Hola, os escribo en español porque creo que sera mas facil traducir que escribir yo mal en ingles.
Tengo una ducati paso 750 años 88..y le compre unos mikuni buevos de los que equipaban las ultimas ducati monster...compre los chicles y los difusores recomendados para la ducati paso en las tablas publicadas en esta pagina.
Funciona bien..arranca..etc...pero no puede subir a mas de 120 km/h ni en 4ª ni en 5ª velocidad...no anda mas.
Me podreis ayudar y decirme que hacer con ella?
Muchas gracias

To me this sounds like a tuning issue at high load, large throttle which lots of people have commented on the forum.

have you read the tech article - viewtopic.php?f=1&t=705 (go down the page to the mikuni section) which will help you work out what you have and what jets you might need.

Hi Pepe,

https://translate.google.com/m/translate

This might help. ....

first of all there are numerous questions to answer:
- what is the complete and exact jetting of your Mikuni (from which Monster did it come from?)
- what exhaust are you using?
- what airfilter or airbox setup are you using?
- what spark plugs are installed?

While throttling from the carb running too rich can cause bad acceleration and limit speed it`s more likely it`s running too lean in which case you shouldn`t use the bike until the jetting is corrected. How do the sparkplugs look like? Are they black/wet or are there signs of them getting too hot? How does engine temperature behave and do the headers show any signs of discolouration?
Without knowing the answers to these questions one can only guess.

Hello, the mikuni are the originals for ducati, unused, with: main jet 140, air 70, needle jet. Y-6 - jet needle - 5c19 in 3th from top - pilot jet 40 - air - 60 / 1.4.
Gio ca Moto - scape ... and v & h in the air
It does not want to rise of revolutions ... and until there, it works apparently well.
The candles color cafe au lait and are not wet

what does "v & h in the air" mean?
Except to the pilot jets it`s the original 750SS jetting used on an engine with an aftermarket 2in1 exhaust and foam filters on the Mikuni (without an airbox)? It is definitely running lean.

hi,it means filter conic for the mikuni,without box
What is necesary to go well?
i think im near of it..near of the ok...but,,, already isnt well
tel me what can i do,,,please!!!

ok,ill restrict the air flow..and tell you if my bike go to....be well or not.
i havent my bike now here...but soon ill see if is ok or not this action

Restricting airflow is a good test to prove what seems obvious. But it`s just to verify, it`s not a solution.

Before you try other jets do move the clip of the needle from 3rd to 4th notch from top and see what difference that makes.

is not only a matter of Airflow, it could also be turbolence caused by the speed that is effecting the airflow

Airboxes are there for a reason, is not only to hold the filter , but also to create an enviroment of calm air.

I dont think removing it is a wise move, better having the carbs fitted with a modded airbox.

Years ago I was visiting a well known Italian tuner and I was puzzled about a mod they use to make to the 748SP, SPS & RS airboxes, basically they where putting a small diafram in front of the airbox openings so that the air entering had go around it and slow down a little and by douing this the turbolence would be lower. That little mod was worth 2BHP extra over a certain speed and RPM.

With this kind of problem it's always a good idea to make sure the carburetors are getting all the fuel they need at the bigger throttle openings.

Hello again, after getting my ducati Paso to work acceptably, began to fail, when I went from being dead, to get first gear and try to roll with it, began to fail and did not let up revolutions, was momentarily in a Cylinder. I have the impression that there is an electric fault that ends in a combustion fault.
What can it be now? I'm demoralized with my bike, I'll never get it to work well?