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Discussion Starter · #1 ·
Please help,

I have a cbr900rr that is not going over 108mph at all. not jetted everything stock. I ride it on the freeway mostly. I use 91oct gas and service it more often than usual. just replaced the spark plugs,fuel pump, stator, regulator, chain, oil, fuel and air filters, clutch plates and went from stock lights to LED's. The bike runs smooth and it runs perfect on the street at lower speeds, I also checked the ventilation on the gas tank and is good. bypassed the clutch switch and the kickstand switch. I even checked the air level on the tires and it is to specs. (some funny guy suggested that). Please help...
 

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Discussion Starter · #3 ·
Nope, It was doing fine, this happened out of the blue. The top speed I could reach sometimes was 145mph.
 

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Heeza Y Zasch
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that's a rather meaty rear tire for the I-5 in San Diego! :eek:

Without knowing much more than what you've posted, I'd steer my troubleshooting toward the Fuel Pressure Regulator and/or cleaning the carbeurator(s). You stated you've changed the plugs... which ones are you running, and did you change the wires? Additionally, you could have a vacuum leak somewhere. Be sure to check all smaller rubber hoses, since in Socal they're prone to be weather-checked. Even the slightest leak can inhibit performance at any/all ranges.

Good luck, and keep us posted :thumb:
 

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that's a rather meaty rear tire for the I-5 in San Diego! :eek:

Agreed here, get ride of whatever that is on your rear rim!! It looks like, well, I can't even describe it! But I would guess 1 hot corner and you're gonna eat the pavement.

Without knowing much more than what you've posted, I'd steer my troubleshooting toward the Fuel Pressure Regulator and/or cleaning the carbeurator(s). You stated you've changed the plugs... which ones are you running, and did you change the wires? Additionally, you could have a vacuum leak somewhere. Be sure to check all smaller rubber hoses, since in Socal they're prone to be weather-checked. Even the slightest leak can inhibit performance at any/all ranges.

Good luck, and keep us posted :thumb:
Did you forget you have a 6th gear? :D

It seems you've changed a heck of a lot of parts recently. Was all that in response to the new low top speed issue?

How did you measure your speed?

Being a street fighter, how accurate is your speedo?

Will it run to redline in lower gears?

Lots of questions to answer.
 

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Forget getting over 108mph... your bloody fairings have run off!!!!! I would be searching for the chap that nicked your fairings first =)




Seriously though, I would guess fuel filter, pump, or a carb issue.. ^^ Doohan the "carb guru" has arrived to help you out just in time too =)
 
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Discussion Starter · #8 ·
that's a rather meaty rear tire for the I-5 in San Diego! :eek:

Without knowing much more than what you've posted, I'd steer my troubleshooting toward the Fuel Pressure Regulator and/or cleaning the carbeurator(s). You stated you've changed the plugs... which ones are you running, and did you change the wires? Additionally, you could have a vacuum leak somewhere. Be sure to check all smaller rubber hoses, since in Socal they're prone to be weather-checked. Even the slightest leak can inhibit performance at any/all ranges.

Good luck, and keep us posted :thumb:
I've checked al the hoses and they are all okay, I.m running k&n's and also new wires. Now, I'm failing to identify the fuel pressure regulator on my fireblade, would that be the pump that is positioned right bellow the main fuel valve?. When I have the bike running and put the valve on the off position it takes a few seconds and starts making a clicking noise, I'm asuming it is working well. :|
 

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Discussion Starter · #9 ·
Forget getting over 108mph... your bloody fairings have run off!!!!! I would be searching for the chap that nicked your fairings first =)




Seriously though, I would guess fuel filter, pump, or a carb issue.. ^^ Doohan the "carb guru" has arrived to help you out just in time too =)

New filter and new pump, the only thing I haven't done is the compression test and the carb cleaning. I only dumped a can of seafoam on the tank with a lil bit of gas and left it siting for a couple of hours, then started the engine and rode it few blocks and back. It ran smoother after I did that.:smile but still not getting over 108/110 mph like it used to:frown.
 

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Discussion Starter · #10 · (Edited)
Did you forget you have a 6th gear? :D

It seems you've changed a heck of a lot of parts recently. Was all that in response to the new low top speed issue?

How did you measure your speed?

Being a street fighter, how accurate is your speedo?

Will it run to redline in lower gears?

Lots of questions to answer.

1.- LOL

2.- I've replaced parts because they had to be replaced as they where old and worn, the only thing I did in response to this matter is a new pump and a can of seafoam on the tank. after this done it ran smoother but not faster.

3.- I removed the cluster and started using an application on my phone that works with GPS.

4.- Thinking that the app on my phone was giving me a wrong speed reading I attached the speedo cable and the cluster back to compare my phone against it and it changes by approximately 2 mph, the speedo shows 108 mph and the GPS 110/112mph (not that accurate but close enough).

5.- It does get to the redline on lower speeds.:smile
 

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Heeza Y Zasch
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I.m running k&n's and also new wires.
Running K&N what's? :idunno:

Now, I'm failing to identify the fuel pressure regulator on my fireblade, would that be the pump that is positioned right bellow the main fuel valve?. When I have the bike running and put the valve on the off position it takes a few seconds and starts making a clicking noise, I'm asuming it is working well. :|
Pardon me. Your carbureted Fireblade does not have an FPR. Excuse me for misleading you. That advice would be better suited for a machine with FI. I apologize.
 

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Fuel related, had to be. If it pulls hard to redline in 3rd but not 5th (for example), it's a fueling issue. My bet is crap in the carbs. Happens all the time, even to the cleanest carbs.

Get your bike up to temp, take a spray bottle of water and spray a stream of water on each header pipe. The water should "steam off" immediately. You'll know if you have a dead cylinder if the water trickles, or doesn't burn off instantly. That may help you narrow it down.

It might not show up at slower speeds, but once the engine is looking to keep you moving and wants more fuel it may be starving for it.

What is the symptom like? Is it like you're hitting redline at 108 mph? Or is it more the throttle is to the stop and it's just not revving out?
 

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Heeza Y Zasch
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Running K&N what's? :idunno:



Pardon me. Your carbureted Fireblade does not have an FPR. Excuse me for misleading you. That advice would be better suited for a machine with FI. I apologize.
really :idunno: when did they start making them?

I'd love to see a picture :hmm:
Imagine what kind of power you wouldn't be making by using them?
 

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Heeza Y Zasch
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I don't even know how to respond to you right now :rotfl:
 
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