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Discussion Starter #1
Hello,

My 98 zx6r has had this odd issue for quiet awhile (as long as I can remember):

When riding anywhere I can feel the bike bog down at anything above ~1/2 - 3/4 throttle. There is a very clear cut off point at which, immediately below I have good strong pull, but just passed and its an extremely weak pull all the way through WOT. In fact, its faster to accelerate below the "bog point" then at WOT.
--> Still accelerates above this point, but super slow.
This is particularly noticable on highway due to the acceleration involved with using more then 3/4 throttle in first gear. :thumbup:

Anyways, I've seen the "carb tuning / jetting chart" -->

( http://www.jba.bc.ca/JBCycle/Resources/jet-chart.jpg)

Which only lists the Main Jets and needle taper as being relevent up to WOT, But I am looking for any input that may shed some light before I take my carbs apart for the first time. (Already bookmarked the sticky)

Anyone have thoughts on any other possible causes?
 

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You could try running some StarTron though a tank of fuel. It should clean everything out.
 

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Discussion Starter #3
Thanks for the tip,

I've been adding SeaFoam to the tank pretty regularly (Last tank I added 1/2 a can to the last few litres (probably a 1:10 ratio of SF to gas)

Seafoam was chosed for the same reasons Star tron would be used, but it doesnt seem to help.

For discussion's sake, what could an alternative cause be in place of gummed up Main jets?

Any candidates?
 

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Is the bike all stock, exhaust changed?

It sounds like it is leaning out on the main jet, you might consider a jet kit. My ZZR600 was doing something similar at higher RPM and a Dynojet kit cured it.
 

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i would take the carbs off and check them out before you start messing around to much with dumping stuff in the tank. Seafoam and that stuff might help a bit but if the carbs are gunked up enough to cause issues like this, seafoam ain't gonna cut it.

You also may have carb diaphragm issues or something else that needs attending to in there.

If you don't feel comfortable tackling a carb teardown find someone who's got experience to help.
 

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Discussion Starter #8
The actual power house and exhaust is all stock. Small mods include HID and heated grips etc. nothing engine related.

No changes to any emissions items.

Will crack open the carbs in the coming weeks and post my findings for future readers.


Still love extra possibilities, as I know how much of a pain it will be to track down if it's still an issue once the carb has been gutted and cleaned out.
 

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Discussion Starter #9
As an added note, The bike is a 98 with less then 10,000Km on it, sat parked for years before I bought it from the guy who scared himself on it new. Haha
 

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Discussion Starter #11
Hey,

Sorry, must have been unclear,

It sat unused for a long time, but was all cleaned up by a mechanic. He did the carbs etc. at that time, but it was a couple years ago at this point.

Thanks again for the replies!
 

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Hi, new to the forum and saw this topic. I had an issue a few months ago, my 2007 ZZR 600 would buck at about 50 mph no matter what gear I was in. Would not go past 55 mph. Shop has it for a while and finally found a crack in the vacuum hose. Hose replace everything is good. Well.... Recently I've been having some odd throttle response as well. I would get up and go but unpredictable past 75 mph or so. Throttle is fully opened but bike hesitates, sometimes it goes most the times not. Has a hard time getting past 85 mph.

Shop says Dynojet kit should take care of the problem.

Opinions, comments, questions are welcomed.

Thanks

P.S. I do not do any mechanical work myself other than oil change and chain adjustment. Don't know how and don't have the patience.
 

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P.S. I do not do any mechanical work myself other than oil change and chain adjustment. Don't know how and don't have the patience.
Its great to know and admit your limits!

As for the jet kit its not the problem. My 07 ZZR goes past 100 with ease. Its stock other than the yoshimura can and needle shims. You need to have someone make sure all of the lines are connected correctly. I installed the wrong bolts it two spots of the air cleaner to carb adapter. The bolts where to long and and pushed the balance tubes between the carbs off. This causes fueling issues at speed due to the ram air intake. I would have someone make sure all of the hoses are installed correctly before any thing else.
 

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After the new vacuum hose a couple of months ago, 100 mph was not a problem. This just started about a week ago. Yesterday the bike actually cut off while I was ride around surface streets going less than 40 mph. It was a bitch to re-start. I actually thought it was the fuel pump. When I finally got it started again, played around with the choke. At full choke, the bike would cut off again.

Strange. Any ideas?
 

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Discussion Starter #15
Hey Anncam,

OP here,

Not familiar with the zzr600, but I seem to recall is being identical to my 98 zx6r.

Has anyone mentioned pulling and cleaning the carbs? Seems to be pretty common solution to our types of issues, haha.

As an update to anyone who cares, I've been ignoring the inability to accelerate at WOT, as I've been busy this summer. Have a mechanic friend in town this weekend to help with the carb clean process, will post results early next week if cleaning solved my issue.
 

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I'm having the jet kit done this weekend. Hopefully it will take care of the erratic throttle response. Will report back.
 

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Hello guys,
Im new in the forum and I got a 99 zx6G and I took it to the track yesterday and the bike was sputter between 7,000 and 10,000 RPM full throttle, I was wondering if some of you are being having the same problem and can help me out????
 

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Jet kit went in this morning. Bike feels great. Runs like new. 120 mph easy. No issues at WOT. My shop charge $350 installed.
 

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Discussion Starter #19
Jealous.


Here's my update:

Cleaned the carbs. All looked squeaky clean before I got in there, but cleaned regardless. (Guess there is something to be said for seafoam. Lol)
All jets were showing light.

Had a friend help adjust the mixture by:
Turning up idle to 2000rpm. Then turning in the mixture
Screws (all four at the same time. ) until the Rpms dropped off.
Turned all out until Rpms climbed. Rpms rose
Past 32000 before trailing off the other way. Turned back in till 3000rpms. Reduced idle down to 1300rpms.
Called that a day.

Let me know if we screwed that up in any way. Lol


Issue still persisting. Took out the plugs, #1 and #4 have rusted slightly. Looking for input there... Pics when I get to work.



Checked the spark on all four. All look good, #1 a little weaker.
How do I check the coils? I have access to a multi meter but need
Some Instructions. Haha


Thanks all!
 

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Discussion Starter #20
Also. Mixture caps were removed. Making me thing the previous owner was "screwing" with them. Lol

Anyone know how many turns out the mixture screws are at factory?
 
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