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.

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.

Looks good & welcome to this Forum!

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,

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.

he means the rim not the tire. With a 160 you`re using a 4,5" rim.

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,

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

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,