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Discussion Starter · #1 ·
I have a Gpz 1100 all stock and it sat for years and only has 4500 miles on it. Tore down carbs and replaced float needles and went threw all carbs and cleaned. So bike idles and there is no mid range it falls on its face and if you roll throttle easy it’s ok. I’ll put new plugs in and run around the block and they are black. Running rich. ????? Needle is stock and can’t move clip. Jet is stock smallest they have. Compression is same across the board. All plugs are black across the board. Any ideas I’m pulling my hair out with this bike. Please help
 

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Did you check the float level setting? Verify the floats are not sinking? Check float valve operation by blowing into the fuel inlets and lifting the float to the close position?
Did you check that the fuel jets are seated in the tubes? No blockages to the air jets?
Did you check for critter nests in the air cleaners?
 

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Discussion Starter · #3 ·
I have adjusted floats to 18.5 mm book specs. Float needles seated no leaks. And replaced with oem float needles. Checked all floats for leaks and are good. Checked all passages and went threw all jet holes cleaned. Replaced new air filter and cleaned box.
 

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Discussion Starter · #5 ·
Put timing light to ignition wires and ride and light fires at all times. So ignition is not cutting out.
 

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Discussion Starter · #6 ·
Adjusted air/fuel needle in to lean out and can not get to lean out. Its a fuel screw on this not air screw. Bike idles fine. Blip the throttle it’s good. Go to crack open to 1/4 to half throttle and falls on its face. If I go threw slow it will tach up and no issues. I was thinking of going to a stage one kit so I can adjust clips on needle? Can I adjust floats to lean out the carbs?? If spec is 18.5 do I adjust to like a 17.5 mm. Or is this just for idle purposes?? I’m not a bike tech but do understand the mechanics
 

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Hi, I'm late to the party, sorry about that.

I would think the fuel levels would have more effect on slow speed running instead of making it balk at the throttle.
If it has the stock air box and exhaust system... a jet kit will only help to confuse things even more.

Does it have the stock air box and exhaust?
The answer to that question depends on where we go from here....
 

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Where we go from here is this suggestion as the problem you have is VERY common and has happened to lots of us:surprise:

This trick has saved my Bacon many times with my bikes doing the same thing as yours:

Buy a bottle of Chevron Techron (the best) or Seafoam or Lucas Carb/ Fuel injection cleaner and put at least 1/2 of the can in your fuel tank and find a place where you can ride the 'snot' out of the bike, reving it out as hard as possible, downshifting at high rpm's, just short of 'lockup,' and continue this for as long as it takes for the symptoms to disappear:smile_big: This uses all circuits in the Carb's from idle to main's.:wink2:

This 'cure,' can sometimes do miracles and keep you from having to disassemble the carbs again. This is all 'fuel related,' with the mid-range jets still clogged up. As long as your floats haven't developed a leak (Shake them) and need to be replaced, don't touch your float level. I have never, ever had to adjust the factory float level on any bike.:wink2:

The last bike I had to do this to was in 1999, on my 1997 Suzuki Bandit 1200S, when I had let it sit in my garage since I had a brand new Honda Valkyrie Interstate that got my attention more than the Suzuki.:plain: It took about 100 miles of hard riding, on rural country roads for the Techron to completely clean the fuel system and make the bike run like new again:grin:

All of my bikes and my Cages periodically get the same treatment to hopefully keep the 'Demon Ethanol,' from doing it's dastardly thing from the fuel tank to the exhaust:surprise:

Sam:nerd:
 

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Where we go from here is this suggestion as the problem you have is VERY common and has happened to lots of us:surprise:

This trick has saved my Bacon many times with my bikes doing the same thing as yours:

Buy a bottle of Chevron Techron (the best) or Seafoam or Lucas Carb/ Fuel injection cleaner and put at least 1/2 of the can in your fuel tank and find a place where you can ride the 'snot' out of the bike, reving it out as hard as possible, downshifting at high rpm's, just short of 'lockup,' and continue this for as long as it takes for the symptoms to disappear:smile_big: This uses all circuits in the Carb's from idle to main's.:wink2:

