Mikuni lean spot & pod filter #'s

[RADDUCK]

The 4245ST was indeed too large so I returned them and have the 4229ST coming in the mail. I'm sure they can be stretched a bit to fit with some soapy water a little heat from the heat gun. Did not see any instructions with these UNI filters. I assume they will need to be oiled sparingly with air filter oil just like the ones I use on my XR650R? I called Dynojet yesterday and order 2x YJ124 and 2x YJ128 plus 4 o-rings. I'm going to start with the Stage 1 YJ124 jets/ needles position 4 / mixture screws 2 turns and go from there.

Here are a few pictures of bike, the woman, and Frankenstein Airbox that came with the used motor

[paso750]

5mm is quite a bit to stretch. Couldn`t you have them order others ?
I had mine sent over from Australia but they arrived pretty fast with the help of some other member.
That airbox makes me speechless. If you didn`t say it was your airbox I would `ve bet it was some sort of rodent trap
Normally new filters are already oiled. Some guys simply use WD40 put I think special airfilter oil like the one from K&N is better as it`s stickier.

G.

[Mc tool]

you can actually get a water soluable air filter oil ( synlube ), which means you can just run the filter under a warm water flow instead of using petrol ( or whatever ) to clean.
That air box sure is a work of art. I've seen pictures painted by elephants before but this is the 1st " sculpture by monkeys " , although I would have to say making something like that isnt easy. I have been looking at some of the larger tupperware / click clack type containers to see if one couldnt be modified/adapted , but I dunno if the plastic would be fuel proof

[RADDUCK]

So my airbox resembles a "Rodent trap" and a "sculpture by monkeys"... I laughed outloud. I can't take credit for its unique shade-tree, alcohol induced design characteristics but the tape, weatherstripping, and orange silicone to seal up the many potential leaks were all my doing. I Guess its all for Nought with that big chunk that's now missing from the bottom of it. At least that will improve the flow for the Stage 6 closed circut racing application... For $19.95 I can fashion another just like it if you know anyone interested.

[paso750]

I love the combination of cardboard, silicone and rivets

[RADDUCK]

That's where it gets interesting. It only looks like cardboard, I believe its aluminum siding from a housing project gone wrong or a mobile home.

[RADDUCK]

Update - Got everything installed about 2 weeks back. Went with the Uni-Filter Pods (4229ST perfect fit), Dynojet stage 1 kit, Needles on position 4 from the top, 2 turns out on the Mixture screws and the YJ124 main jets. Forgot to hook up the choke and didn't realize it until I tried to fire it up for a test ride. Lots of cranking, no love. When it did fire up it wouldn't idle, lots of popping and backfiring. Went for a short test ride anyways and it ran terrible. Nice and smooth at about 4K but definitely lean right off idle, bucking and hesitation. Weaker WOT than with the stock jetting. Parked it for the night. Next morning turned the mixture screws to 3.5 turns out and it was a whole different machine, idles again starts w/o choke. Still slight hesitation off idle when cold and WOT not as strong as previously. Pulled carbs and installed larger stage 2 YJ128 main jets, remembered to hook up the choke this time. Best its ever run. Strong and beefy, WOT stronger than with stock jetting, smoother running characteristics throughout the entire range. Easily pull away from a stoplight just above idle even with a passenger. Still get some popping on closed throttle when decellerating. Turned the mixture screws to 4 turns out definite improvment, still the occasional pop. Spoke to Owner at DesMoto, a great Ducati only tuning shop in San Francisco, (Admired a beautiful Paul Smart 1000). Apparently 5 turns is the maximum range for the mixture screws before they can vibrate and fall out. I'm at 4 turns now and may try to go a little richer yet. If no improvment I will raise the needles 1 notch next time I have the panels off and go back to 3.5. All in all a much better running machine. Not sure I'm in love with the honk from the pod filters. Deeper throatier sound with the rat-trap air box. Thanks again for the hook up with the Dynojet kit Gerhard. Happy New Year!

