fueling issue?

[airborneXS]

For starters, I have done some research on here, and im sure its a fueling issue, but I just dont know. I took the carbs off, and rejetted and cleaned them. I built a new exhaust, and the jets in before were just too big, the bike ran too rich and bogged down at higher speeds. it ran funny, so i started to sync. it does start in half choke, and in a few seconds i can close the choke fully, so it warms up nicely. well, after carb sync'ing, it seems that cylinders 3 and 4 dont fire completely. i can here spitting and coughing at idle from that side, and the pipes dont get as hot as 1 and 2. also, when i rev it, it takes twice as long to idle down. i have yet to carbtune so thats next. i gotta wait till tomorrow though as my neighbors are asleep.

[ManagerMike]

I'm thinking that during your sync, you inadvertently wound up with the idle stop floating and the whole set of butterflies stopping on the #3 throttle valve.
That leaves #3 closed off and #4 barely open with 1&2 running the engine mostly alone.
Go over the steps you took to perform the sync in your head and see if you may have missed something, as that seems to be the point at which things went south for you, a main jet change shouldn't have such a drastic affect on the idle circuit.
I'm sure some other minds will chime soon as well.

[airborneXS]

before i did the sync, i was running it to get the pipes warm to break in the wrap and header paint...thats when i noticed it. i thought the sync may have fixed it but it hasnt.

[petejw]

if ur using vac gauges
did u calibrate them?

[DGXSER]

You also want to check your mixture. I believe you said you had not tuned the mixture yet. No matter what the throttle plate position if your mixture is off it will not run well.

Synching is important, but you need to get the mixtures correct, then resynch.

And yes, if your using gages, hook each one to the same cylinder to see what they read first, that lets you "calibrate" them.

[airborneXS]

ok i will calibrate them when i get home. yes i still need to tune the mixture. im sitting i class at the moment sneaking a look at the site, naughty me, so i dont have a lot of time to look around at the moment. im sure theres already a wealth of information on here. ive never colortuned, what is the process? i just got a brand new one in from overseas.

[kevxs]

basically you hook up the colortune where your spark plug goes, fire up the bike, let it idle and adjust the mixture screw to get a nice rich blue color. if your too orange its too rich, too white means its too lean. you have to do this for each cylinder. turning the screw in will lean the mix, turning it out will richen it.

i had a helluva time the first time i did it. no matter what i did, it was always too lean, a good carb cleaning fixed it up.

p.s. dont turn the screws too far in or the tips will break off!!!! lightly seated is the max tightness for those

[airborneXS]

awesome...i will be doing that this afternoon...wilco...will advise...

[airborneXS]

thge first 2 cylinders, 1 and 2, seem to be getting plenty of fuel...i backed them all the way out and never saw it go yellow or orange tho, then turned it in i believe the first 2 are in between white and blue...the last 2, cylinders 3 and 4, i dont think are getting the right amount of fuel...i started with every idle screw about the same, where as 1 and 2 where burning bright , 3 and 4 almost had no color...turned the screw almost all the way out, then i finally saw some life to it...dark blue...i was able to tune 3 to a white i think, but 4, i couldnt get higher than a dark blue....any ideas? oh btw it pops and spits still from the exhasut coming from 3 and 4...1 and 2 exhaust sounds great...

btw, i downsized the jets 142.5 and 42.5 w/ 180 air jets....

[airborneXS]

i also tried to adjust the vacuum gauges ( calibrate them ) and found they all read slightly different on the same cylinder...so im pretty sure the sync is not accurate...how do i adjust the gauges?

[airborneXS]

i cant figure out how to calibrate these bastards...popped off the clear plastic front, theres 2 tiny screws that hold the face plate on, then on the back of the gauge theres 2 screws that hold the mechanism to the gauge body....

[DGXSER]

as for calibrating the gages, there is no adjustment, you just have to mark where the needle is on each gage at the same vacuum level or on that one cylinder. Use the first gage as the "zero" or basis of readings. If it reads 20" of vacuum, then you have 20" of vacuum on that cylinder.

Now, as you put each of the other gages on, use a marker or tape or something to note where 20" of vacuum is on the dial by where its needle is pointing. That will give you a consistent reading point on all four.

From now on that mark = 20" vacuum on that gage, ignore whatever the gage numbers tell you, do the math up or down from that mark for the actual reading. Of course 20" is a randaom number I am using.

As for the mixture, check your mixture screws, and the o-rings in there. Also check the length of the spring in there.

[airborneXS]

there are no orings, they are the earlier carbs....