This 'cure,' can sometimes do miracles and keep you from having to disassemble the carbs again. This is all 'fuel related,' with the mid-range jets still clogged up. As long as your floats haven't developed a leak (Shake them) and need to be replaced, don't touch your float level. I have never, ever had to adjust the factory float level on any bike.:wink2:

The last bike I had to do this to was in 1999, on my 1997 Suzuki Bandit 1200S, when I had let it sit in my garage since I had a brand new Honda Valkyrie Interstate that got my attention more than the Suzuki.:plain: It took about 100 miles of hard riding, on rural country roads for the Techron to completely clean the fuel system and make the bike run like new again:grin:

All of my bikes and my Cages periodically get the same treatment to hopefully keep the 'Demon Ethanol,' from doing it's dastardly thing from the fuel tank to the exhaust:surprise:

Sam:nerd:
That is provided it is dirt/Varnish not a setting issue or a chunk of rubber from something stuck in a passage since he had worked on them.

GPZ I hated carbs for years because I feared them, sometimes you must take them back apart a few time and methodically go back through them making sure everything is in its place where and how it is supposed to be. Open your manual or rebuild sheet start at the first step and go one step at a time making sure everything is to spec exactly, until you know what your doing you will get you best benefit from this, take no short cuts until you know what your doing.

Also make sure as Semi said that you have stock pipes (slip ons don't count in most cases as long as it is stock header pipe) and jets etc. Any of those are changed it will change what your outcome is in most cases, most I say, not all. I am pretty sure the GPZ 1100 is one of them.
 
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...... making sure everything is in its place where and how it is supposed to be. Open your manual or rebuild sheet start at the first step and go one step at a time making sure everything is to spec exactly, .......
This ............. ^
 

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Discussion Starter · #12 ·
Thanks every one for your posts. As of now the bike is 100 percent stock other then aid filter which is a foam filter. Not oem. I’ve set floats as to where bike idles and I can run threw gears with no issues. If I get on throttle about mid way hard it falls on its face. I have had these carbs off 25x or more and went threw each one very precise on float settings to each and every passage. I ride for a few minutes and bring back and check plugs. All are black. Sandblast each plug again and same thing. Changed plugs same issue. I can not get the plugs to clean up. I drew in air/fuel stew and no change on idle. So that tells me carb is rich. All stock jets mains exhaust . It only has 4500 miles on it. All 4 carbs the same. Bike will idle high at times and crack throttle n will at times take a sec to idle. Checked for any vacuum leaks and none. I have been threw this bike from top to bottom. I checked ignition with timing light why riding to see if cuts out in mid range and light stats on. Does not cut out. Really fed up. It’s 500 to a grand to have them done which I think I can do. Just cannot figure it out.
 

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With the main jet and main jet holder (with emulsion tube) removed have you sprayed carb chem thru all passages of the carb body itself to be sure all are clear?
There are air jets just inside the back (rear) of the carbs venturi. Most have two, one for mid range / main jet and one for slow speed / pilot jet running.
The smaller of the two is for mid range / high speed / main jet running. When you spray carb chem thru this air jet you should see a good flow of chem coming out where the main jet holder has been removed.
Have you done this? Is this area of the carb body itself clear?
Are you sure there are no missing "O" rings, washers / parts or whatever because it sounds like this area could be where your problem is.

Jet needle and needle jet: (My terminology).

What I call the 'jet needle' is the long needle that is attached to the bottom of the slide diaphragm and is not adjustable like it is with a jet kit.
The 'Jet needle' works with the 'needle jet'.
The needle jet protrudes up into the venturi a little and is held in place by the emulsion tube/main jet holder assembly.
All of that just so I can ask... The needle jets are not missing are they and are they installed correctly? (Meaning not upside down).

