to change the rear tire one of these days, so the information will be useful.

Ducinthebay, you adopted these carb settings :

"36 PHM Dellortos with 2into1 exhaust
160/162 main (richer in back)
60 pilot
265 atomizer
K5 needle in middle postion
60/4 slide"

Have you tried other formulas with your D'll'Ortos 36 ? Do you consider these settings OK with any type of exhausts or good only with your 2-in-1? The Bos I have must be more open than the stock ones.

Cheers,

L Nino
User avatar
ducinthebay
paso grand pooh-bah
Posts: 1323
Joined: Sat Sep 03, 2005 12:00 am
model: 750 Sport
year: 1990
Location: SF Bay Area

Re: A 750 Sport from 1989

Post by ducinthebay »

Yes, that is the jetting that I'm running currently. I'm not entirely happy with the jetting though. I bought some other slides to try different settings. I have a full set of jets already, and a few needles to select from. I have an article from 1990 about hopping up the Sport, and will scan it an post it here. It had all the settings for a set of 36 Dellortos. I have two Sports, and one definitely runs better than the other. I haven't quite figured out why yet, but I suspect that the slower one does not have proper spark advance, but a full comparison of the carbs should also be done. I have also added a rubber elbow on the back of the carb and attached the air cleaner up above the carb in the space under the tank left by the old air box. Helps at idle, low speed and midrange.

I too will go to a 4.5 wheel and a 160 rear tire as soon as I can find a white one. Seems all the white rims were 5.5.

Cheers,
Duc in the Bay
1990 750 Sport x2-Rosso Blanko (900ss copy) & Nuovo Nudo (Scrambler project)
1991 907 -mostly stock
2002 ST4s - Lots of mods.
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