Being nasty to my 750 Sport

discussion about the 750 Sport and '89/'90 900SS, which share many mechanicals with the Paso series
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ducinthebay
paso grand pooh-bah
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model: 750 Sport
year: 1990
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Re: Being nasty to my 750 Sport

Post by ducinthebay »

Yeah, when I switched out the calipers on my Sport last year, they were spongy for a long time. I had new pads, so I figured they just needed to be bedded in better. But subsequent bleeding of the brakes made it better over time. Still not as hard hitting as they used to be, but plenty adequate.

Cheers, Phil
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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paso750
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Joined: Sun Jul 18, 2004 12:00 am
model: 750 Paso
year: 1987
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Re: Being nasty to my 750 Sport

Post by paso750 »

I hope you don`t mind if I come back to the speedometer drive. That`s something I`m keeping an eye on for a longer time as here in Germany a speedometer is allowed to show up to +7° deviation but -0%.
Which makes sense as a -x% deviation means you`re going faster than what you`re instruments are indicating.

Now putting some numbers behind that if you swap from a 130/60-16 to these tires you get the following deviations
130/70-16 -4% (hence you`re actually doing 100km/h when the instrument is showing 96)
120/70-17 -6%
120/60-17 -2%

Instruments usually show a bit more so if the negative deviation caused by a tire with a larger diameter is small this may equalize it. But of course only if you kept the original speedometer drive (ratio).

As this concerns me, too I`ve collected some info about speedometer drives that look similar.
These are the ones from different bevel drive Ducs, numerous Guzzi models and a Morini/Benelli.
Disregarding if these are for 17, 19 or 20mm axles the ratios found are 20/10, 20/11, 21/9, 21/11, 23/11, 24/11 and 25/9.
I could not find any info about the ratios from Cagiva/Aprilia 125 drives or the ones from newer Ducs with the large plastic drives.

Now someone correct me if I`m wrong !!!

A ratio of originally 21/12 means the wheel turns 21x to turn the speedometer cable 12x.
Now doing some math a 20/11 deviates from a 21/12 drive by -3,75% and a 25/9 by -37% (!), correct ?
If that adds to the deviation caused by a different tire size the speedometer could be -6% to -43% off (depending on tire and speedometer drive combination) which leads to the conclusion that it`s always better to keep the original drive (and to weld on a longer tongue if necessary), modify one from a SS and/or to use a digital bicycle speedometer or a GPS.

sidenote: I didn`t calculate it but if it`s right what I found the K value of the speedometer is 1,4 on Ducatis which means that 1.400 turns of the speedometer cable translate in 1km on the odometer. Different tire sizes and speedometer drives will falsify that as well.

Again, let me know if my thinking is right or wrong. Also are there any companies that make or sell inline gear ratio adapters (with metric threads) ?

G.
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bmw851
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Re: Being nasty to my 750 Sport

Post by bmw851 »

That's way to much detail for me G. :shock:

Think I may borrow my son's Tom Tom GPS tracker and strap it to the bike, really hadn't thought of that one, and it is so obvious a solution. :banghead:

Cheers

Peter
So long, and thanks for all the fish...............

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bmw851
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Re: Being nasty to my 750 Sport

Post by bmw851 »

Finally got the last piece of the puzzle back from the Engineering Shop.
Original Adapter Plate.jpg
Original Adapter Plate.jpg (84.44 KiB) Viewed 6890 times
The hand shaped one’s worked well enough but offended my sense of aesthetics
Revised Adapter Plates.jpg
Revised Adapter Plates.jpg (32 KiB) Viewed 6890 times
Drew these up in Autocad and had them made, very, very pleased with the way they turned out, (that was a story in itself as hadn't used Autocad in 3 or 4 years, amazing how quickly you forget stuff).
Revised Adapter Plate.jpg
Revised Adapter Plate.jpg (90.98 KiB) Viewed 6890 times
So this is the end result, may paint them silver at some stage to match the fork legs, but that's a Ron job.

Just need the weather to cooperate a little bit and can then go out and play.
So long, and thanks for all the fish...............

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ducinthebay
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Joined: Sat Sep 03, 2005 12:00 am
model: 750 Sport
year: 1990
Location: SF Bay Area

Re: Being nasty to my 750 Sport

Post by ducinthebay »

Certainly look substantial enough. Should do the trick till some 4 pots show up for Christmas.

Cheers, Phil
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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paso750
paso grand pooh-bah
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Joined: Sun Jul 18, 2004 12:00 am
model: 750 Paso
year: 1987
Location: southern Germany

Re: Being nasty to my 750 Sport

Post by paso750 »

the first moment I was wondering where the pictures of the new adapters were ;)
I thought you`d make them a little different i.e. by recessing or cutting out the front section.
I`d paint them black.

Noone have an input regarding my last speedometer drive post ?

G.
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bmw851
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Re: Being nasty to my 750 Sport

Post by bmw851 »

G, your correct could have drawn them up and made them better looking, but am paranoid about having them as solid as can be, and given what the bike is going to be used for, well, went with the retain as much meat as possible principle. :thumbup:

Cheers

Peter

And Xmas will be about right Phil :lol:
So long, and thanks for all the fish...............

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bmw851
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Re: Being nasty to my 750 Sport

Post by bmw851 »

Have finally gotten out today for my first decent run on the Sport all converted so to speak.

