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Discussion Starter #1
OK I purchased this very early 1991 900ss on May 17 2019, It sat for a week before I could touch it. The biggest issue was a typo on the title, this was solved by registering the bike in Vermont that took about 3 weeks, This 900ss had not been ridden since 2002 so I had to do a few things--Here is the list--New Tires, new battery, new spark plugs, new oil & filter, brake & clutch flush, new belts, new tail light lens, new left combo switch, new fuel pump & fuel filter, clean & reline fuel tank (w/ POR 15) new fuel lines, complete carb rebuild w/ factory pro stage 1 jet kit, things that I didnt have to do but wanted-seat cowling, Carbon Tech high exhaust, K&N air filter-New speedo back to KM-(speedo had been changed to mph when the bike came to the U.S.only had 98m on it). Front Carbon Fiber mudguard from an SP. found 1991 original owners manual. ordered high pipe mounts & front frame brace from BBBFabrications, Cleaned and greased every electrical connection on the bike. This journey has taken about 7 weeks now-the amount of time I spend with tools in hand-about 12-15 hours Total $$ spent including the price of the bike-$2700.00 It started today for the first time in 17 years-tomorrow I finish-- whats left synch and adjust carbs put the 2 side fairings & seat on and go for a ride-tomorrows work about 30 min. when the exhaust hangers & frame brace arrive that should take about 30 min max to install, then it's time to ride and enjoy this very early production 91 900ss. I have been looking for one of these for about 7 years I had to find the right one at the right price and I think I did. Pictures will come probably within a few days. I want to thank everyone here that has helped me with advice and steering me in the right direction, Also I want to thank Sebastion at MelilliMoto he is close to me and he knows Duc's Like I know BMW's we help each other all the time.
 

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Discussion Starter #2
OK I got the carb sync done -Rode the bike everything seems really good with only 1 [email protected] around 3K rpm the seems to stumble a bit and maybe load up-idle is good @ 1050rpm, under acceleration it is perfect-the only issue is the loading up/ stumble @ 3K--again I dont know these bikes very well but my first thought is to drop the slide needles 1 position. -Does that sound about right or someone that knows these bikes better have another suggestion. Any help is appreciated. Thanks in advance
 

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Talked to the tech at Factory Pro this afternoon, told him what was going on. He told me to play with the air/fuel screw turn it out 1 turn see it gets better or worse, if it was worse-turn it in 2 turns-that would put me 1 turn in from where it was before I turned it 1 turn out--see if it gets better--if so turn it in 1 more turn--see what happens, So I did wound up going in on the screw it got better but still stumbling-I had the 40 pilot jet in that came with the kit--He said put the stock 37.5 pilot jets then play with the fuel screw-most likely turn it out about 2 turns to start and it should clean up--So now waiting for new 37.5 pilots. Hopefully this will clean it up and I'll be riding it --I did put about 12 km on it today just testing, Off the pilot it pulls like a freight train and is smooth. This is going to be fun
 

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Discussion Starter #5
Well when you have a 5300 square foot full service shop it helps alot lol--I have 6 lifts & 4 restoration benches, Ducati's are new to me--But I have been servicing & restoring BMW's for 35 + years so even though I have done very little on Duc's -mechanically it's not that big a deal to me --But it's the little crap that I am not used to that I have to play with and ask for help.
 

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Discussion Starter #7
I think 3000rpm is considered Idle speed on mine. never tried using it muck under 3500rpm as i have a 50cc scooter for slow work.
I normally am running above 3500 rpm as well but it just happens to be right where this bike runs around the small town and streets I have to travel, I have stock gearing on this bike I know I could change that but if the jets solve the issue it's a quick easy fix, If I were running 90 mph and up all the time I probably would not touch it but I just want it to be right so I can enjoy it.
 

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When I first bought my carby I thought that’s the way it was, they just didn’t like it below 3000 rpm. After playing with the carbs, Factory Pro components, I was able to get mine to run smoothly almost down to idle speed . So it can be done, if you care to play with it. I was at a RV park for an extended stay and it had a 10 mph speed limit. I didn’t feel like aggravating everyone each time I went for a ride, and maintaining 10 mph was impossible. The alternative was to tune the carbs well.
 

