Want to Jet my Carbs for Full Exhaust?

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usmc84

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Hi All,
New to the site and thought you guys would know whats the best Jet Kit out there for a Full Yok. Exhaust on a 2004 FZ1. I was thinkning of installing a K&N air filter too.
Bought the bike used a couple weeks ago and it seems to be throwing a lot of heat of the headers so not sure if a jet kit was ever done to richen things up a bit.
Any advice would be appreciated.
:sport12:
Almost forgot...the headers have a lot of Yellowing have way up, almost to the carbon exhaust.
 
Jetting wouldn't be a bad idea... don't waste your money on a jet kit.

If you're below 2000ft of elevation, go get 4 127.5 main jets, if above 2000, 125's. If above about 4000, 122.5..

Replace the stock 130/132.5 mains with one of the above, turn the air screws 3 turns - 3.5 turns out.

Go to Radio Shack and get a package of "Circuit Board spacers".(They're electrical Washers) They measure out at .5mm. Put 1 under each needle to raise needle height.

That's the jet kit that you'd pay $150 for.


Then, to the airbox. Take off the air-box lid, drill a 1" hole in the top of it. Flip the cover over and remove the 1/2 of the snorkle facing the carbs.... Replace stock filter with K&N and replace cover.

While you've got the carbs off, that'd be a good time to "port" the intake boots. Basically, the boots come with a bunch of extra rubber on the inside that effectively shrinks the size of the intake.... with the carbs off, you can stick your finger in the boots and feel that they don't mate up cleanly to the intake ports on the engine.... You take a dremel and fix this... I can give more detailed directions if needed.
 
Thanks!!!

Thanks for the info. I'll go purchase the materials you described and let you know how i make out. I'm sure i'll need some more advice as I go along.
Thanks again.
 
raising the needles?

what do you think of ivans reply on his site:

" Raising the needle does not help because the throttle plates have not been open far enough to expose the needle circuit during light throttle cruise. The result is surging and buzzing that cannot be eliminated without modifications to this circuit."
 
I'd rather not say what I think about Ivan.

But what I will say is that on the dozen of so FZ's I've jetted, raising the needles works like a charm, and does not cause any surging or buzzing.
 
va_rider said:
Jetting wouldn't be a bad idea... don't waste your money on a jet kit.

If you're below 2000ft of elevation, go get 4 127.5 main jets, if above 2000, 125's. If above about 4000, 122.5..

Replace the stock 130/132.5 mains with one of the above, turn the air screws 3 turns - 3.5 turns out.

Go to Radio Shack and get a package of \"Circuit Board spacers\".(They're electrical Washers) They measure out at .5mm. Put 1 under each needle to raise needle height.

That's the jet kit that you'd pay $150 for.


Then, to the airbox. Take off the air-box lid, drill a 1\" hole in the top of it. Flip the cover over and remove the 1/2 of the snorkle facing the carbs.... Replace stock filter with K&N and replace cover.

While you've got the carbs off, that'd be a good time to \"port\" the intake boots. Basically, the boots come with a bunch of extra rubber on the inside that effectively shrinks the size of the intake.... with the carbs off, you can stick your finger in the boots and feel that they don't mate up cleanly to the intake ports on the engine.... You take a dremel and fix this... I can give more detailed directions if needed.
Click to expand...
I take it that the stock jetting is on the rich side as far as the main jets are concerned??
Why does the factory use two different size mains and should you rejet with two different size mains?
What do you think of removing the complete airbox and running K&Ns on each carb? We used to do this back in the 70s and 80s on the Kawasaki's. I noticed on Holeshots site that his stage two jet kit if set up for complete airbox removal.

I just purchased a 2005 FZ with only 1600 miles on it and am looking at how to best mod it.

Thanks!
 
yes... in stock configuration, jetting is a bit too rich...

as far as removing the airbox and going with pod filters... no significant gains have been seen by using pod filters.... however, there are gains to be had from modifying the air-box and porting the intake boots....

throttle response can also be crisped up by drilling the 2 holes next to the needle on the slides...
 
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