750 Sport cylinder replacement

discussion about the 750 Sport and '89/'90 900SS, which share many mechanicals with the Paso series
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Desmo Tutu
Posts: 19
Joined: Mon Oct 24, 2016 8:21 am
model: 750 Sport
year: 1990
Location: Norway

750 Sport cylinder replacement

Post by Desmo Tutu »

Need some advice from the forum .
Just got hold of a 1990 750 Sport (could be earlier model, frame# ZDM750S750043 seems low to me).
The front cylinder has a ridge near the top, and evidence of exhaust blowing past the rings.
So i need at least the front cylinder. The piston looks OK but haven't checked the tolerances yet.

Is it only the 750 Sport & Paso cylinders that will fit, or can I also use the later 750 SS/Monster cylinders and pistons?
Are there modifications needed if I use later cylinders?

Are there differences in piston weights on the later model so that I have to change both cylinders and pistons to keep the balance if I go that route?
Desmo Tutu
Posts: 19
Joined: Mon Oct 24, 2016 8:21 am
model: 750 Sport
year: 1990
Location: Norway

Re: 750 Sport cylinder replacement

Post by Desmo Tutu »

Has no-one on the forum experience whit this?
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Derek
paso grand pooh-bah
Posts: 768
Joined: Thu Nov 03, 2011 10:13 am
model: 907 I.E.
year: 1994
Location: Scotland

Re: 750 Sport cylinder replacement

Post by Derek »

As far as I'm aware the barrels and pistons from the 750SS or 750 Monster should fit. I would not be surprised if the SS/Monster pistons are a different weight from your 750 Sport as there were a few changes to the pistons around this time. I have seen two different pistons for the 600SS from different years. You would be better to change the barrels and pistons as a pair if possible then, not only will the piston weights be the same but, assuming the both came from the same donor engine, the wear in each would be same so hopefully each cylinder would have similar compression pressures.
1994 907ie
2017 Supersport 939
2015 Scrambler Classic
1982 Pantah 500SL (now sold)


Scotland
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ir_joep
Posts: 107
Joined: Sun Jul 26, 2009 7:35 pm
model: 750 Sport
year: 1989
Location: Haarlem, The Netherlands

Re: 750 Sport cylinder replacement

Post by ir_joep »

Hi,

Please note that Some early 750 ss were stricktly air cooled and not oil/aircooled as sports and pasos.

There were Some changes in the combustion chambers as well. Possibly leading to different pistons?

KR Joep
Desmo Tutu
Posts: 19
Joined: Mon Oct 24, 2016 8:21 am
model: 750 Sport
year: 1990
Location: Norway

Re: 750 Sport cylinder replacement

Post by Desmo Tutu »

My cylinders are just air cooled, not oil/air.
User avatar
Derek
paso grand pooh-bah
Posts: 768
Joined: Thu Nov 03, 2011 10:13 am
model: 907 I.E.
year: 1994
Location: Scotland

Re: 750 Sport cylinder replacement

Post by Derek »

According to Ian Falloon in his "Ducati Belt Drive Two-Valve Twins Restoration and Modification":
The 750 Sport was released in June 1988 and used a 750 Paso engine. For 1989 "... while the engine was largely unchanged, some 750 Sports now incorporated an air-oil cooling system where the jackets around the bore liners allowed additional oil to circulate. While not uniform on 1989 750-cc engines, it would feature on all later 750-cc engines"
So it seems that for 1989 some were air-oil cooled and some were simply air-cooled. Presumably the air-oil cooled cylinders will have external oil lines that the SS and Monsters have.
1994 907ie
2017 Supersport 939
2015 Scrambler Classic
1982 Pantah 500SL (now sold)


Scotland
Desmo Tutu
Posts: 19
Joined: Mon Oct 24, 2016 8:21 am
model: 750 Sport
year: 1990
Location: Norway

Re: 750 Sport cylinder replacement

Post by Desmo Tutu »

Anyone on the forum that have a cylinder for sale?
I'm interested in whatever you have that fits my enige, if its only the front cylinder, with or without piston, both front and rear etc. Just send me a PM and lets see if we can make a deal. Thanks.
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