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Hi all,

My boyfriend has been having a few problems with his blade.
It is a '98 CBR900RR completely standard including exhaust.
There is a flat spot between 5-6k revs is this normal?
Is there anything he can do to resolve it or make it less pronounced.

Any help appreciated.

Thanks
Caz
 

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Sounds pretty standard :), especially if it has same features under 3k rpm as well

Get Dyno time and start testing- then you have lots of different possibilities.
 

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Sounds pretty standard. I also found that I was getting one in right before the HTEC fully opened at 7000 when in the 75->100% throttle range.

If there is PCIII aboard some dyno tweaking should help resolve it.
 

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Holeshot, she's talking about a carbureted 98.  

The answer is that it may be common on that bike (I dunno), but it means there is a problem with the fueling.  Is the air filter clean?  If it is, it could mean the jetting and/or airscrew is out of adjustment.

Also, leaving off a vaccuum line, or not installing the airbox properly could cause a flatspot.
 

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I read in a book on the history of the Fireblade that at about 5500 RPM the certification testing of the noise level for the bike is undertaken.

Thus the manufacturer 'de-tunes' the bike in this range.

On my 98 Blade in Australia the noise compliant plate states 5500 RPM.

Apparently you can tune this flat spot out.
 

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Oldone : I read in a book on the history of the Fireblade that at about 5500 RPM the certification testing of the noise level for the bike is undertaken.

Thus the manufacturer 'de-tunes' the bike in this range.

On my 98 Blade in Australia the noise compliant plate states 5500 RPM.

Apparently you can tune this flat spot out.
2 new members in thread


Dynojet make carby kits for most bikes, I had 1 in my 94 blade, get 1 it should make the carbies a lot closer to being perfect, although they do have to be fine tuned.
 

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Thanks for the welcome Ratter, although I have been hanging around for a few months, but not contributing much.

Actually the 5500 RPM I mentioned is actually 5250 RPM.

Makes you wonder why they set these figures.

The book I refered to is Honda CBR900RR by Rob Simmonds, if anyone is interested.

Had it a couple of weeks but have basically only looked at the pictures
 

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Holeshot : Quote (luvtolean @ June 02 2003, 9:03am)Holeshot, she's talking about a carbureted 98.  

I'll crawl back into my cave now....
 

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I have a somewhat larger flat spot, and it seems to be stuttering hard from 6200/6500 till 7200/7700 and it isn't consistant. But I am still have to go through some basics, the bike has been sitting for a while. Plugs, carbs, and broke back in, then I will repost :D
 

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When you say flat-spot are you saying that the bike hesitates or that it seems to lack the desired power during the specific RPM range mentioned?

I don't have a flat spot. My bike pulls hard from the low revs all the way to Red-Line. (I'm also far from stock.)
Check the Air-Filter, change the plugs if it's been a while, and clean the carbs. It might even help to do a rebuild.
 
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