need some bandit carb help

[92GSX750]

Im in need of a little carb help. I have the bandit 1200 motor swap finished but today when i tried to start her I noticed a couple issues.

For those that are not familiar with my build, its an 02 Bandit 1200 motor, with 04 Bandit 1200 carbs, in a 92 Kat. The carbs were fully dis-assembled, soaked in berrymans for 24hours, re-assembled with all new gaskets and o-rings, and a stage 2 holeshot jet kit installed.

Now today when I tried to start her for the first time, it wasn't easy. I primed the carbs, applied choke, an nothing. It just spun, acted like it wanted to catch but didn't. Once I removed the choke and opened the throttle a little she fired, but sounded off. After 10-15 sec I had to shut it down. There was gas dumping out the front of the carbs thru the filters. Shortly after shutting it down I also noticed what appeared to be fuel dripping from the exhaust collector. I'm not 100% positive on that though because whatever of was was mixed with the fresh paint on the exhaust and fuel was everywhere.

I pulled the filters and noticed the fuel was dumping out of carbs #1 and #3 where I'm pointing in the below pic.



Its the hole on the bottom right and it is the same hole on both leaking carbs. Can anyone tell me what circuit that is. Trying to figure out where I messed up in rebuilding the carbs. I tore the carbs apart over a year ago for the rebuild and re-assembling them was just done recently. Obviously I forgot how something went together

Another thing I noticed was when the bike was running, any application of choke would kill the motor. The idle wouldn't rise at all, just instantly die. Any help would be great. Thanks

[scottynoface]

Floats installed incorrectly?

I managed to do that once, no clue how.

[92GSX750]

I'll have to check that. Thanks

[OleDirtyDoc]

sounds like the floats.maybe the needle has some crud in it and isn't closing fully when the float rises.my 700 vulcan(cv kiehan carb,)does that once in a while.usually when i don't put any stabul or any additive to counteract ethanol

[Kreylyn]

As mentioned, the primary point would be the carbs over flowing fuel. Faulty float needles, bad seats, missed/bad orings around the seats if they apply, sticky/incorrectly set float heights, etc...

To narrow down the issue...

Drain the fuel out of the carb bowls. Hold them upside down once you have. Blow on the fuel line hard. If you can move any air at all it's probably not an adjustment issue, but more likely an issue with bad parts (cracked/damaged/missing orings/needle tip), or something holding the needle open from seating like trash or a bad condition seat.

If you can not blow any air through at all ... it's most likely just a float adjustment issue.

Take the bowls off and attempt to fix.

If you can move air while they are upside down for your first test... with the bowls off, keep doing the test again after you attempt to fix it. This is to test that it has stopped.

Once you get the carbs to pass the air test upside down, put the bowls on... fill the carb bowls through the fuel line on the work bench, and again... blow on the fuel line. When the bowls are full, you shuold not be able to move air either. If you can, you still have an issue.

Krey

[92GSX750]

Hot dang, thanks for the detailed explanation Krey. I pulled the carbs, drained them, flipped them over, and no air would move thru.

I then put the carbs on the work bench, pulled the bowls, and blew air again. This time I lifted each float, one at a time and let it close on its own. One thing I noticed was that the float needle did not seal the air completely. Not sure why just yet, all 4 float needles and seats are new.

Also, I just remembered something from yesterday after reading your post krey. After the initial shutdown from fuel overflowing, I was searching for the cause. I noticed that there was fuel all around the main needle. When I lifted the needle, fuel dumped from the jet into intake. I'm bringing that up because the holeshot directions had me cut 28mm off the diaphram spring. I wondered about that then and now I'm wondering a lot more. As I think about it that spring keeps the pressure on the needle. By removing some of the spring there is less pressure there.

[Kreylyn]

Hot dang, thanks for the detailed explanation Krey. I pulled the carbs, drained them, flipped them over, and no air would move thru.

This generally would point toward the float height settings.

I then put the carbs on the work bench, pulled the bowls, and blew air again. This time I lifted each float, one at a time and let it close on its own. One thing I noticed was that the float needle did not seal the air completely. Not sure why just yet, all 4 float needles and seats are new.

So it passed the first test, but failed the second?

The difference is the flaots being actuated... so possibly also look at how freely they are moving and if there is any resistance that might be holding them open very sligthly.

Also, I just remembered something from yesterday after reading your post krey. After the initial shutdown from fuel overflowing, I was searching for the cause. I noticed that there was fuel all around the main needle. When I lifted the needle, fuel dumped from the jet into intake. I'm bringing that up because the holeshot directions had me cut 28mm off the diaphram spring. I wondered about that then and now I'm wondering a lot more. As I think about it that spring keeps the pressure on the needle. By removing some of the spring there is less pressure there.

The main jet needle would have nothing to do with fuel over flowing. How it's going to run once you get the overflow issue fixed on the other hand, I can't say. I'm not a very big supporter of kits that request/require you modify parts in your carbs... at all. It generally ends in epic fail.

Krey

[92GSX750]

Alright, I have been thru these things thoroughly. Float height was off and none were consistant with each other. I must have forgot to set them when I re-assembled everything. But they were not that far out of spec, maybe half a mm.

I inspected every little part of the float/needle assembly. Could not find any trash or reason for binding. The needle, needle seat, and o-ring are all new and looked fine.

I double checked the A/F setting and that all the jets were the right ones and in the right places. All good. I did have the needle clip in the wrong slot, so I fixed that. Other than that everything looked good. Which it should since everything inside the carbs is new except for the mid jets and the main needle jet holders.

I have the carbs re-assembled and sitting in the vise with a temp fuel tank feeding them.



They have been siitin there for about 20 minutes and there is no signs of fuel anywhere. Going to let it sit there a little longer and if still there is no signs of leakage, I'll re-install them on the bike and give her a go again.

Also, I did find out that that passage where the fuel was coming out in the first picture, is linked directly to the main jet circuit.

[spencer volk]

float height

I agree on the float height issue,,,also make sure you got a good fuel filter between tank and carbs.would be a shame to dirty up those clean carbs.i might also add that I have encountered egged-out main jet emulsion tubes,thereby allowing fuel leakage past the needle,making tuning difficult.what happens is over time the needle erodes away the motor side of the emulsion tube,from the vaccuum pulling on it.if you take your airbox or filters off and look at the needle while runningat idle,you can see the fuel comin out byneedle...if thats the case new emulsion tubes are in order.

[arsenic]

You realize the carbs on your GSX1100F and the 98+ carbs are completely different right? The "emulsion tube" is totally different. The 98+ have a needle jet, and a needle jet holder. It's far less likely that he has a egg shaped emulsion tube.

[OleDirtyDoc]

sounds like the floats are set correctly now,because if not,it would flow gas out of the carbs in lees than a few minutes.after 20 mins i think you are fine

[92GSX750]

Yeah these carbs are very different. I actually like these better.

Back on topic, the carbs held fuel just fine for almost an hour. So I went ahead an re-installed them. Fired the bike up and she ran a lot better. Need to pull the plugs and make sure they aren't fouled though. However, after shutting the bike down and inspecting everywhere, I noticed a very small amount of fuel on the front of the #2 carb now. Nothing like before though. I believe the float needles are sticking ever so slightly once in a while.

I'm hoping that this issue corrects its self over time as they wear in. If not I'll go back with the original needle and seat.