[Mc tool]

That all sounds a bit familiar.
once upon a time in a land far away ( is too !! ) I had the carbs on my ( now defunct ) 900SS I notices that all the jets were not what the book said they should be , AND I had to unscrew my idles out 6 turns to get reasonable low end performance ( this was all before I'd ever heard of a dynajet kit , which I now suspect I have )( no top on air box ). Anyhow I use my vacuum guage to set idle screw, I set it at max vacuum and then open screw 1/8 turn, which , as I say left me 6 turns out , which bothered me but then I piled it into the side of a car at 80mph and that solved the problem..... sort of, more of a priority thing really , but if your interested I could have a look at these jets and let you know what I have


Somebody else has used the same ( racing ) air box designer as you, note the " open weave " filter material

[paso750]

that racing airbox is awesome

Radduck, you`re welcome. Seems you`re on a good way. If I remember well I had read somewhere that 4 turns and more indicate an incorrect jetsize. Someone else will know better.

Each time you remove the membrane covers be careful not to lose the small o-rings on the bottom. Also in case the adjusting screws ever should come out note there`s a very (very!) small washer infront of the spring.

G.

[pepe rull]

hello from Spain-Andalucia. I own a Ducati 750 Paso year bdst 1988.Decidi put the Mikuni 38 with his monster collectors for 750 and 140 in high gum and low, put a K & N RU-2970 is double filter, and the problem is that the bike but does well in low ... when it gets to 120 -130 km / h, stops accelerating and is "waiting" for I hasten the maximum, because it does not go up from there, this ruling is huge and I think it may be due to excess air to the carburetors (filter?) Live like your at sea level, anyone know who might make?because it is slow, inefficient and that ruling becomes dangerous. There are some changes that you say here? anything I can do to have her back in the carretera.Gracias from Almeria, Andalucia-Spain

[paso750]

Hi pepe, is that an automatic Google translation ? It may be better if you post in spanish.
If your acceleration suddenly stops at 130km/h you`re sure running very lean. I had exactly the same reaction on my Gilera 600 when I mounted an open sports exhaust without rejetting the carb.
Is your Paso original or are there any modifications like a different exhaust and did you synchronize the Mikuni ?

[pepe rull]

Hola,si,era el translator,yo hablo algo de ingles pero..no demasiado.
Mi paso tiene un sistema de escape identico al de la foto en el que sale tu chica...un "GIO C.A. MOTO"
Tmabien como te dije unos mikuni bdst 38 nuevos(comprados en tienda ducati,pero con los surtidores para 600 monster,aunque ya tiene puestos los que recomiendan, 140...etc.
Te estaria agradecido si me dices que hacer...porque tras hacer que funcione bien el motor,me gustaria mejorarle los frenos...pero...quiero ir paso a paso(nunca mejor dicho)
Muchas gracias de nuevo y espero tu respuesta.

[paso750]

that`s not my bike above
If you have a Mikuni from a 600 Monster and just put it on the Paso that explains a lot.
Someone said that the passage ways in a Mikuni from a 600 Duc are smaller than the ones in a Mikuni from a 750/900.
I don`t know about that but the standard jetting is different on 600, 750 and 900 engines.

750SS:
main jet: 140
main air jet: 70
needle jet: Y-6
Jet needle: 5C19 - 3rd notch from top
Pilot jet: 37,5
Pilot air jet: 60/1.4

900SS:
main jet: 140
main air jet: 70
needle jet: Y-2
Jet needle: 5C19 - 4th notch from top
Pilot jet: 42,5
Pilot air jet: 60/1.4

M600:
main jet: 132,5
main air jet: 70
needle jet: Y-2
Jet needle: 5CJ1 - 3rd notch from top
Pilot jet: 37,5
Pilot air jet: ?

You will have to remove your Mikuni and disassemble it to check the complete jetting you currently have.
To get to the needle jet you remove the nut marked red and push it out (with the grey plastic part)




With the K&N filter you`re using and the Gio.Ca.Moto 2in1 exhaust neither the 750 nor the 900SS jetting will be completely right and can only serve as a starting point. I guess I`d use the 900SS jetting for reference in your case and go from there, so with a larger main and pilot jet and new jet needles.

