I recently purchased a new CBR1100XX and, getting straight to the point,
as is the case with just about every bike sold here in Australia today
it had a hesitation and surging problem anywhere between 60 and 100km per
hour when I'm just cruising along at a steady throttle.
Interestingly, Honda actually brag about the fuel mixtures they deliberately
set up on their new bikes, about 14.5:1 air fuel ratio, claiming smoother
power delivery and better fuel economy. This was all making sense to me
as it's one of the most common issues I deal with on a daily basis and
I'm sure it's due to the tough ADR compliance regulations manufacturers
have to overcome. So if you're riding around on a new or new secondhand
bike telling yourself "that must be just how it is", well I'm telling you
it's not just how it is, it's simply how it has to be to get through
ADR compliances.
The good news it can be corrected and here's how to do it, be warned
though, any modification which effects ADR compliances ie exhausts, rejetting,
remaping etc may result in a fine from those whom we all love and respect
if you ride on the road. The unit I use is our very own DFMS (Dynobike
fuel mangement system) see picture below. Available for many models they
are supplied with the appropriate wirng harness and plug in directly to
the injectors, which in my case I have 4. Once plugged in, find a suitable
spot under the seat to house the unit and following the instructions you
can then go through all the modes to fine tune it, though in most cases
you probably won't need to as most of the hard work has been done in our
dyno room to come up with best all round setting for your application.
In my case I have set it up for a stock standard bike with no modifications,
if I choose to change the exhaust or air filter down the track there's
still plenty of adjustment available in the unit without getting into trouble.
Below you can see the air fuel charts before and after showing how lean
it was in this area, on the road it's now very smooth and responsive and
much nicer to ride in the traffic.
Price for the unit $475.00, and there you go if you are suffering from
the same symptoms then there is an easy way to fix it without the need
for expensive tuning tools requiring hours of dyno time, wear and tear
on your bike.
It's now very easy to fit and inexspensive to buy, and you will
"feel the difference".
Fitting the DFMS unit (Dynobike Fuel Management System) as shown in
the pictures below we have enrichened the air fuel ratio to around 13:1
(see graph 1-blue line), which has transformed this bike into one that's
much more responsive, easier to control in traffic and much smoother to
ride at a steady throttle.
The big bonus: more power right through the rev range with a maxium
increase of about 8hp, see graph 2.
