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Hello bike lovers,

This is my 1st post so i will try to explain my issue as good as possible.

Last year i bought a CBR F4 based on specs. The bike runs perfect, no issues, the engine sounds perfect.

My issue is that the bike Tops around 245km/h and hesitates to go red line on 5th and 6th.

On 5th Gear it tops around 12k RPM and in 6th around 11k RPM.
What i did to solve the issue is:
-> Carbs were cleaned and adjusted at a local dealer (3 turns of air/fuel mixture)
-> New Iridium Plugs
-> Sport Air Filter
-> New Fuel Filter
-> After market exhaust

But with all the adjustments the problem still persists.
I saw plenty of recordings where F4 goes red line in 6th so i was wondering, is there something that limits the bike in 5th and 6th ?

In all gears except the above mentioned, the bike pulls very hard, rear wheel spins like crazy when hard accelerate.

Any ideas what can limit the bike ? Or maybe some aftermarket components that are rev limiting or not completely compatible ?

Thank you very much,
Alex
 

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You want a used bike to hit redline in 5/6 gears? For argument sake mind you, here is how I think this goes down to the wire.
a. The bike is used. I have the imaginary shop manual opened to the compression numbers.
b. The window reads a 147 to 228 psi minimum and maximum number. What is yours against the book?
c. The bike will not top out at 140 kind of psi numbers. The 228 kind of compression to get there to redline can.
d. The short list is I first check compression of an old dog trying an old trick a puppy could do when fresh and new.
 

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Hello bike lovers,

This is my 1st post so i will try to explain my issue as good as possible.

Last year i bought a CBR F4 based on specs. The bike runs perfect, no issues, the engine sounds perfect.

My issue is that the bike Tops around 245km/h and hesitates to go red line on 5th and 6th.

On 5th Gear it tops around 12k RPM and in 6th around 11k RPM.
What i did to solve the issue is:
-> Carbs were cleaned and adjusted at a local dealer (3 turns of air/fuel mixture)
-> New Iridium Plugs
-> Sport Air Filter
-> New Fuel Filter
-> After market exhaust

But with all the adjustments the problem still persists.
I saw plenty of recordings where F4 goes red line in 6th so i was wondering, is there something that limits the bike in 5th and 6th ?

In all gears except the above mentioned, the bike pulls very hard, rear wheel spins like crazy when hard accelerate.

Any ideas what can limit the bike ? Or maybe some aftermarket components that are rev limiting or not completely compatible ?

Thank you very much,
Alex
Your compression is likely just fine. Catch answers low compression to every post on this forum. Don't be alarmed.



You didn't mention a jet kit or larger main jet to adjust a richer setting for the low restriction exhaust and air filter. When do you mean by adjusted? If you can't push more in 5th and 6th, you likely need more fuel to do it, and that is installing a bigger main jet than you have. You're running too lean. Parts start to get really hot in such an instance too. Holes in pistons, burned valves....
 

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"Your compression is likely just fine" is when guys like this show up for speed events is easy trophy taking call it.

One more time. Base tune is bone stock.
Performance a/c element = Lost 2 hp at the top end... is one model brand example I am familiar with. I apply this variable to any other brand I go up against factory formulas and teams of engineers specializing in areas of expertise.

Performance pipe = Some lose hp to the base pipe.
Sport a/c contraption = Formula at the factory and velocity theory, not someone thinks [more air] is that thinktank of a part being made = hp is where from base?
Jetting = And what time of the day, the sensors on modern bikes that have that built in, not me looking at the air temp, atmo pressure, humidity index to jet ~ My 6th gear.

:idunno: Are we on the same page yet?

Signed,
NOLTT (no one likes turtle tuning)
 

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Discussion Starter #5
Dear Catch22,

Instead of complaining, why we don't try to come up with ideas / solutions...
There are plenty of F4 owners that can do red line in 5th and 6th in all the recent years like 2014 / 2015 and even 2016
Maybe you should try to write in a manner that every one can understand and read what you are actually typing.
My eyes are bleeding every time i read something from you.

@1926
I have the Stock Carburetor, stock jetkits and adjusted like in the manual.
When i got the bike it was a 2.5 turns of air/fuel mixture (richer) and it was still topping at 240-245
Now with all the adjustments mentioned, the bike tops way much faster but still stops at 245
So, you are recommending me the Stage 1 DynoJet Kit ?
 

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with the after market AF kit and exhaust, yes, you will need to look at changing the jets. either Dinojet stage 1 or other. any time you change the amount of air you are feeding it and/or change the speed at which the exhaust exits (AKA back pressure) you will need to balance the AF mixture entering the cylinders. in FI bikes this is controlled by the mapping, in a carbed bike you need to look at jet size.
 

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with the after market AF kit and exhaust, yes, you will need to look at changing the jets. either Dinojet stage 1 or other.
If you research "other" than stage 1 with only pipe and filter, they don't fit this application and would make things actually worse in drivability.
 

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Dear Catch22,

Instead of complaining, why we don't try to come up with ideas/ solutions...
Dude, you are complaining about screwing up your bike and I'm trying to get to the bottom of it. I don't chase my tail like a squid city cyclist on line. I told you the first clue and you ignored the basics. 'Not my bike' as they say.

There are plenty of F4 owners that can do red line in 5th and 6th in all the recent years like 2014 / 2015 and even 2016
Fresh as fresh can be. And your burned out year is? Clue #2. And it's burnt out until you come up with the cold hard numbers.

Maybe you should try to write in a manner that every one can understand and read what you are actually typing.
Maybe I better bail out of this one is going nowhere without... never mind.

My eyes are bleeding every time i read something from you.
I could write the book of just the quotes I get someone reads the catch is make you bleed from head to toe. I just start at the eyes LOL


Signed,
and I'm done wit dis one
 

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"My eyes are bleeding every time i read something from you."
Good call ulquiorra4.

I could write the book of just the quotes I get someone reads the catch is make you bleed from head to toe. I just start at the eyes LOL
:rotfl::rotfl: Dr. Seuss taking a compression reading, "One stroke, two stroke, red stroke, blue stroke" is what this does sound like.
 
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