Increase performance... needle... - Sportbike Forum: Sportbike Motorcycle Forums
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post #1 of 3 (permalink) Old 04-09-2001, 03:10 PM Thread Starter
Join Date: Mar 2001
Posts: 85
I have a ZXR 400 '92. And I the fuel used by the bike is excessive. I can go 160km on 11 litress.

What if I raise or lower the needle? Will it help?

I also wanna improve the performance. Will it improve the performance of the bike if I make the fuel mix better? Right now it is going too rich and I believe that is making the bike slower somehow. Am I right?

Please fill me in. I'm clueless. Thanks!
SwedieDN is offline  
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post #2 of 3 (permalink) Old 04-09-2001, 03:33 PM
Join Date: Jun 2000
Posts: 873

You are on the right track, but without an exhaust gas analyzer and a dyno, you are going to have a bit more of a difficult time zeroing in on the problem.

Nonetheless, i would drop the needles one notch, (may not be possible depending on where they are.. you may have to move clips or get adjustable needles) If you cannot drop the needles i would recommend dropping the main jet size by 2 or 3 (example: if you now have "105" main jets, change them to "102")

This will lean out your mixture and you should see a difference.

Performance MAY go up or it may go down.

Also, you should check your air filter, as a dirty air filter can cause similar problems and effectively richen up your final mixture.

This is all standard troubleshooting steps. Its hard to say exactly what the problem is with the limited info given.
GreenNinja is offline  
post #3 of 3 (permalink) Old 04-09-2001, 04:21 PM Thread Starter
Join Date: Mar 2001
Posts: 85
Please tell me what more info I can try getting.

Don't laugh now... I'm using women type socks for air filtering
If the "filter" has too much dirt/dust on it.. the fuel gets richer? or is it wise versa?

Just "Main jetsize" sounds like it is hard to reach.. I'm able to detach most stuff from tank to airfilter.. but then there is the air "suctions".. I've yet not passed any further than these on my own hand.
I did on my old RD 250.. adjusting the needles quite often...

I've got a manual from a '91 ZXR 400.. it should help me out somewhat.

(I'm swedish so excuse my use of "words". I hope you understand anyway)
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