mikuni running rich..

[birdduck]

okay so my rear bank is way rich(black plug) and the only thing i can figure out is it has to do with the choke circuit...

this little pipe was broken on the test fitting by a rogue finger placement...
i was able to solder it back on but not sure what its for?? i have looked for quite some time trying to figure it out..
input????

this is on the rear bank carb, i am assuming this is tied into why its running so rich..

(update)
so i went out and played around with it, i looks like it only uses that circuit when the choke is opned, no other time..
could my float be sticking? i have not pulled the back apart after my last cleaning and its been running very rich since the carbs were put on. maybe a clogged air jet? making it draw in to much fuel at idle? i will tear into the carbs tomorrow after work

[Derek]

Check the needles that block off the choke circuit when it is closed. They are made of plastic and the tips wear.

[birdduck]

if this helps, it stumbles very badly if i just crack the throttle.. it can actually flood the rear bank if i let it stumble for to long..


just had an epiphany.. when i had the carbs off to re seal the fuel inlet i didn't re balance the carbs.. i know what i am doing after work....

[paso750]

check the pages O.48 and O.67 of the file "Elefant750..." file https://app.box.com/s/gslivfnzo4d3ak79cqs1
Balancing the carbs is a good idea (of course all carb adjustments should be done with air filters installed) The spark should be good now that so can`t be it.
In case you strip the carb verify that the washer and O-ring of the pilot screw are there and in good condition. If you remove the choke plungers as Derek suggested note that there are clips on the other side of them that have to be compressed if you want to pull them out. Also remember which way around they were installed as the front section has a round and a flat side. (see also Haynes manual 3.4) Small rubber bits of squashed O-rings can block carb channels.

Does the choke mechanism fully move back to the left and is there no tension on the cable when the choke lever is closed ? On the picture it looks a bit as if the choke mechanism is touching the rubber boot but that would be impossible.

What`s the exact jetting of the carb ? If it`s from Phil could it be it has a Dynojet kit for a 900 installed ?

G.

[birdduck]

the choke isn't hooked up, i have never needed it. i will check my mix screws and such.. but this only happened after the last time i took the carbs off.. before it was great.. i will confirm that the choke lever/bar is free moving i have a few times already, could be just the angle of the pic.
going to stay after at work and play around with it.

[birdduck]

okay carbs balanced, choke lever is free of obstructions. still sputtering.. i have a 140 main and needle
is on the 3rd clip.. slip on pipes and a pod uni's at 5500 feet.. air mix screws at 5 turns out(half turns)

[higgy]

turn it 2 more half turns out,does it get better or worse ? How about 2 half turns in ?

most jap carbs are happy at 3 half turns from seated

[birdduck]

should i drop back down to the 130 main? if i need to i can fin tune with the needle position.
from some research it looks like the 140 is run by the 906 with pipes, thus being far to much fuel for the 750, and would explain why it kills all the butterfly's when i ride by... i will run dig into it tonight.

[paso750]

no don`t.
Look at the FAQs. Most jets are the same in the 750SS and 900SS setup incl the 140 mains. The difference is the needle jet, the position of the clip and the pilot jet. The main jet has no influence on idle that`s the pilot screw and jet (you can read all that in the Elefant750 file btw).

If getting a used carb I always recommend to verify what jetting it has and to write down the values of every single jet, needle etc. That`s the best prevention for later headaches. Also check if the jets are original. Mikuni jets have this symbol stamped on them.

Dynojet jets have YJ and a number stamped on them instead. A Mikuni 140 main jet is not the same as a Dynojet YJ140. There are conversion tables you`ll find in the internet.
A random approach will only work with lots of luck. You need to know your baseline.

The pilot screw with a DJ kit is 3-4 turns out btw.
http://www.dynojet.com/jetkits/motorcycle/ducati.aspx

But while your jetting might not be totally right it wouldn`t explain why the engine is running rich only on one cylinder and why the carb worked fine before and now it doesn`t. What exactly did you do after you pulled the working carb off ? Go through all steps.

If the carb manifolds have threads for hose nipples are they sealed with a copper washer and small screw ? Was the fuel line accidently connected to the fuel chamber overflow, is the breather for the diaphragm clear? Does it do the same with the airfilters on ? I doubt it`s any of this but it`s worth checking.

[birdduck]

found the float needle on the one side, the little spring thing was stuck out..
still dropped back down to the 130 witch i think is a stock jet.. dead spot is almost 100% gone, will check the plugs on the way home and see how they look.
don't forget i am at 5500 feet elev.

the kit came with 3 sets of jets: 140-144-150
http://www.dynojet.com/pdf/7201.pdf this be the one

[birdduck]

whent for 120ish mile ride today, bike did great.. setup is as follows: 130main needle on 4th clip and 5 turn(2.5) out.. still rich at idle but i am going to play with the mix screws to see if i can get a sweet spot

[paso750]

check the size of your pilot jet ! It`s 37,5 for a 750 and 42,5 for a 900SS.

[birdduck]

i will tomorrow, also going to confirm float hight

[birdduck]

okay got the low down. 70 needle jet 140 main 40 pilot.. i picked up some smaller pilots but they were the wrong kind

[birdduck]

So I think I may have it pegged. ... 37.5 pilots but I have to run the mix screws at 4.5 out? I was getting a lean spot it seemed at 1/4 throttle.. so I moved the needle clip down one clip to 3 and it helped, but added more off throttle sputtering