Mikuni jets

[Finnpaso]

Ok, Guys, who have tuned they Mikunis:

What size main jets i shall try???

Modificatios to 750 Paso: Open pod filters(just "like" K&N, but cheaper ones). Open exhaust pipes with 40 mm headers and i drive normally in "sea level"(about here +0-400meters). I have already Dynojet kit Stage 1. (european version) for 750SS.

I think, i have all other jets ok, but what main jets?

[eliatt]

Hi,
Try 140 to 142.5 at first.

[Finnpaso]

I think, those are "way too big", cause my Mikunis came with 142.5 and they were in 900 Elephant earlier and in Dynojet kit there is 124 and 128 jets! Have anybody tried 128??? Stage 1. is designed for stock airbox or w.stock airbox with K&N filter, but mine have free flow pod filters instead normal K&N. What can be difference between main jets, if little different air filters?

[paso750]

with open filters and exhaust I think 140 is a good start off. Whatever was on an Elephant, both 750 and 900 Supersport used 140 main jets from stock. Ducs need to run a little bit on the rich side.

G.

[Finnpaso]

What size You Gerhard use?
My Ducati friend have many sizes, so thats not problem, but wondering, that in Stage 1. kit is those jets.... Dont they know, what they put to kit?(with labelled note about open mufflers & K&N) Anyway totally different needles, than there was "as original". Anyway that main jet should function 100% only, when throttle is totally open and needle up... And i think, that 900 engine needs(uses) more fuel, than 750...

[paso750]

I really don`t know anymore. Don`t even know in which box I put the carb
You know that the numbers on Dynojet parts have their own system and are not comparable to others ?
So far I remember I did not change the main jet so I guess it`s the 140 I`ve been using.

The original jetting of the 750SS is:

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

The original jetting of the 900SS is:

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


G.

[Gwenadu]

from and old post: "I have 600 monster Mikuni carbs, KN cylindrics filters, very free home made cans, 150 jets and the needle at the upper level+1.6mm washers under the circlips. It runs well until 7000rpm but I think it is still a little lean over this speed... not often used!!!"... Now I have "Fedek" exhausts (idem DaveM ones)- less noisy and better balance at high RPM.

[eliatt]

Hi,
I use 140 main jets, and testing 145 on 750 sport with modified K&n filter element & after market cans.
I have installed the carbs ( taken from Monster 750 ) with the original 132.5 main jets, and when tested, were way to small .

[Finnpaso]

So, it can be, that need close 140 jets....

[Fraser]

Terve Antti,

My Mikunis are off a 1994 900SS, they came with a main jet size of 124.
The Dynojet Stage 2 kit came with 2 sets of main jets, a YJ144 (used if you have standard exhaust) and YJ148 to use if you have aftermarket exhaust. I've used the YJ148 and the bike runs really well, like trains toilet.
The kit also has slide springs, needles, washers etc. I have used foam pod type filters.

Fraser.

[Finnpaso]

Thanks, Guys, ill try those 142.5, what came with carbs Still waiting filters, should come close days. Already original throttle handly and choke are connected, also carbs are installed. Next fuel lines and tank for "breather pipes"(ill use one plastic can to all pipes and if problems, then put 2 cans). Btw, that original Weber throttle handly seems to work fine, so no need 2 cable system(that return spring is quite hard)...

[Finnpaso]

....and the bike runs really well, like trains toilet.

GOOD!, Fraser!!!

[Gwenadu]

..

so no need 2 cable system(that return spring is quite hard)...

Be carefull Antti, the carb can get frozen... and it is desagreable (and dangerous§) when the engine doesn't come back to idle! That happenned to me by cold and wet weather. I have thread the second hole of the throttle and now I have two cables.
Alain

[Finnpaso]

Thanks Alain for tip In that original Paso handly is thread ready for 2. cable, so easy to fit such, if needeed. Anyway i am driving with this bike only summertime and not in high altitude, so i think, i dont need it. In whatkind condition Your carbs get icey? Anyway, thanks!

[Gwenadu]

In whatkind condition Your carbs get icey? Anyway, thanks!

5°C...and Brittanny drizzle!
Something else: I have rode 1900km (in a week-end ) with a friend who has a Paso Weber-carbed. Cruise speed: 90 - 110km/h: Mikuni: 5.67 l/100km; Weber:5.2 l/100km. -It was for Moto-Légende at Dijon (F), a meeting of old bikes. Many thousands bikes, and only 2 Pasos!