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Hi All
I'm working on my 1990 ZX7 H2 and having a problem with my carbs.
My symptons are as follows
1 Bike starts and idles fine.
2 Bike revs from idle to redline fine
3 Bike completely falls on its face between 8K-12K under load.
What I have done
1 Full Muzzty exhaust
2 Dynojet Stage 1 kit
3 Needles are on the bottom clip(seems to work best)
4 Using the DJ118 jet(bigger of the 2 provided)
One of my questions is that the stock 128 jet that came out of carb looks like it has a larger hole in the center.If that is the case am I just not getting enough fuel?
Thanks for the help
 

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The Cruising Gunsmith
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1,459 Posts
Speaking of jetting: in my thread that nobody answered on, I have also what appearts to be a jet problem:

I installed a 2-1 MAC header on my 750 Twin and notice it goes power "flat" as I rev to about the 4500 - 5000 range.

The stock main jet is 125, I had a 130 in it..... went to 135 and it feels maybe a bit stronger.

Do I need to go to a bigger main?

Under hard acceleration: low rpm pull is very strong, runs well up to about 4000.... but then starts pooping out.
 

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Are your needle jets in the stock position? If so, raise them a notch. If they do not have grooves get flat washers to raise them up; put the washer under the e-clip.
 

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The Cruising Gunsmith
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Are your needle jets in the stock position? If so, raise them a notch. If they do not have grooves get flat washers to raise them up; put the washer under the e-clip.
They are presently in the stock (center) position.

I thought about raising them up, but in the factory manual it said that when the floats are fully up (wide open throttle) the needles don't limit the amount of fuel any more, only the diameter of the main jet does.

When I accelerate hard (wide open) it still feels like it runs out of power at about 4500 RPM.

I'm thinking I still don't have enough gas from the main.
 

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Navy Vet Search & Rescue
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4 Using the DJ118 jet(bigger of the 2 provided)
One of my questions is that the stock 128 jet that came out of carb looks like it has a larger hole in the center.If that is the case am I just not getting enough fuel?
Thanks for the help
According to Kawasaki.com the bike came with a 128 main.
 

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Navy Vet Search & Rescue
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8,842 Posts
They are presently in the stock (center) position.

I thought about raising them up, but in the factory manual it said that when the floats are fully up (wide open throttle) the needles don't limit the amount of fuel any more, only the diameter of the main jet does.

When I accelerate hard (wide open) it still feels like it runs out of power at about 4500 RPM.

I'm thinking I still don't have enough gas from the main.
Heres a little blurb from a carb tune site. You can take it or leave it but it sure sounds like you have midrange problems to me.
To get the best power at full throttle / 5k-7k rpm, adjust the needle height,
 

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The Cruising Gunsmith
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Heres a little blurb from a carb tune site. You can take it or leave it but it sure sounds like you have midrange problems to me.
It does sound like the problem I have. maybe I will try raising the needles and going to the lowest notch with the clip.

I ordered some larger main jets so I will probably try fiddling with the needle height and the main jet size a bit.

Thanks for the info.
 

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Just raise it one notch first, that's probably all you will need to do. Don't raise the needle AND put larger mains in at once. It's easier to sort out jetting when you deal with one variable at a time.
 
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