I have a 1991 CBR1000F that has no top end power. The Nevada desert of the Reno area is great for trying to find out your top end speed. I get my CBR into 6th gear and it will not go over 6,500rpms. That is about 125 mph, which is not slow, but is not a super bike quality speed. I checked the petcock flow, which is good (vacuum diaphram is good). I checked the tank screens (primary and reserve), which are good (clean and look great). The tank is perfect (no vapor lock or air vent problem). Plugs are new and gapped right. Vacuum hoses are all looking great and the air filter is new. Wheels roll great when off the ground and spun by hand. New chain and sprocket. No brake pad drag and no bearing issues. In 5th gear, I can get it up to 8,000 rpm, but it takes a long time to get there, then when I shift to 6th gear, the motor boggs down back to 6,500 rpm. Things I still need to check are the valves (clearance and leakage) and the compression of the cylinders. The bike idles great and runs up to 100 mph just fine, then slow going up to 125 mph. What do you all think is going on???? I have owned and worked on my own bikes since 1974, but this is my first CBR1000F so there may be something I am missing. Honda shop said they never heard of the problem and think that I should run the rpms up to 9,000 before shifting to 6th and see if the bike boggs down. Any clues, suggestions, ideas would be helpful. Thanks all
Oh, forgot to mention, I also have a 97 Suzuki TL1000S that kills my CBR in speed and "get up and go power." My BMW 94 R1100RS out performes my CBR and that is bad for Honda.

 

The altitude is 4,500 to 5,000 foot level. Almost a mile high in altitude. The air is thin so are you thinking the bike is running "fat" or heavy on the fuel side? I will take it out on a "Dark desert highway with the cool wind in my hair" (Hotel California by the Eagles) and try the old way of getting it up to speed, rolling off the throttle, punch the throttle and see the results. If it boggs, then it is too rich. If it coughs, then it is too lean. If I let of the throttle a little and it speeds up, then it is too lean. That's what we call a "Nevada Dyno test" in this area.

 

Are you sure you are twisting the correct side of the handle bars ? LOL
Mate .. you obviously have an issue to deal with ..
My 89 near climbs out of its own skin getting to 125 ..
You need to find out more about what has been done to her ..
It could be many things causing the trouble.. jets ? fuel ? electrical ?

For us to have any ideas , we need to know a little more ..
Have you altered the carbs at all ?
What pipes are on her ?
What type of air filter are you running ?
What fuel are you running ?
Does she red line strong , with ease , in the first 4 gears ?

mate, all that above is only bad for YOUR CBR1000F...
get her going right and those machines will have to fight to stay with you !!

 

Swisherred, I just bought the bike a few months ago and do not think the jets were changed. BUT, I do know this is a California bike and all California bikes run lean until rejetted. So, the former owners (she may of been ridden by many, poor girl) may have rejetted the California jets to make it run richer. Then, I bought it here in Nevada and since the air is thin, she would run even richer. I was hoping not to have to get into the carb jetting. I am use to KZ1300s, so a carb rejet is not a problem, but the time will have to be made for some further investigation on the carb side of things.
Lucky for me, it is raining (yes, 7 inches a year is all in this area) and snowing outside tonight so I will have the rest of the weekend to dismantle the carbs. Does anyone know the proper jet size for a 1991 CBR1000F carb at 5,000 feet above sea level????

 

CBRclassic, you crack me up!!! I like your postings
As far as I know, there have been no upgrades on this bike. Stock everything. I have not gotten into the carbs to see if they have been rejetted so I will look into that this weekend. Air filter is a Uni foam filter with oil on it so it catches the dirt. It is new. Pipes are stock and NOT punched out or messed with. Tires are new so rolling issues are not a problem.
I currently have the tank off and have checked all the vacuum lines (I have a hand held vacuum tester with a gauge on it to test the air vacuum modules).
I did look up the CBR1000F on Google for a top end spec list and found that up to the 1992 model, the top end is 146 mph and the later years go, I believe 165 mph. It may be that at this altitude on a 60,000 mile bike, all I can expect is about 130 mph or so. What do you think???
My TL1000S has me wearing a second pair of underies when I come out of a corner and hammer the throttle!!! Two filters are better than one when you hammer a TL out of a corner!

 

I think Pete is on to something regarding the restrictors if she has never been raped LOL

I am glad you like my posting mate ...
... that's at least something positive ...LOL

Your Un foiam filter ?? what oil are you running in it ? light ? or heavy ?
BTW- hey Pete , do they come std with a Uni foam or are the 91's an element std?

I know some bikes do not like those filters when, or if they are over oiled or the wrong heavy oil is used on them


A BIG +1 .... amen and all that stuff to that statement Pete