hesitation after hard braking

gazb · Post by **gazb** » Sun Jun 20, 2004 11:16 pm

i have an annoying problem that i hope someone has the answer to.
after hard braking for a corner, when i get back on the throttle my vtr hesitates as if it is starved of fuel, which makes hard riding a little tricky!! this only happens after braking hard, at all other times the bike behaves perfectly normaly. please does anybody know the cause of this as its getting frustrating

MDJ · Post by **MDJ** » Mon Jun 21, 2004 10:24 am

Ditto mine does that when I really drop anchor from 80+ Then fuel starvation sounding and feeling like an inline 4 firing on 3 .

Ideas anyone? CBR6 fuel pump upgrade maybe?

Pete.L · Post by **Pete.L** » Mon Jun 21, 2004 11:29 am

Gazb&MDJ
It could be either. There is a cbr600 mod which will sort it if it's starvation. Mainly track racing this is required for or it might be because so much fuel is flowing through the carb at high revs the float bowls allow too much fuel past befor they can recover.
I've also had a carb slide sticking open and this gives the same affect or if it only happens around approx 3.5 to 4.5k rpm have you a K&N filter fitted?
Any more info?
Someone here's bound to have an Idea with a few more clues

Pete.l

MDJ · Post by **MDJ** » Mon Jun 21, 2004 12:03 pm

With mine it happens when having braked from 80+ with full on racing gearchanges reving fairly hard (8-10K revs) and then it just doesn't pick back up properly from low/mid range for just a couple of seconds.
This only happens as I say when I'm administering great pain and sufferring to the bike riding very hard and on the brakes so hard the front is squealing as it locks up momentarily and re grips and locks........

eg the kind of braking you do when you realise theres a speed camera too near.....

Pete.L · Post by **Pete.L** » Mon Jun 21, 2004 12:57 pm

Mdj said

the kind of braking you do when you realise theres a speed camera too near.....

Oh! That kind of breaking

Now we all understand

Are you on std pipes, after market replacement, race pipes? What kind of filter? Is it dyno jetted? ect

Pete.l
Give us all the info you can. I'd hate to say "Hmm,yes. They do that sometimes"

MDJ · Post by **MDJ** » Mon Jun 21, 2004 2:00 pm

Pete,
my bike has been Dyno jetted, micron cans, k&N filter, drilled carb slides.

Pete.L · Post by **Pete.L** » Mon Jun 21, 2004 4:07 pm

Mdj,
there are a couple of ways to tackle the problem.
1st you need to ascertain whether the bike is running rich or weak.
The easiest way would be to get it back on the dyno and recreate the problem there. They can monitor the mixture and let you know whats happening.
Or 2nd, you could tape a couple of strips of gaffertape over the air filter inside the air box. This would make the bike run richer. If you make the problem worse then you are probably too rich already, if it improves it you are running slightly lean.
If the stumble does'nt happen with the tape try raising the needles 1/2 or 1 groove if the tape has made the problem worse try lowering by the same amount to weaken the mixture.
Thats all I can think of right now unless someone else has any idea's and here's the link to the fuel pump if nothing else works what have you got to loose. http://www.abercon.co.uk/~neilr/faq_cbr_fpump.htm

Pete.l

MDJ · Post by **MDJ** » Mon Jun 21, 2004 4:29 pm

Thanks Pete your advice is greatly valued..

gazb · Post by **gazb** » Mon Jun 21, 2004 6:21 pm

cheers, i will try what you suggest and let you know

vtrsteve · Post by **vtrsteve** » Mon Jun 21, 2004 7:50 pm

Chaps, this is an easy fix!!

Take the two carb breather pipes out from the brackets either side under the tank and let them hang straight down instead of pointing into the void between the carbs - simple as that!!

You can do it without taking anything off the bike as well so a simple 30 secs to sort.

I had exactly the same symptoms of fuel starvation after heavy braking at donny, this cured it straight away.

Steve

Pete.L · Post by **Pete.L** » Tue Jun 22, 2004 7:57 am

Thats right,
Also helps cure if you have been riding hard and then come to a stop ie junction,sheep in the road ect, that pop and stop of the engine

Pete.l

MDJ · Post by **MDJ** » Tue Jun 22, 2004 9:31 am

Waaa! sound too easy to be true! nice

I'll try it tonight... thanks steve

Stormin Ben · Post by **Stormin Ben** » Tue Jun 22, 2004 11:52 pm

http://www.abercon.co.uk/vtr1000/displa ... omment=VTR stutters after hard braking

Link to pic to solution to this problem
NB do the rear one too!!

Ben

PS if the links doesn't work, look in the gallery under misc

MDJ · Post by **MDJ** » Wed Jun 23, 2004 8:56 pm

Ah yes ! Nice one ben ..

SuperWheelie996 · Post by **SuperWheelie996** » Thu Jun 24, 2004 6:19 am

My superhawk, does the same thing after hard braking and a downshift to 1st gear, it sputters for a moment, then the idle goes back to normal, and it picks back up where it left off

VTR1000.ORG

hesitation after hard braking

hesitation after hard braking

yep