CBR600 Special HELP

[TonyW650]

hey guys sorry its not a storm., apologising in advance just need some pointers.
I did ask a question about this bike a while back and think Lloydie gave me some directions.
its a CBR600 FL engine cbr 400, its all up and running now and mot's and tax's but
you pull away and the engine wont or dont want to seem to rev out past say 7-8000 rpm
1st, 2nd, 3rd, 4th it will spin up, but slowly and then hits say 7-8k rpm and dont want to go
slip it into 5th or 6th and there is nothing there no pull no guts, like its hitting a wall.

she reckon its hitting a wall at about 100mph.
I still think it needs a jet kit to run properly but, it dont appear to be running lean at low rpm unless its going lean as the revs rise, I havent ridden it and to be honest dont want to.
but it winds up from following her ok but she say its just not exciting the way it pulls and then it just seems to stop dead, yet you can blip the throttle happily as Ive heard here do with it in nuetral and it goes right up.
so what keeps going through my mind, does it need jetting up, is the fuel pump supplying enough fuel, is the inline fuel filter resticting the flow at higher rpm.
one thing I did notice the other day is her airbox is well empty, it has the filter buy no velocity stacks in there its like the rubber trumpets have been remove, could this cause problems.
any help would be great fully recieved

[VTRDark]

By the sounds of it it's either running lean on top or got a blockage. It could possibly need re-jetting. Has it got an aftermarket exhaust on? If I was you I would at least give it a good tune up, take carbs off give them a good clean through, make a note of the jets that are in there, clean/replace the air filter, sync carbs and put stacks in. I'm not sure if not having the stacks in will cause this, but it's certainly not going to help the airflow.

(:-})

[lloydie]

Put some stacks in there it will help .
What have you done to the air box?
And which electrics did you use 4 or the 6 ?

[TonyW650]

its not my bike and Ive done more work on it for here lol
but anyway, its got the 600 fl loom and ecu all fitted
I'm not getting into rejetting as its not my bike and after doing all the electrics, im not rejetting it for her aswell.
its running a D&D can on standard headers
all the previous owner has done is make the tunnel where the throttle cables go thought a bit deeper., thats it.
the reason there is no stacks is what they did was machine a a plate which was bolted to the carbs and the the airbox was bolted down to the plate, so no rubbers or stacks.

Ive tried to tell here to cut her losses, told her it needs the stacks and possibly rejetting, 3-4 weeks ago but she didnt listen to me than and know wants to sell it but wants 500 quid, i reckon its only worth 150 at most.
how much is it really worth, no front fairing, single seat tail unit cheap indicators, rads been bodged to fit, so have the hoses, speedo dont work properly aftermarket one, header pipes are rusty, tank and tail init need respraing. its got a mot and tax lol

[lloydie]

Is it the 400 air box been made to fit ?
If it is then the intake holes are not big enough .
When I did mine I used the 600 carbs and air box lower . I made my own lid with 2 3" holes in and it pulled to the red line without hesitation on standard jets .

If your looking to sell it join 400graybike

I paid £10 for mine (cbr400rr) from a friend lol I would do you the same deal lol.
When they are fully sorted they are worth a grand .
But unfinished eBay is the best bet to get a good price for it .

[VTRDark]

Sounds like an abomination. Get her to sell it and buy a Storm, we could do with some more biker chicks on here.

(:-})

[lloydie]

Sounds like an abomination. Get her to sell it and buy a Storm, we could do with some more biker chicks on here.

(:-})

why you getting fed up will all the attention Carla

[VTRDark]

(:-})

[TonyW650]

the part of the airbox where the inlet stacks would be has been removed and the airbox lower with filter has been bolted straight to a alloy plate thats bolted to the carbs and then the standard top of airbox has been refitted
I have a feeling from looking at photos on the net it may be a 400 airbox not a 600.
would the volume of the box make any differance, I know that stacks will as its all to do with the way air moves into the carbs

[lloydie]

The volume will be ok but you need the correct size inlet holes to get just the right amount of air in .
To much and it won't rev to little and it won't rev .
And if it's getting ram air it won't ride to the red line .
It took me weeks to get it right on mine

[TonyW650]

I see where your going Lloydie, all shes got is the base of the air box bolted to the alloy plate and the the filter on the base and then the airbox lid, the lower section with the stacks goisnt there, and nor are the air box inlet scoops from the front.
the previous owner that started the conversion binned the base of the air boxs and velocity stacks, its for want of a better description a a gutted airbox.
I dont think its getting enough air and with no stacks in there the air is to disturbed to swirl properly into the carbs