blackmamba
Expert Class
Posts: 146
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posted March 04, 2010 02:11 PM
ZX11 carb guys step inside
I rode my friends zx11 today and had a few questions about the way it runs.
The bike was warmed up but being 45 degrees out it was not fully warmed even though i rode it for 15-20 minutes.
The bike starts right up and idles perfect.
The problem I am experiencing is at 5k rpms. The bike seems to hesitate for a split second and then take off smoothly all the way to redline. Is this when the carbs switch over to main jets?
What would cause an issue like this? How tough is it to synch these carbs?
After owning a vmax I am pretty decent at carb work. But I know better than to dig right in without asking questions first.
The bike does have an aftermarkey pipe and the previous owner said that it has been jetted for this mod. The PO was honest when he sold it to my friend as well and did admit that it seems to have been bogging around that rpm lately.
Thoughts?
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zxbob
Pro
Posts: 1692
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posted March 04, 2010 02:27 PM
To start - you need to verify whats in the carbs (jet kit)
Then get a plug reading to see how its running. If its been jetted, you may only
need to "shim the needles" to clear up the flat spot.
Bob
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Good parts aint cheap and cheap parts aint good !
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blackmamba
Expert Class
Posts: 146
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posted March 04, 2010 02:54 PM
shimmer me timbers! I had to do that on my vmax. how bad are these carbs to work on? you gotta pull the tank?
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Stevo13
Novice Class
Internet Police
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posted March 04, 2010 04:00 PM
quote:
..............you gotta pull the tank?
Before any work even begins...........yes. 
I will get back to you later tonight on this subject.
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'09 ZX-6R
'94 ZX-11
'07 ZX-14
'09 Ninja 250 (Jr's)
'08 Vino125 (her's)
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zxbob
Pro
Posts: 1692
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posted March 04, 2010 05:28 PM
Hmm . . . . are you "pinched" on time Steven ?
Bob
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juanvaldex
Parking Attendant
Coffee junky.
Posts: 17
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posted March 04, 2010 06:54 PM
you wil have to do some trial and error on those carbs. i can get them set maybe the third time off the bike. the needles are easy. yes, you will have to remove tank and airbox. not real tough. once you do it a few times. shim the needles and second clip from the top Also 2 and 3/4 turns on the air screws. is prettty close to smooth.
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Stevo13
Novice Class
Internet Police
Posts: 38
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posted March 04, 2010 09:58 PM
quote:
Hmm . . . . are you "pinched" on time Steven ?
Bob
Even though I am my own boss..............yes
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'09 ZX-6R
'94 ZX-11
'07 ZX-14
'09 Ninja 250 (Jr's)
'08 Vino125 (her's)
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Stevo13
Novice Class
Internet Police
Posts: 38
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posted March 04, 2010 10:15 PM
OK now that I have answered to the authorities here, let’s get on to the ZX11 carbs.
The OEM setting does have a flat spot at around 3500 RPM, not 5K. The "Factory" jet kit seems to be the best to remedy the problem. Stage 2 involves replacement of the needles, primary jets, adjustment of the idle mixture, vacuum synchronization and most of all, drilling a vertical hole on each of sliders is a specific location. This last step helps drastically with minimizing of the before mentioned flat spot. I am saying minimizing and not a complete elimination. Slight flat spot still remains under certain conditions, mostly evident in the first gear and to some degree in the second. There is none evident in the gears 3 to 6.
The Keihin carburetors are relatively easy to work on, as long as you put back all the parts in the right places. And fortunately, there aren't that many adjustments to deal with. Good luck with your project. 
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'09 ZX-6R
'94 ZX-11
'07 ZX-14
'09 Ninja 250 (Jr's)
'08 Vino125 (her's)
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BobC
Pro
Posts: 1736
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posted March 05, 2010 12:58 AM
 Edited By: BobC on 5 Mar 2010 09:33
This is going back a few years now but I fitted the Dynojet kit to my ZX-11 (ZZR1100 in the UK). They supplied needles and main jets. It was the different taper on the needles which cured the flat spot if I remember correctly. The bike still had the standard exhaust and the jets did nothing for performance, they simply used a lot more fuel, so I went back to the original size and just used the needles.
Our UK models were also restricted and we used to fit the carb tops from the 750 which allowed the slides to raise right up.
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Candy Thunder Blue 2006 ZZR1400
Stock wheelbase
Max: 205.4 mph in 1.25 miles
2012 ZZR1400 in Golden Blazed Green
Brock CT Full System. etc
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zxbob
Pro
Posts: 1692
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posted March 05, 2010 04:20 AM
quote:
OK now that I have answered to the authorities here, let’s get on to the ZX11 carbs.
Bob
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Good parts aint cheap and cheap parts aint good !
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blackmamba
Expert Class
Posts: 146
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posted March 05, 2010 05:41 AM
Thanks for the info. I'm glad my zx14 has FI! I knew that the vmax would be the last bike I would ever buy with carbs. Those carbs were fucking brutal!
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blackmamba
Expert Class
Posts: 146
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posted March 05, 2010 05:49 AM
Here is the answer I just received from the PO
"I think the jets are 155's It should be at a stage II jet set, which should be 4 into1 pipe, k&n air filter, and the 155's. I didn't go to the stage III because that would eliminate the air box and I didn't want to put sock air filters on the bike and bump the jets to the 160's. The needles where replaced end of 08 and synced. The last sync was done middle of 09 by Chicago sport and cycle on 147th and Pulaski. They told me I had the right set-up for the jets that were in the carbs. I though that I had blown the head gasket, but I didn't it was the water pump that went out, start of 09. Took the head off, cleaned it had new valve stem seals put in and the valves adjusted, and I cleaned the piston tops and cylinders. I put it back together and then had it re-synced in 09. I don't know if the needles have been shimmed. I haven't done it, but I don't know if the shop did when they did the carbs. If you want to play with the jets let me know, because I found the jet kit from when I replaced the needles. I still has the 150, 155, and 160 main jets. Hope this info helps"
Thoughts?
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SteddyTeddy
Pro
Posts: 1664
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posted March 05, 2010 06:16 AM
Did you try just giving the carbs a good cleaning first? Next I would get it on a dyno and have it sniffed to see where the AF ratio is sitting.
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blackmamba
Expert Class
Posts: 146
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posted March 05, 2010 06:23 AM
I put some seafoam in but only rode the bike a few miles so far. Seemed to have gotten better as the bike got warmer. It was only in the mid 40's here yesterday and I did not get the bike FULLY warmed up.
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Hellmutt
Needs a job
Posts: 2013
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posted March 05, 2010 06:33 AM
Edited By: Hellmutt on 5 Mar 2010 16:03
quote:
Did you try just giving the carbs a good cleaning first? Next I would get it on a dyno and have it sniffed to see where the AF ratio is sitting.
Exactly......first things first right? Then I would ask the guy if he'd send the remainder of the jet kit and maybe throw him a bit of cash for being cool like that.......wouldn't hurt to have some jetting options, especailly with a carb'd bike and the way they can fluxuate in varying conditions.
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FlatoutBu
Pro
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posted March 05, 2010 12:02 PM
Has the bike been sitting for awhile? The reason I ask was after dragging my zx11 out after winter it would take a few tanks of gas to get it running good again. After cleaning all the old stale gas out of it and running it thru a few heat cycles it was good. It also had the DJ stage 2 kit in it with the 155's.
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06 Blue 14
9.008 at 153mph @ 195 suited
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