1993, 900ss, anyone using Mikuni TM 40-6 carbs - Page 2 - Ducati.ms - The Ultimate Ducati Forum
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post #11 of 43 (permalink) Old Mar 20th, 2019, 7:40 am
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Interesting. If I can find a set cheap Iíll get them and play around with the throttle issues.

'96 Ducati SS900CR, '07 S4RS, '06 Busa, '77 Bonny,
'00 Superglide, '85 Sportster, '78 SR500
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post #12 of 43 (permalink) Old Mar 20th, 2019, 7:42 am Thread Starter
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I found them last week on amazon for as little as 208 usd each
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post #13 of 43 (permalink) Old Mar 20th, 2019, 8:54 am
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Bank of fcr's appear to be more midrange
split singles appear to be more top end.

Banks are easier to maintain as sync almost never changes, splits will go out of sync rapidly if you use the idle whips.
Splits look cooler (IMHO)

my track bike has splits and my street bike has a bank. Application is important to think through first as they are not cheap so do your home work and be honest in where you will be riding (rpms). A common mistake is to build a bike for how you think will make the most power even if you seldom ride there. I will also throw another wrench out in that I would chose 39's 90% of the time over 41's based on acceleration (part throttle accelerations) over again a peak number. I have a couple posts on just this question not long ago complete with dyno graphs for comparison.

What will be the use of the bike?
what rpms will you use the bike at?
what are you looking for out of the carbs?

A built 985 will want a different carb than a stock 900 so do not buy more than you need unless you have future plans to spend more money.
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post #14 of 43 (permalink) Old Mar 20th, 2019, 8:57 am
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in my race days most people were faster on cv's then those very hard to control mikuni flatslids. i wouldnt wast my time on them.
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post #15 of 43 (permalink) Old Mar 20th, 2019, 9:02 am
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Ok after reading a bit...ive decided to up my budget and go for something i know that will work.
Fcr 41s it will be. Then there is still a choice to be made......
Split or banked. Ive read that split is more difficult to tune? And its more expensive because of intake manifolds and airfilters.

What would be your recomendations?
whatever are the cheapest.lots of second handies floating around. never had a problem tuning either. linked carb are a little harder to get to the mixture screws.
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post #16 of 43 (permalink) Old Mar 20th, 2019, 9:12 am Thread Starter
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I will be using the bike 99% for road use. Not really sure where i use the engine most rev wise. I think its from halfway to 90% revs. Accelerating out of bends often WOT. Top speed isnt my goal. I like to ride curved roads in a sporty way but dont care about insane topspeed.
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post #17 of 43 (permalink) Old Mar 20th, 2019, 9:16 am Thread Starter
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What would be your recomendations?[/quote]
whatever are the cheapest.lots of second handies floating around. never had a problem tuning either. linked carb are a little harder to get to the mixture screws.[/QUOTE]

In all honesty...i dont find used sets atm. But maybe i must use some patience.

I love the looks of a split set, but if it would be better for my use to use banked then i would do that.

Right now the only engine mod is high comp JE pistons but who knows what the future brings.
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post #18 of 43 (permalink) Old Mar 20th, 2019, 11:46 am
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Most 900 supersports live in the 5000-7000rpm band and spend less time 7000-9000rpm. If you plan on spending time below 7500 then the bank would probably be better. If you want to try and make it a additional 1500rpm then you likely need splits, and cams .. and porting. The 2-valve heads really do not make much above 8000 unless you build it that way (it isnt in its nature) as the head design is not designed for high rpms. Of course 8000rpms is high rpms compared to some motors.


Run one is a long manifold 900 monster vs a short manifold 900ss. the SS with short manifold makes and carries its power higher and the long manifold makes its power earlier and stops making power sooner. Run 2 is a experiment with 2 800 monsters. 1 is a s2r800 with short manifolds and injection, the other carbureted with stock cv carbs and long manifolds see if you can guess which is which?

Depending on what rpms you ride at the power should be where it will do you the most good. If you have short manifolds and build a highrpm bike you will likely be slower than a stock bike at lower rpms. This is why it is important to first decide on what rpm band you are going to play in and then you need to ride it that way.
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post #19 of 43 (permalink) Old Mar 20th, 2019, 11:59 am Thread Starter
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I actually like the power to be not all in the above rev range. Headwork cams etc is also expensive and i think with only fcrs and high comps the bike is good for my needs.
So that would suggest banked with longer inlets would be the better choice?!
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post #20 of 43 (permalink) Old Mar 20th, 2019, 3:46 pm
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Personally I donít think fcrís on a near stock motor is not good bang for bucks. Lighten the flywheel and shorten the gearing would be my first mod for a street bike. And maybe a shorter throttle.
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