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Discussion Starter · #1 ·
my bike doesnt accelerate very fast.. it takes a while to suddenly fly..

seems a carbuarting problem.. but im not sure if i should change the lower jets for bigger ones.. because the higher jets seem fine, the bike after 20 miles per hour goes better.

or needs more air or mor gas?

now it has 35, i live in the altitude..

waht u recomend?

Ps: is not a clutch problem...

(its for a Kawa gpz 400)
 

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Discussion Starter · #3 ·
Can you give us more information on what it does when you first start out. Is it missing, hesitation or what? http://www.kawasakimotorcycle.org/forum/mechanics-corner/55577-bike-problems-read-first-please.html
m , the bike is a really pain to carburate i have tried all jets and combinations i guess.

i have tried 110 jest /the ones that works better)

140 jets

115 jets

85 jets

95 jets and 3 turns of air, two and a half.. 3 and a half..

and nothign seem to work well.., of course some combinations work Worst that i can tell.. but i cant find the right combination!.


the bike starts pertty well , actually cold.. the first meters the bike goes fine.. but if i Suddenly open the throttle (accelerate) the bike stalls like the odometer pass the 3 k with fifficulty, after that the bike flies, until it goes to 8 k the bike again has problems..,
so im not sure if that is exess of air or gas.. ive tried all and im tired of taking out in the carbs everytime=P

any suggestion?.

its for a Kawa 400 gpz, i live in the altitudes.

Thanks.
 

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i would guess it is a carb problem. i have similar problems with my bike and it turned out my carbs had some unnecessary dirt in them. i would assume that your carbs are clean being how you did the jets so many times so if its not that then maybe an adjustment problem. i dont claim to be a professional mechanic but that would be my 2 cents. hope this helps?
 

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RideOrDieWarren
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Carb Tuning
You have three areas to tune: idle, midrange, and upper. You start at the main jet and work your way down to the mixture screws.

Approach the mid and upper by "feeling" the bike through the respective RPMs by rolling onto full throttle. ie... roll onto full throttle from 6,000 RPMs/ roll onto full throttle from 9,000 RPMs. Approach the idle as outlined below.

NOTE: DO NOT simply survey for jetting settings and expect to drop in parts. That will not work. You CANNOT properly jet from arbitrary settings. You MUST start from stock, addressing each area one at a time. Hence, this will take the better part of a day/couple of days if you want it done right.

[edit]Step 1: Find the proper main jet.
Start from the stock jet and needle height, and increase the main jet size by ONE SIZE at a time, until you feel the upper too rich. Then back up to the previous size. Please note that the amount of gas passed by the main jet increases exponentially with main jet size, as the circumference of a circle increases exponentially with diameter! What that means is that the difference between jet sizes is not equal.

Example:

~Start from stock.

~#105=Way too lean. Bike won't rev past 6K RPMs.

~#108=Bike revs to redline, but sputters at high RPMs.

~#110=Bike pulls hard to redline.

~#114=Bike bogs at high RPMs.

~Go back one size to #110s.

Symptoms:

LEAN = Stuttering. Runs better when bike is hot. White plugs.

RICH = Bogging. Runs better when bike is cold. Black plugs.

[edit]Step 2: Find the proper needle height.
Start from the tuned jet that you decided on in step 1. Use the stock needle height, and keep raising the needles by adding washers. If it runs better with more washers, then, when you get to about 4, go up a size on the main jets and start with the stock needle height again.

Even after you get the main jet correct, you will often end up with a midrange stumble at 5k-6k rpm. This has little to do with main jet size. You can take care of it by adjusting the needle height. Lower the needle until you get a mid-range stumble, then raise it by 1 washer at a time until you get rid of the stumble.

Symptoms:

LEAN = Stuttering. Runs better when bike is hot. White plugs.

RICH = Bogging. Runs better when bike is cold. Black plugs.

[edit]Step 3: Find the proper idle mixture.
Find a short (2" or less) screwdriver or driver bit and adjust the mixture screws with the carb on the bike and the bike running. Turning the screws IN decreases the amount of gas. Turning the screws OUT increases the amount of gas.

Symptoms:

LEAN = Blipping throttle causes the RPMs to rise, hang for a moment, then drop back down.

RICH = Blipping throttle causes the RPMs to rise, drop down below the idle speed setting, and the rise back up.

[edit]Conclusions
Ideally, you would follow these steps, examining the plugs after each step. However, in the absence of a dyno machine, it's not always possible to find a place where you can, for example, do several full throttle runs and immediately shut the bike down and examine the plugs, while doing carb adjustments on the spot!

It is advisable though, to monitor overall plug conditions after the jetting process. "Feeling" the bike will get you close, plug color can help you nail it. See the links on the Spark Plug page for information on plug color.
 

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Discussion Starter · #6 ·
i would guess it is a carb problem. i have similar problems with my bike and it turned out my carbs had some unnecessary dirt in them. i would assume that your carbs are clean being how you did the jets so many times so if its not that then maybe an adjustment problem. i dont claim to be a professional mechanic but that would be my 2 cents. hope this helps?
thanks pal.. well as i changed the jets so may times i would think the carbs ar pretty clean.. y ve chekled that everytime i open.. but im gonna put some clean carbuartor to let penetrate this night hope tomorrow helps =/ thanks for ur reply any way
 
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