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post #1 of 21 (permalink) Old 05-15-2007, 11:12 PM Thread Starter
 
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High RPM Miss?

Ok guys I just finished installing my Jet kit and K&N on my 95 ZX6R. It runs so much better! It might still be a little bit rich on the low and mid, I'm thinking about moving the Needle down one more notch and turning the idle air screws in 1/2 turn.

My question is that it runs great on the Upper end all the way until 12,000 rpm then it has a miss or stumble then pulls hard again to 14,000 rpm (redline). What can be the cause of this? I'm kinda clueless

Thanks guys
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post #2 of 21 (permalink) Old 05-16-2007, 09:59 AM
 
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Maybe your clutch is about to eat it.
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post #3 of 21 (permalink) Old 05-16-2007, 03:20 PM
 
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Maybe your clutch is about to eat it.
I doubt that....


but it sounds like you mixture might not be perfect...plus you might want to check the spark plugs...

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post #4 of 21 (permalink) Old 05-16-2007, 06:41 PM
 
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I doubt that....


but it sounds like you mixture might not be perfect...plus you might want to check the spark plugs...
Maybe his flux capacitor is bad.
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post #5 of 21 (permalink) Old 05-16-2007, 06:50 PM Thread Starter
 
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I doubt that....


but it sounds like you mixture might not be perfect...plus you might want to check the spark plugs...
Thanks I was thinking that I might check the plugs very soon! As for the clutch I think it is getting close to needing to be replaced. I have noticed a bit more slipping when launching hard. But its not the cause of my problem I'm talking about. It doesnt rev up like its slipping when I hit the said miss at 12k. Thanks for the ideas!
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post #6 of 21 (permalink) Old 05-16-2007, 06:54 PM
 
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So your bike is stumbling around 12k, and then when it gets going again it shoots up to 14k? def sounds like a mixture problem. back to the jets.
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post #7 of 21 (permalink) Old 05-16-2007, 06:56 PM
 
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So your bike is stumbling around 12k, and then when it gets going again it shoots up to 14k? def sounds like a mixture problem. back to the jets.

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post #8 of 21 (permalink) Old 05-16-2007, 07:00 PM Thread Starter
 
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So your bike is stumbling around 12k, and then when it gets going again it shoots up to 14k? def sounds like a mixture problem. back to the jets.
It just has one miss and then pulls hard again. It's alot like my Turbo Eclipse I had the would hit fuel cut when the boost was just a tad high. It runs great from 6k to 12k then miss for a quick fraction of a sec the great to 14k. Maybe I'm unclear on the jetting but If it pulls great till then doesn't that mean that the main jet is very close? and thats the only adjustment that you can make for high RPM WOT right?

I was thinking it was something other than fuel.
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post #9 of 21 (permalink) Old 05-16-2007, 07:02 PM
 
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It just has one miss and then pulls hard again. It's alot like my Turbo Eclipse I had the would hit fuel cut when the boost was just a tad high. It runs great from 6k to 12k then miss for a quick fraction of a sec the great to 14k. Maybe I'm unclear on the jetting but If it pulls great till then doesn't that mean that the main jet is very close? and thats the only adjustment that you can make for high RPM WOT right?

I was thinking it was something other than fuel.
I would lean to the mixture its self.....but check the plugs still.

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post #10 of 21 (permalink) Old 05-16-2007, 07:05 PM Thread Starter
 
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I would lean to the plugs still.
What about gapping them a few thou tighter? Would this do anything?
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post #11 of 21 (permalink) Old 05-16-2007, 07:07 PM
 
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what i was thinking is the mixture is too lean at 12k, and the cylindes arent fireing properly, but more fuel is pulled in the mixture gets a lot richer... not sure if it would happen that way but it would explain the miss and then sudden boost.
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post #12 of 21 (permalink) Old 05-16-2007, 07:09 PM
 
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eww, or maybe your float isnt letting fuel into the chamber at that RPM.
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post #13 of 21 (permalink) Old 05-16-2007, 07:35 PM
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What about gapping them a few thou tighter? Would this do anything?
Gapping tighter would make the spark "colder" a larger gap would make it "hotter."

Hotter would fix your rich low end. What's it smell like in high revs? Any smoke at all (blue being fuel-rich)?
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post #14 of 21 (permalink) Old 05-16-2007, 11:09 PM
 
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Buy new plugs, take out the old ones, keep them in order, tell us what they look like, or better, post a picture of them.
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post #15 of 21 (permalink) Old 05-16-2007, 11:59 PM
 
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Buy new plugs, take out the old ones, keep them in order, tell us what they look like, or better, post a picture of them.
what he said...
plus, sync the carbs and pop out the mixture plug and read the dynojet manual on how many half turns from close. the miss is often referred to a flat spot.

also, what stage kit is it? are you still running stock exhaust?
the best way to jet a bike is on a dyno.

-a|ex
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post #16 of 21 (permalink) Old 05-17-2007, 08:01 AM Thread Starter
 
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Buy new plugs, take out the old ones, keep them in order, tell us what they look like, or better, post a picture of them.
Will do as soon as payday gets here! Thanks
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post #17 of 21 (permalink) Old 05-17-2007, 08:05 AM Thread Starter
 
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what he said...
plus, sync the carbs and pop out the mixture plug and read the dynojet manual on how many half turns from close. the miss is often referred to a flat spot.

also, what stage kit is it? are you still running stock exhaust?
the best way to jet a bike is on a dyno.

-a|ex
Carbs have been syncronized when I installed the kit. The Idle Mixture screw is set 3 full turns out from closed as in Dynojet instructions.

Flat spot thats the discription I was looking for! Thanks

It's a stage 1 kit. Stock head pipe with a bolt on Muzzy can.

I wish I had access to a dyno at this time!

Thanks again everyone!
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post #18 of 21 (permalink) Old 05-17-2007, 08:09 AM Thread Starter
 
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Originally Posted by Phenix_Rider View Post
Gapping tighter would make the spark "colder" a larger gap would make it "hotter."

Hotter would fix your rich low end. What's it smell like in high revs? Any smoke at all (blue being fuel-rich)?
Excelent information! Thanks

It revs fine sitting on the stand. It only does it when the engine is under load. Good thinking though!
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post #19 of 21 (permalink) Old 05-17-2007, 02:50 PM
 
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The Idle Mixture screw is set 3 full turns out from closed as in Dynojet instructions
the main fuel mixture screw is usually sealed (bottom of the carbs). a drill is needed to pop the seal. is that the mixture screw you turned? i think it's usually 5 half turns out from closed.

-a|ex
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post #20 of 21 (permalink) Old 05-17-2007, 02:58 PM
 
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if you have a set of smaller main jets, try that.

-a|ex
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