One other possibility. >Probably should have started with this.< Lol
Are you sure the jet needles are installed correctly so they stay put and can not move independently of the slide diaphragm.
If they are somehow "floating",so to speak, that could cause the problem you describe.
Wow, that was long...:surprise:
 

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Discussion Starter · #15 ·
Thank you for all your help. And I still trying to get this bike rite. So this is where I’m at now ... carbs were in bad shape and found when I cleaned . Let me say that only lower part of bowl was bad in the carbs. So what I found was when I cleaned carbs I ended up drilling pilot jet out this making it rich at idle. So I picked up new ones and installed. Went over every hole in each carb again. So I start bike and low and behold it will only fun on choke...wtf!!!!!!! Frustrated. All passages open n clean. Before when pilot jet was drilled it idled just ran rich. Now put new ones will not idle l. Has to be choked to run. And yes it’s the pilot issue. I have pulled back apart went threw again and same ****... I’m at my wits end. The bike is 100 percent stock. 4500 miles on it. I’ve ran it up down the street on old pilots ran strong idled just fouled plugs.... FRUSTRATED. Any help would be greatly appreciated.
 

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highrise317

hey buddy I feel your pain..ive got a 1996 gpz 1100 and am going through the same ****...no matter what I did or how many times I did it I could not get that beast to run right.ive had those carbs off that bike 5 times in the last week to think I almost got it right to just be let down and well pissed off AGAIN...so I live in Indianapolis and one of the local shops around here has nthing short of a bike god in it..the place is called cycle recycle II,and his name is rob.... I gave him my carbs and 5 days later he gave them back... they looked brand new,new EVERYTHING!!!! I mean they looked like they came right out of the box,but better yet they worked,and for the past 10 days not a single hiccup..and the best part was it was $300 total...that's his price parts and labor..he will contact you you and keep you uo to date during the process..very interesting guy and he will keep your attention...hes fun to listen to as he knows everything I think.my only problem is now the season for us indy boys is coming to an end quickly and I still wanna ride but patients is key when dealing with ths stuff and well,,,think ill just bundle up and push it till the wheels fall off...good luck with ur bike and stay safe out there
 

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Discussion Starter · #17 ·
Update. Now bike idles. But when I adjust idle it won’t go above 1200 rpm starts to die out. At idle if I ease on throttle dies out completely.
 

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With the pilot jet, main jet and main jet holder (with emulsion tube) removed have you sprayed carb chem thru all passages of the carb body itself to be sure all are clear?

I ask because many times people don't understand the passages (ports) inside the carb body are very hard to clean without soaking the carburetors and spraying carb chem thru the ports until a healthy flow of chem can be seen coming out of every port outlet. (All jets removed).

When you spray chem thru the pilot circuit (pilot jet removed) you should be able to see a good flow of chem coming out of the port where the fuel mixture screw outlets into the venturi.
This slow speed outlet port (for fuel mixture screw) is located in the top of the venturi and in front (engine side) of the throttle plate.

All of what you describe sounds like you still have plugged ports inside the carb body itself.

See my post number 13 about mid range / high speed port checking and cleaning.

Note:
I looked up a 1985 year model GPZ to determine where the fuel mixture screw is located. This one shows to be in the top of the venturi, most (or many) are in the bottom.
 

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Discussion Starter · #19 ·
It is a 1996 Gpz 1100. I had carbs sonic dipped. I have sprayed every port and all have good flow. I blow with air all have good flow. I can get bike to idle but it’s only to a certain point I try to raise idle it dies out at 1300 rpm. Before it was running super rich on stock pilot I tryed to clean with wire but I have real small hand drill bits and drilled to big causing rich condition. ( my mistake) now I bought stock ones. Now bike idles before and ran 95 percent but fouled plugs. (Drilled pilots). Now did not change anything and put new pilots in and bike will idle but dies off twisting throttle. I can choke a lil bit it will come up. ( yes lean condition I know) . Checked all passages hundred times . Great flow. I use to re do bikes years ago but haven’t done in a long time but it comes back. Air/fuel screws which I have a fuel screw is at 2 1/2 turns out on all 4 carbs. I plugged all vac ports also.
 
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