The BlackBird not responding after 4,000 rpm

dahhbuzz · L Plate Warrior Joined: 05 Oct 2004 Karma :

Hi I have a 1997 Honda Blackbird with Carburettor. It moves ok on 1st gear. But from gears 2 - 6 when ever I hit about 4,000 rpm pls it begiuns to jerk and never passes 5000 rpm.
I have checked all the fuel lines, the jets nothing . I have used the brain box on another bike and it works fine, but when I re attached to my bike it was the same prob.

Can anyone help me with this

Thx

NickD · World Chat Champion Joined: 20 Aug 2004 Karma :

The carburated Blackbirds were noted for having a flat spot at around 4k, can you not pass through it at all?
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stryker · Brolly Dolly Joined: 30 Aug 2004 Karma :

Is your battery well charged? A power dip owing to flat bat or duff alternator can starve the electric ignition of the power it needs to spark.

MarJay · But it's British! Joined: 15 Sep 2003 Karma :

How long have you had the bike? If you have just bought it I would suggest checking to see if it is restricted to 33bhp!

Sounds silly but I reckon such a restriction might make the bike behave as you describe.

If you have had the bike a while, can you describe what lead to this loss of power?

Another possibility might be an air leak in the intake somewhere.
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British beauty: Triumph Street Triple R; Loony stroker: KR1S; Track fun: GSXR750 L1; Commuter Missile: GSX-S1000F; Cheap project: CBR900RR FireBlade
Remember kids, bikes aren't like lego. You can't easily take a part from one bike and then fit it to another.

dahhbuzz · L Plate Warrior Joined: 05 Oct 2004 Karma :

The bike was in an accident and was 'repaired' . Apparently I have been told that this is the 3rd Honda this is happening to by a friend of mine. All after crashes. Could this be a safety mechanism when a vital component has been damaged as even with a new carb the same prob still arises

Finglonga · World Chat Champion Joined: 27 Jul 2004 Karma :

Very very long shot.......
But is there a blockage in the fuel tank breather, as if there isn't enough air getting into the tank a vacuum will form and the engine will suffer from fuel starvation.
You can tell as If you open the tank after a ride the cap will hiss.
Like I said long shot.
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zzr_peak · Renault 5 Driver Joined: 24 Jun 2004 Karma :

i have the same problem with my kawasaki zzr 400 but it cuts out at 10,000 revs, and wont get round to 16,000

i have pretty much striped the whole;e thing, changes plugs, fule lines, about everything

i havent checked the tank breather (good idea)

and i have been told the problem can come from the ht leads where the join the caps. the can get corded and not make a strong enought spark, so.... chop half inch off and reattach the, worth a try.