Important to prevent leak air of course is to use good rubber boots (the connections between the Mikuni and the carburettor manifolds), to use paper gaskets between the carb manifolds and the cylinder heads and to close the the hose nipple connections on your carb manifolds if these are not used (with a small screw and copper washer).

G.

[pepe rull]

that`s not my bike above
If you have a Mikuni from a 600 Monster and just put it on the Paso that explains a lot.
Someone said that the passage ways in a Mikuni from a 600 Duc are smaller than the ones in a Mikuni from a 750/900.
I don`t know about that but the standard jetting is different on 600, 750 and 900 engines.

750SS:
main jet: 140
main air jet: 70
needle jet: Y-6
Jet needle: 5C19 - 3rd notch from top
Pilot jet: 37,5
Pilot air jet: 60/1.4

900SS:
main jet: 140
main air jet: 70
needle jet: Y-2
Jet needle: 5C19 - 4th notch from top
Pilot jet: 42,5
Pilot air jet: 60/1.4

M600:
main jet: 132,5
main air jet: 70
needle jet: Y-2
Jet needle: 5CJ1 - 3rd notch from top
Pilot jet: 37,5
Pilot air jet: ?

You will have to remove your Mikuni and disassemble it to check the complete jetting you currently have.
To get to the needle jet you remove the nut marked red and push it out (with the grey plastic part)
...

With the K&N filter you`re using and the Gio.Ca.Moto 2in1 exhaust neither the 750 nor the 900SS jetting will be completely right and can only serve as a starting point. I guess I`d use the 900SS jetting for reference in your case and go from there, so with a larger main and pilot jet and new jet needles.

Important to prevent leak air of course is to use good rubber boots (the connections between the Mikuni and the carburettor manifolds), to use paper gaskets between the carb manifolds and the cylinder heads and to close the the hose nipple connections on your carb manifolds if these are not used (with a small screw and copper washer).

G.

Muchas gracias,ya comprobe que si,que tare especificaciones de monster 600,le he cambiado como tu dices..para buscar las especificaciones de la 900,o sea:cambiar chicles y agujas(las agujas no las he cambiado,tengo unas 5cj y la 900 ha de llevar una 5c19 y su correspondiente emulsionador).
Crees que deberia ponerle todo dentro del carburador para que sea exacto al 900?(o sea,debere cambiar las agujas ademas de chicles y regularlo).
En cuanto a lo que son distintgos o no los distintos bdst de la 600,750,o 900....te dire q solo se diferencian en los chicles..agujas etc..o sea lo que se puede cambiar.
Te ruego que me digas que partes del carburador pondrias para ser cono el de la 900...y cuales dejarías(agugas y sus emulsionadores..etc)
He leido que la diferencia entre las agujas que tengo y las 5c19...es que una es de ángulo simple y la otra de ángulo doble...
Tu crees que mi paso va tan mal...solo por no cambiarle las agujas?
Te doy las gracias por tu información....es muy importante para mi,tube hace mucho tiempo un gravisimo accidente con mi moto y tras casi 20 años esperando ponerla en la carretera,,y ya funciona,pero no va bien como te explico y me encantaria poder hacerla funcionar con tu ayuda.

[pepe rull]

Hola de nuevo,ademas el "nedle jet" es el mismo en todos según los datos que me dices( Y2) por lo que debere solo cambiarle las agujas a unas 5c19...ya que supongo que el "Y2" es valido para ellas.
Tebgo una cuaestion que preguntarte...los "main air jet" y "pilot jet" cuales son exactamente..? me los señalas en el dibujo,por favor? realmente al desmontar el carburador,no todas las piezas tienen señalada su medida, llevan numeros de serie internos que no corresponden con la medida,asi que uso calibrador para medirlo..
Pero si me señalas en el dibujo esas partes me sera menos divicil comprobar sus medidas