Figure this

[Artic_rider]

Anyone have any idea's for me here, I would love ya. Had the bike on the road finally the other day, and ended up getting stranded on the road due to a lack of fuel situation. What had happened, was the float bowl stuck open (not too sure because everything in the carb was new) Finally got her home after a humiliating wait on the side of the hiway, drained the oil and changed it, and pulled the carbs apart. Everything checked out fine inside, I guess the new needles just haven't really seated properly. I find myself doing the poor mans trick every so often, and rapping on the carbs with a screwdriver. Anyways, when I did have them apart, I noticed that the main jets were 110's across the board. The gears got turning in my mind, and I remembered that they are supposed to be 120's on the 2&3 carbs, so I tossed them in.

1) ? Is why are the jets different in those carbs...are they supposed to run hotter or something

Ended up tossing in new pilot jets as well, for giggles. Stock is 42.5 I believe, but there was 45 in it, so I went with some new 45's They weren't from the K&L kits, they were from the yadayada dealer. Put it all back together, having to do the poop mans float trick again...but fired it up. It caughed, backfired in the carbs and the pipes...and smoked a little blackish colour. I did preset the carbs, and they were damn close earlier, but I ended up pulling then redoing that via the Ken T way, and also changed out the pilot for the orriginals. Put it all back on, fired it up, and still getting the idle speed backfire. Can't even get it to idle half ass to set the pilot screws, so ya...Oh wise people...Am I missing something here. The 120's in 2&3 carbs, would that have something to do with this...I am thinking not, but I wanted to ask. Short of those, everything else is back to the way it was on the weekend when I went on my ride.

[MartyA]

The middle jets are up one size to help keep the middle cylinders cool. That's about all they are for.

Look for either a short or more gas leaking. Those sperk plugs fire twice for every 4 cycles.

[DiverRay]

Artic,
You may want to pull the carbs, then the float bowls. One at a time, check the FLOATS, see if they are twisted a little from someone trying to adjust them. They may be hitting the float bowl, and hanging up instead of shutting off the fuel.
I would also recheck the level on ALL the floats, each one (two per carb), to be sure they are set correctly. You could also set them 1 mm taller than the book calls for, to lean it out slightly at low RPM's.
Ray

[Mike Woodman]

Might want to check the air box if you haven't allready. The field mice built a cozy nest in my air box and the symtoms were similar.

[motoman]

Don't know what elev. your at there, but the 42.5pilots should work fine. Are you using stock airbox? To give you something relative to go from, I' m at 4,800ft. elev. 81 tourer is running 105mains, 42.5pilots, float level is 24mm(15/16"for me, triple-checked this time) which was another story, maybe too much Irish Creme in my coffee first setting, idle mix screws out 3.5 turns and have yet to check carb sync. or re-adjust idle mix and smoot idle, pulls smoothly any gear from below 1,500rpm up to redline, 35mpg around town, 39.8mpg@70-75mph on highway. No popping at idle or de-celleration. Could dial it in to maybe do the occasionall 43-46mpg that it would get when new, but happy, and if it's not broke , don't fix it, leavin' it alone for now. Hope the jetting numbers give you some idea where to go from there. Otherwise, from your symptoms, may have some hidden culprit going on with carbs.

[Artic_rider]

Air box has been taken off...and I am running two pod filters...going to jet down the mains again I guess, and see if I can at least get it to idle.

[motoman]

Jetting down mains won't help with the idle. pull carb assembly off and remove float bowls and set proper float level setting first thing. your idle mix screws are on top front of carbs. They may need adjustment. Follow tech info CAREFULLY for all this.

[Artic_rider]

ya...but I still have to at least get it to idle a bit to set the idle...but I am going to reset the floats tonight

[strom]

I thaught 78E had same size jets across all 4.
Later models had larger jets in 2 and 3.

LP

[CUBuffs]

I've got an 80 SG that also has 110's across all four. Should I be changing 2&3 to 120's, plus I also have 4 into 1 exhaust?

[TopCatGr58]

Hey CUBUFFS,

Don't bother. My 81 also had 110's, after I rebuilt with big bore, put 117.5's across all four, runs fine!!!
T.C.

[CUBuffs]

Thanks T.C.

[Artic_rider]

Thanks guys for the insight on everything. Got her to idle really well, I am having some low rpm stumble issues, but I am in the process of getting those kinks out. Once it's past 3000 rpm though...holy mother mary of god. I actually pulled the front tire off the ground about an hour ago on a small test ride. Still can't wipe the grin off my face guys.

[LoHo]

Rider, after my carb rebuild, I had a gas leak from #3, but only when running. That told me that my petcocks were holding, and the needle was not. After reading every carb thread here, I took those little keeper wires off of the needles, and have had no problems since. Three was flooding so badly that gas came out the exhaust when the bike was cold. I guess that it vaporized in the pipe when warm...yikes!

[Artic_rider]

You know, I was kinda wondering about that, because on a spare set that I tore apart, there wasn't those little clips on them. I seem to have solved that problem, but I do have to change out some jets once they get here, so I will also give that a whirl as well. Thanks for the tip mate