I cannot believe the difference this conversion has made to the bike, it is like riding a 250 with some serious mumbo, it still has that very classic Ducati feel in that once committed to a corner that’s pretty much it, but it's actually not, it can now change line mid corner, so a lot more more room for error than with the 16’s and much more chuckable.

This thing is a hoot.
Last edited by bmw851 on Fri May 10, 2013 8:06 am, edited 1 time in total.
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bmw851
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Re: Being nasty to my 750 Sport

Post by bmw851 »

Old fart on an old tart, sounds a bit rude me thinks, but true, apologies to the “caring understanding nineties types” out there.
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Finally got the old girl out for another (absolute spur of the moment decision, sorry Andrew next time) track day at Eastern Creek, and finally a run on the 17’s, actually got in 2 full sessions before torrential downpours ended the days proceeding’s. (That equates to nearly all of a whole 14 laps on the old GP circuit)

What did one learn?

Do make sure your tyre warmers will actually fit before the day, particularly the front :mad: .

Do scrub in your grooved slicks before the day :banghead: .

Don’t drop your tyre pressures to counter lack of tyre warmers, which will then encourage lurid rear end slides from your Ducati because of under inflation, it’s just plain silly :choo: .

Don’t be a big nancy boy (again apologies to the 90’s types) and take 2 sessions to start getting into it :wacko: .

Do believe your Doctors when they tell you that riding with a couple of fractured vertebrae and a not happy collar bone/elbow and wrist may be painful and cause more damage, and did. (A long sad and tawdry story, part of why a chap has been so quiet on the site of late, but I’m over it, Hamish the door is open go for it and it had better be good :lol: )

Do ride as many laps as you can, whilst taking as much Ibuprofen as your stomach can handle. :smoke:

Do out brake people into corners. (Bastard)

Do be a SAB and ride around the outside of guys with their knee down and think their last name is Marquez, only because you can. (Smart Arse Bastard)

Do be a mongrel and out brake same said people when they make you look like your sitting still while doing 200 Kph down the straight, and of course block them mid corner and then make ‘em work for it. (Absolute Smart Arse Bastard)

Do accept the fact that there are some much, much more seriously faster people then you out on track, and get out of their way with as much style and graciousness as you can.(Not so smart arse bastard after all) :oops:

Yes a chap had some serious fun, and was the $2000 to convert worth it, hmmm, I’ll need another track day then let you know……………….. :thumbup:

Cheers

A very sore, but worth it :beer: .

Peter
Last edited by bmw851 on Thu Dec 05, 2013 8:56 am, edited 1 time in total.
So long, and thanks for all the fish...............

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bmw851
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Re: Being nasty to my 750 Sport

Post by bmw851 »

Couldn't help myself and took the old girl out for another spin at Eastern Creek.

Did you know Paddy thought Murphy was an optimist.

Yes it rained yet again, grooved slicks and a wet race track, and aside from being a riding ability challenge, was at the end of the day a fair bit of fun, now that is sad.

Oh well, we're really coming into summer now, so next time for sure......................
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So long, and thanks for all the fish...............

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Andrew2
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Joined: Thu Oct 27, 2011 7:47 am
model: 750 Sport
year: 1988
Location: Wollongong,Australia

Re: Being nasty to my 750 Sport

Post by Andrew2 »

That's why I did'nt go Pete :dunno:

Cheers
Andrew
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bmw851
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Re: Being nasty to my 750 Sport

Post by bmw851 »

Andrew2 wrote:That's why I did'nt go Pete :dunno:

Cheers
Andrew
Next time then, and bring the SS :D

Cheers

Peter
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Mc tool
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model: 906 Paso
year: 1990
Location: Newzealand

Re: Being nasty to my 750 Sport

Post by Mc tool »

bmw851 wrote: Hamish the door is open go for it and it had better be good :lol: )

Peter
Yeah , broken this , bent that and one of them that don't work anymore, know the feeling ( no pun intended :) ) but we still do it. Ive been back on my Guzzi ,( even got chased by the cops .... so things really are getting back to normal :D .... no brake light ... got a warning :) ) . Going racing, Ive dreamed of it for years but never got my shit together ,I have friends that race , the Mrs is keen ( I think she wants to hold my umbrella on the starting grid :D ) so no excuses . Why is it that now , probly the worst time in my life to ever consider starting racing ,that I want to do it more than ever . :dunno: :dunno: , but anyhow the bike does look good Peter
Hamish
I wish I was young again............Id be heaps smarter than last time
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bmw851
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Re: Being nasty to my 750 Sport

Post by bmw851 »

Mate, you don't have that much left to break, go for it :lol: :lol: :lol:

A2's ribs are pretty much healed, I expect to see him out there soonish :-P

We could start a Trans Tasman Series for old farts over 50 with a zimmer frame as the trohpy :beer:

If I asked my wife to be a umbrella girl, think I would have lot of trouble walking with it shoved up my Arrrrrrr, enough of that now :drunk:

Keep getting well :D

Cheers

Peter
So long, and thanks for all the fish...............

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bmw851
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Re: Being nasty to my 750 Sport

Post by bmw851 »

Track Day coming up on Friday, I'll be in the geriatric's group.

Woo as they say Whoo :truck:
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