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I have one of each of these descriptions, one lumpy but firm below 3000rpm's with FCR 41's / 39 tooth rear and the other stock carb I just put in a 41 tooth rear so it can spin the 4,000rpm minimum on a light flywheel it wants. Like an old married couple, I just stopped fighting it.
 

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Im really confused here. I guess the 750ss is different? I actually have a set of Mikuni's off of a 900ss with the stock jet kit for the 750ss. I can slow my idle as low as 900rpm (I have it at 1100). I have no hesitations up to redline. I am starting to feel lucky. Are the 900ss known to have hesitation/carb issues below 3000rpms?
 

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Discussion Starter #12
yes & adjusted float lvl as well-mains, needles & pilots
 

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Remember this is an internet forum so the differences in good driveability may be large as it is a perception. What one calls good another may call poor and both may be right, depends on your standards . I never said a 900 would not run okay at low rpm's just not its happy space, they run so much better a bit higher I do not care to lug the motor.

Gearing does make a large difference as does flywheel mass so different setups can create a different experience. Could a 900ss be set up to work well at 10mph? I am sure of it I would just not find the need to create such a bike myself as I feel there may be better bikes for that application. To each his own as you all know what your riding circumstances are, build to you riding enviroment and you will always be happier.
 

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Ducvet has been doing this stuff a long time as have many of us. Ducatis are not like other twins - they need to be ridden at a little higher RPM and in fact I've read and been told by factory Ducati techs that prolonged low RPM operation (which in a Ducatis case is considered lugging) can cause crank damage. Do yourself a favor and accelerate it up to 4000 RPM and dont shift up if it will drop you below about 3500 to 3750.. I'm not saying they cant be tuned to run below that, I'm just saying that in my experience they shouldn't be.
 

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I can feel just riding the thing it wants to be over 4,000 RPMs at least after 1st and maybe 2nd gear.
It's a singer. >:)

And the song is not about potatoes. :rolleyes:
 

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I can feel just riding the thing it wants to be over 4,000 RPMs at least after 1st and maybe 2nd gear.
It's a singer. >:)

And the song is not about potatoes. :rolleyes:
... puhtatuh puhtatuh puhtatuh puhtatuh puhtatuh puhtatuh .... varrrrooooommmbahhh!!! ..... puhtatuh puhtatuh puhtatuh puhtatuh puhtatuh puhtatuh ....

.... the Harley mating call ....




:grin2:
 

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Discussion Starter #17
I agree that they like to run over 4K -That I have no problem with, but to get to 4K you have to go thru 3K lol--and this bike right now stumbles like crazy and just feels like it is loading up -once past 3200 it smooths out nicely under acceleration -but even at say 4K once you hold the throttle at a neutral position just to maintain a given speed it still feels like it is loading up and stumbling--I just have to play with it a bit to get it sorted and find the sweet spot. But with what it doing right now it is just not usable for where I ride
 

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My stock carb bike is exactly this, so if you sort it out by all means share!

Edit: to get to this relatively satisfactory performance I went back to the stock airbox lid, put Db killer's in the exhaust on their 2nd quietest setting and fiddled excessively with the needle height and idle enrichment settings. All new needles on a zero mile NIB carb. Now after 1,200 miles on two sets of plugs with perfect looking burning I've accepted the low rpm performance although it does rush through the 2-3krpm's very quickly with a Nichols flywheel and a 41 tooth rear!

Could be a co-incidence but in the last week I've replaced the throttle cables and for a while the "surging, unevenness" at steady throttle was worse until I loosened the return throttle cable. Now while I can still hear and feel the steady throttle roughness below 5k, I can no longer see the variation in the tach. Slightly too tight throttle return cable amplified the unsteady issue.
 

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Discussion Starter #19
OK Guys It's done, Had to change the pilot jets back to 37.5 too her out for a test ride and all seems perfect-I just have to get used to this bike but she seems to pull like a freight train and only very minor stumble right off idle under load. But she runs great and I think she looks pretty damn good for a 28 year old bike. The only thing I need to do is get the correct decals for the tank, other then that I'm done-cost of this project including the bike I am into it for $ $2625.00. So I dont think I'm hurt on this at all
 

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