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Discussion Starter · #1 ·
hey guys, this is my first post on this forum. i'll tell you my zx6r tale and maybe some of you can help me out with fixing my issues.

about 3 months ago i traded a truck i had to one of my friends for my current bike, a 2002 ZX6R. the bike had been turned into a stunt bike, with the front and side fairings removed, gauges removed, steetfighter headlights added, D & D exhaust added, +10 rear sprocket installed, and a stunt cage installed.

at that time, the bike ran perfectly (or so it felt). revved up hard to redline in every gear, at any speed. keep in mind that this was with no front fairing installed, so the intake air was entering directly into the frame holes, with no ram air components installed. i'll add some pictures of the bike when i received it, and pictures of it now, so you can see how it was set up previously.

i hated the stunt bike setup and wished to return it to stock. luckily, my friend had most of the stock components in storage, so i was able to restore the bike partially by removing the stunt cage, and reinstalling the front and side fairings and gauges. there was a bunch of little parts that i was missing or had damaged too, and i am still working at putting the bike back to stock.

anyway, as soon as i had the front fairing installed (along with all the ram air components), there were issues. the bike revved up great at idle and in first gear, but as soon as i built up any sort of speed (anything over 40 or so it seemed like), the bike would sputter and cut out. if i pulled the clutch in at high speeds, it would stall.

well i put 2 and 2 together and figured that the airflow has changed, and i assumed the ram air was forcing too much air into the airbox at speed. so pulled out the 2 tubes that connect the ram air system to the airbox (the tubes that run through the frame rails), and the power improved dramatically. but, it still cuts out and sputters over roughly 9k rpms in 3rd or 4th gear, and over 7k in 5th and 6th. also, snapping the throttle open at higher speeds results in no response, almost like i let go of the throttle grip. if i open it smoother, it will run slightly better

the running condition is very dependent on the speed of the bike. at low speeds and in the first 2 gears, she sounds and pulls great. any faster than that and it breaking up. and again, this is with the full fairings, but minus the 2 tubes for the ram air.

i assume the carbs need to be rejetted. i have no idea if the previous owner(my friend only had the bike for 3 weeks, he bought it off of craigslist) rejetted after adding the D&D exhaust, or after removing the fairings.

my questions are: does this sound solely like a jetting issue? if so, how hard is it to rejet the carbs myself? i'm very mechanical, but i dont want to start a job if its going to involve specialized tools, etc.
also, whats the best brand for a jet kit, and wheres a good place to buy from? any recommendations for jet sizes to start out with? any tips, tricks, or secrets i should know about in rejetting this bike? know of any good write-ups online on how the jet the carbs in these things?

any information on the subject is MUCH appreciated. i got a rough estimate from a shop near me of $130 for the jet kit, and $160 for the install. i would have immediately had this done if i know it will cure my problem, but i hear jetting is more or less a lot of testing to see whats the best size jets to go with. i dont wanna pay that much and have it run 'just a little' better.

thanks for any and all valid replies!

here are some pictures of the bike--2 pics of it the day i received it, and 2 pics taken a couple days ago




 

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I am in the middle of an air fuel ratio conundrum as well and I have been doing a lot of digging and research.



The RamAir system has 2 major parts. The large tubes force more air into the intake side of things. The smaller tubes are connected to the carburetors to raise the pressure on one side of the fuel to force it into the engine. More air+more fuel = more power! Like you said, it sound like it is leaning out, I can think of a few reasons.

1. Small hoses blocked, not forcing gas in. Check the small hoses and their filter for any debris. With the air box off blow lightly into the small RamAir hose and you should see fuel dump into all 4 carbs.

2. Bike was tuned to run without the RamAir system. This is not uncommon for stunters to do when they take off all of the RamAir stuff.

Rejetting is rather ez, it is tuning that I find to be the hard part. To rejet just follow these instructions http://www.gstwins.com/zx6r/zx6r_shim.htm TAKE CARE of the o-rings. A lot of people act like it is a huge hang up, but just be careful. There is a lot of useful discussion over on sb.net as well http://www.sportbikes.net/forums/zzr-mods/ (00-02 ZX6R = 05-08 ZZR600)

Let me know if that helps at all, here is a little description of the issue I was having, if it helps anyone.

I have a 99 with a full D&D kit and a Stage 3 DynoJet jet kit. It would run fine, except after long periods of constant RPM, or with strong head winds. My mileage would suffer greatly (35mpg running ok, 30mpg with a few bogs, and as low as 19mpg). Because of that and the exhaust smell that was described to me I knew I was running rich. So on my past road trip, after experiencing strong headwinds and it making the ride MISERABLE, I decided to pull off and plug the smaller tubes to stop it from dumping fuel in. After that it ran just like you are describing, basically gutless. So for the trip I ended up taping up the whole front end and popping off the resonators to completely bypass all of the RamAir system and just vent the airbox to atmosphere. After I got home and took the bike apart I found that the shop had left off the 2 caps on the airbox, letting all the pressure escape, but the system would still dump in more gas.
 

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Discussion Starter · #3 ·
jakester thanks ALOT!

i used your info to look over my bike, and i realized i always had the smaller tube hooked up, not knowing what it was for. so while the ram air was disabled, the force of the wind speed was dumping extra fuel into the carbs when i was going fast. i simply disconnected the smaller tube, and the bike runs great again.

i do plan on hooking up all the factory ram air stuff again and having it rejetted, but now i can get through the season with no problems thanks again!!
 
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