All Mikuni converters - help please

[Mustang505]

Hi Guys
need some help here. In the process fitting a pair of the 38mm Mikunis off a 900 monster to my 750 sport rebuild. I managed to source inlet manifolds also off a monster (i'm told). However after mounting them the inlets are not square ie. if i mount the carbs they are not square with the frame. One inlet is 14mm closer to the battery than the other. I'll post some pics if what I'm saying is unclear.
Are inlet manifolds off mikuni carbed bikes a identical pair? Or is each different? My two are identical and could be fitted to either cylinder.

Cheers Clive

[Fraser]

Clive,

Don't worry, that's how they are; "identical but different". My Mikunis are not parallel, but at about 20 deg angle.
Cheers,
Fraser.

[Mustang505]

Thanks Fraser
Yep that's it about a 20 deg angle.

[paso750]

the reason is your inlet manifolds come from a 900cc Duc and not from a 750. Due do the slightly higher cylinders the manifolds are longer so when mounted on a 750 engine the carb will stand crooked.
And then yes, the front and the rear cylinder inlet manifold are not 100% the same. By swapping them there will be a change in position but that is very small.

G.

[Mustang505]

Thanks for that G
I did think of that as a reason but then surely then the heights would be different as well, but they are not. Inlets are perfectly level in relation to the ground - just squew on the horizontal plane.

[carlopalmas]

let me know how it goes... i had the worst experiences when the 38mm mikunis were mounted on my bike... the float bowl was always overwhelmed by the fuel pump so the bike would not de-accelerate when i would roll off the throtle... you know like when you go into a curve.

the fuel pressure regulator may take care of this... if you haven't already you may want to install and check what the ideal pressure is...

please let me know how this all works... always looking to improve on the webers

Carlo

[paso750]

a fuel pressure regulator is not necessary. Be sure you have the Y connector with the return line to the tank in the fuel line to the Mikunis.

[Foxtee]

Are these photos any help

[ducinthebay]

Looks good so far. I would add some rubber elbows between the aircleaners and the carbs. First it acts as a manifold and improves flow at low rpms. Second, you may not have enough room under that tank for those tall aircleaners as they are. To connect the air cleaner to the elbows, you will need a small section of thin wall pipe. I found some 2" stainless that worked well. You will need a total of 6 hose clamps.

Are you running a jet kit in those, or are they stock?


Cheers,

[Foxtee]

Carbs came off a Paso being ¨parted out¨ on ebay a few weeks ago ,put them on and she fired up first time.
Had a few probs with an old relay putting 12v to the coil but running well now.
Taking it to get a warrant of fitness tomorrow, then a good ride to see how it goes before checking the jetting. I´ll check out making some intake manifolds but the foam cleaners sit under the tank quite well at the moment.

[ducinthebay]

I see that you blocked off the vacuum lines. Do you have a Magnet Marelli Digiplex computer or are you running the Kukosan ignition? I know that the Marelli has a vacuum input, (I'm assuming its for timing advance) Does the Kukosan have a vacuum input?

Cheers,
Phil

[paso750]

Does the Kukosan have a vacuum input?

no